|Publication number||US3475759 A|
|Publication date||Oct 28, 1969|
|Filing date||Oct 10, 1967|
|Priority date||Oct 10, 1967|
|Publication number||US 3475759 A, US 3475759A, US-A-3475759, US3475759 A, US3475759A|
|Inventors||John R Winegard|
|Original Assignee||Winegard Co|
|Export Citation||BiBTeX, EndNote, RefMan|
|Patent Citations (6), Referenced by (13), Classifications (22)|
|External Links: USPTO, USPTO Assignment, Espacenet|
Oct. 28, 1969 J. R. WINEGARD 3,475,759
TELEVISION ANTENNA WITH BUILT-IN CARTRIDGE PREAMPLIFIER Filed Oct. 10, 1967 4 Sheets-Sheet 1 Inventor John R. Winegarc] 35, @M 8: fl-bborneg-s Oct. 28, 1969 J. R. WlNEGARD 3,475,759
TELEVISION ANTENNA WITH BUILT-IN CARTRIDGE PREAMPLIFIER Filed Oct. 10, 1967 4 Sheets-Sheet 2 Inventor John R .Winegard fi'i'l'ornegs Oct. 28, 1969 J. R WINEGARD 3,475,759
TELEVISION ANTENNA WITH BUILT-IN CARTRIDGE PREAMPLIFIER Filed Oct. 10. 196? 4 Sheets-Sheet 3 I lhl Inventor John RJNinegard .55, (BM & fitter-1222.6
Oct. 28, 1969 J. R. WINEGARD TELEVISION ANTENNA WITH BUILT-IN CARTRIDGE FREAMPLIFIER 4 Sheets-Sheet 4 Filed Oct. 10, 1967 Km a r MR n w J m & Kweia :H'tornegs United States Patent Iowa Filed Oct. 10, 1967, Ser. No. 674,183 Int. Cl. H01q 1/26 US. Cl. 343-815 20 Claims ABSTRACT OF THE DISCLOSURE An improved television antenna capable of operating efficiently on all or any combination of television channels in the low and high VHF frequency bands, the FM broadcast band, and the UHF frequency band. The antenna includes a built-in cartridge preamplifier unit for amplifying received signals within selectable frequency bands and, for UHF operation, two or more vertical resonant reflector elements displaced vertically from the axis of the support boom for increased capture area, and certain mechanical innovations such as high strength, wrap-around support brackets and an ellipsoidally shaped support boom to prevent misalignment or sagging of the various dipole elements.
This invention relates to an improved television antenna for effective and efficient operation on any or all television and FM broadcast channels at any user location nothwithstanding differences in reception requirements that may be present. More particularly, it relates to an improved television antenna which includes a built-in, weatherproofed preamplifier asembly integral with the antenna structure capable of accommodating a series of printed circuit, solid-state cartridge amplifier or filter units of differing operating characteristics; a plurality of vertical resonant reflector elements for increased vertical capture area, and in turn higher gain, for the UHF operation; and to a number of operational design features to insure sustained optimum performance of the antenna as a whole and prevent sagging, loosening and misalignment of the respective dipole and parasitic elements.
With the advent of the UHF television channels (14 to 83) in the 470-890 megahertz frequency range in recent years, a real and substantial need exists for a television antenna capable of operating efficiently on any television channel (2 to 83) as well as the FM broadcast band. There are of course antenna structures known in the art which are capable of receiving signals in the combined VHF-UHF frequency bands. However, being capable of all-channel reception and operating efliciently on all television and FM channels are not one and the same thing. Until now, no prior art structure has been found which provides the desired level of operational characteristics, such as gain, impedance match, front-to-back ratio, di rectivity, etc., for each television and FM channel to be received nor being capable of meeting the specific operating requirements of differing reception locations.
It is of course well known that the gain of an antenna generally decreases with an increase in operating frequency. There are several reasons for this. First, the attenuation of the propagated signal of electro-magnetic energy increases as a function of frequency. That is, the signal power of a UHF channel, for example, is less at an antenna postioned at a given location than the signal power of a VHF channel notwithstanding both may have been transmitted from essentially the same location at the same power level. Another contributing factor inherently resides in the antenna structure itself. Although the driven elements providing UHF reception are cut to half-wave resonance in the same manner as those providing VHF signal reception, the physical length of the former is considerably less than that of the latter. This results in a decrease in the capture area provided by the UHF driven elements and consequently less gain.
Another problem frequently encountered in the past has been the widely varying ambient signal conditions encountered between various ultimate user locations. In some areas, VHF transmission stations are nearby but the UHF transmission stations are sufficiently far removed from such that the received signal strength falls below minimum acceptable limits. At other locations, the reverse may be true. Merely providing means for amplifying the received signals can not deemed an acceptable solution because the same disparity may be maintained. Moreover, there are still other ultimate user locations which may have adequate signal strength for the television and FM channels being received, but in which there is a substantial amount of signal energy outside the particular frequency bands and present an undesirable level of interference at the receiver. It is therefore obvious that a given antenna structure without more may provide acceptable operation at one user location while not at another.
In addition, there have been serious mechanical deficiencies in prior art antenna structures. Because of the relatively large physical dimensions of the associated elements of an antenna, high windloading, icing and the like commonly give rise to stresses, strains and distortions which ultimately result in sagging, loosening and misalignment of the various driven and parasitic elements. This not only results in an undesirable unsightly appearance but has a detrimental effect to the electrical performance characteristics. Exposure to the ambient atmosphere very often causes corrosion at the point of electrical connection between the driven dipole elements and the associated feeder lines.
It is therefore a general object of the present invention to provide an improved antenna structure capable of operating effectively and efliciently over all television and FM channels and in which the foregoing deficiencies have been eliminated or effectively minimized.
A more particular object of the present invention is to provide an antenna of the foregoing type in which a builtin, weather-proofed preamplifier assembly is incorporated as an integral part of the antenna structure for amplifying received signals within selectable frequency bands.
Still another object of the present invention is to provide an integrated preamplifier assembly of the foregoing type wherein separate, replaceable printed circuit, solidstate cartridge amplifier-filter units are accommodated to meet the operational requirements of the particular users location.
A further object of the present invention is to provide an integrated preamplifier assembly of the foregoing type wherein a cartridge unit may be incoporated comprising band-pass filter circuitry to pass signals within the television and FM channels and reject all signals outside the said channels with a high degree of attenuation.
Yet another object of the present invention is to provide a pair of parasitic reflectors cut for fullwave resonance at the lower end of the UHF frequency band and which reflectors are displaced vertically from one another and from the antenna support boom in a plane normal to the plane encompassing the boom and associated antenna dipole elements so as to increase the vertical capture area, and in turn the gain, with respect to UHF reception.
Another object of the present invention is to provide high-impact, Wrap-around insulator supports for mounting the respective dipole driven elements of the antenna, which insulator supports completely encapsulate the inner ends of the associated dipole driven elements at the connection point to the feeder line.
A still further object of the present invention is to provide insulator supports for the dipole driven elements of the foregoing type wherein the insulator halves are honeycombed with vertical partitions internally thereof for high resistance to stress and distortion so as to minimize sagging, loosening and misalignment of the dipole arms of the associated driven elements.
Another object of the present invention is to provide an antenna boom for supporting the respective driven and parasitic elements in a co-planar horizontal plane which antenna boom is formed in an ellipsoidal configuration to provide optimum rigidity and resistance to fiexure under wind-loading stress.
The novel features which are believed to be characteristic of the present invention are set forth with particularity in the appended claims. The invention, itself, however, together with further objects and advantages thereof, will best be understood by reference to the following description in conjunction with the drawings, in which:
FIGURE 1 is a view in perspective of a television antenna constructed in accordance with the present invention;
FIGURE 2 is a schematic diagram of the antenna of FIGURE 1;
FIGURE 3 is an enlarged fragmentary view in perspective of the antenna of FIGURE 1 showing the builtin, weather-proofed preamplifier assembly and vertical reflectors for the UHF section;
FIGURE 4 is an enlarged break-away view in perspective of the housing and cartridge unit of the preamplifier assembly shown in FIGURE 3;
FIGURE 5 is an enlarged fragmentary view in perspective of a wrap-around insulator support bracket for mounting the antenna dipole driven elements as shown in FIGURES 1 and 3;
FIGURE 5a is an enlarged view in perspective of the interlock bracket assembly for locking associated dipole arms in the desired position;
FIGURE 6 is an enlarged fragmentary view in perspective of the ellipsoidal-shaped configuration of the antenna support boom as shown in FIGURES 1 and 3;
FIGURE 7 is an enlarged fragmentary bottom-plan view showing a detail of the feeder lines for the VHF and UHF portions of the antenna structure and the base portion of the cartridge preamplifier housing;
FIGURE 7a is an enlarged fragmentary view in perspective of the cover portion of the cartridge preamplifier housing;
FIGURE 8 is an enlarged fragmentary cross-sectional view of the insulator support bracket taken generally along lines 8-8 in FIGURE 5;
FIGURE 9 is an electrical diagram of the circuitry of the cartridge unit shown in FIGURE 4 for amplifying received signals in both the UHF and VHF frequency band;
FIGURE 10 is an electrical diagram of the VHF bypass filter circuitry for substitution of the VHF amplification circuitry in FIGURE 9;
FIGURE 11 is an electrical diagram of the UHF bypass filter circuitry for substitution of the UHF amplification circuitry in FIGURE 9; and
FIGURE 12 is an electrical diagram of the band-pass filter circiut board for use in lieu of the cartridge amplifier circuit board as shown in FIGURE 4.
Referring now to the drawings, a television antenna is shown in FIGURE 1 which has been constructed in accordance with the present invention. The antenna 10 includes a very high frequency (VHF) section for reception of signals Within the 54 mHz. to 88 mHz. and the 174 mHz. to 216 mHz. frequency bands, indicated generally at 11, and an ultra high frequency (UHF) section for reception of signals Within the 470 mHz. to 890 mHz. frequency band, indicated generally at 12 (FIGURES 1 and 2). The antenna structure is supported on a vertical support mast M, to which a horizontal cross-arm or boom 4 B is affixed. The boom B is supported on the mast M by suitable means, such as the U-bolt clamp assembly (best seen in FIGURE 1).
The VHF section 11 of the antenna 10 includes a series of driven dipole elements 20, 22, 24 and 26 in the form of simple or linear dipoles in an aligned coplanar relationship to the axis of the boom B. It should be understood that a greater or lesser number of driven dipole elements may be provided without departing from the scope of the present invention. Each of the dipole elements 20 to 26 are supported on the boom B by a saddle support bracket formed of suitable insulating material, such as indicated at 30 in FIGURE 5. In one preferred form, bracket 30 is formed from a low-loss dielectric polystyrene material having high impact characteristics. Similar support brackets 32, 34 and 36 are used for mounting dipole driven elements 22, 24 and 26, respectively. It is to be understood that brackets 32, 34 and 36 are the same in all respects as the bracket 30 as shown in FIGURE 5.
Bracket 30 includes separate interlocking halves 30a and 30b. Each bracket half is symmetrical so as to wrap around the boom B both at the top and bottom (best shown in FIGURE 5). The bracket 30 is secured to the boom B by a suitable fastener, such as rivet 30r, passing thru clearance holes in the bracket 30 and boom B. Bracket 30, when affixed to the boom B, includes separate wing portions 30w extending laterally from the boom for mounting the separate dipole arms 20a and 20b of the driven element 20. The arms 20a and 20b are secured to the support bracket 30 by suitable fasteners, such as rivets 30r, passing thru clearance openings in the bracket 30 and arms 20a and 20b. It will be noted that the bracket wings 30w extend above and below each of the dipole arms 20a and 2012 at the point of afi'ixation (rivets 30r'). The arms 20a and 20b are sandwiched between the bracket halves 30a and 30b rather than merely being suspended from or supported on an associated bracket as was common practice in the past.
Moreover, the inner ends of the dipole arms 20a and 20b are encased within an associated interlocking bracket, such as indicated at 31 in FIGURE 5a. Interlock bracket 31 includes separate halves 31a and 31b, each having a flange portion 31d diverging slightly utwardly from the longitudinal axis of the bracket 31. 'lhe bracket 31 and dipole arm 20a and 20b pivot about the fastener 30r' passing thru clearance apertures 31r. Flanges 31d serve as interlocks by providing a force fit .vithin slotted indentations 30d (FIGURE 8) on the inside of bracket halves 30a and 30b to lock the dipole arms 20a and 20b in the extended position normal to the axis of the support boom B. The dipole arms 20a and 20b remain locked in this position by the action of the interlock brackets 31 until and unless flanges 31d are depressed sufliciently to permit them to swing clear of the slotted indentations 30d.
Bracket halves 30a and 30b further include a plurality of segmented upstanding vertical walls, indicated at 30x in FIGURE 8, internally thereof providing for a lightweight but extremely rigid and sturdy support bracket assembly when assembled about the support boom B. The assembled bracket provides a high resistance to flexure or other distortion so as to effectively eliminate subsequent sagging and/or misalignment of the associated dipole arms due to windloading, icing and the like.
Bracket 30 exhibits a further operational characteristic. That is, it completely encapsulates the electrical connection point between the inner ends of the associated dipole arms and the feeder lines FL. This connection point is made at the rivet fasteners 30r by wrapping the feeder line FL at least one turn around the same. Because the connection must be made metal-to-metal, the feeder lines FL cannot be coated at this location with any protective coating or other insulation. In the past, with the connection point exposed to the elements, corrosion frequently occurred with a resultant deterioration in the performance of the antenna structure. With the configuration of bracket 30, the electrical connection point between dipole driven elements and feeder line is effectively encapsulated so as to minimize such exposure and the attendant problems arising therefrom.
It will be noted from FIGURE 2, that the feeder lines FL are transposed between the VHF driven dipole elements -26. This line transposition is effected within the brackets 30, 32, 34 and 36 themselves. As shown in FIGURE 8, one feeder line FL passes thru the aperture g to the connection point around rivet 30r', transverse the bracket 30a along the channel 300 and out thru aperture 30n. The other feeder line FL passes thru aperture 30m to the connection point around the rivet 301", and transverse the bracket half 3% thru an associated channel (not shown) similar to channel 300 for bracket half 30a, and out thru aperture 30h.
Each of the other VHF driven elements 22, 24, and 26 also include a pair of dipole arms-22a-22b, 24a- 24b and 26a-26b, respectively. The VHF section 11 includes a unitary reflector element 28 to the rear of the rear dipole element 26 and a pair of parasitic elements and 42. Reflector 28 is mounted on a support saddle bracket 38 similar to brackets 30 and 36. Parasitic element 40 is mounted beneath the boom B a short distance in front of the driven element 20 and parasitic element 42 is mounted beneath the boom B and in direct vertical alignment with the driven element 22. The operation of the unitary parasitic elements 40 and 42 will be described subsequently.
An additional dipole director element 29 is positioned to the front of the VHF driven element 20. Director 29 includes a coupler element 290 connected between the inner ends of the dipole arms 29a and 29b. The dipole director element 29 is provided with a length such that, in combination with the coupler 29c, effective director action is provided for frequencies in the FM broadcast band (88 mhz. to 108 mhz.) and enhances the pickup of FM signals by the dipole driven element 20. On high VHF band operation (channels 7 thru 13), the coupler 29c is of a length that a resonance effect is obtained in combination with stray capacitance between the coupler and the metallic boom B, resulting in relatively high impedance between dipole arms 29a and 29b and permit them to act as separate unitary director elements in this frequency range. A more detailed description of the action effected by coupler of the type here identified as 29c may be found in US. Patent No. 2,700,105, granted to John R. Winegard.
Dipole director 29 also includes a serrated portion 29s at the outer ends of each of the dipole arms 29a and 29b which may be snapped off to reduce gain of the antenna on FM operation in those areas where strong FM signals are present and which would otherwise be a source of interference with the signals in the VHF frequency band. Sections 29s are easily removed by flexure thereof causing them to snap off at the serrations.
As shown, the UHF section 12 is positioned to the front of the VHF section 11 a predetermined distance and in a substantially coplanar relation thereto. The UHF section 12 consists of a series of dipole driven elements and associated parasitic elements. The driven elements are indicated at 50, 52 and 54 in FIGURES 2 and 3. The driven elements 50, 52 and 54 are interconnected at their inboard ends by a pair of open-wire feeder lines F'L', but which are not transposed between adjacent dipole driven elements. A dipole director element 56 is positioned to the front of driven element 50 and a pair of unitary director elements 57 and 58 are positioned to the front of dipole director 57, in the manner indicated. In addition, a pair of dipole reflector elements 60 and 64 are also provided which are displaced vertically (FIGURES l and 3) from the UHF driven elements in a plane normal to the horizontal plane of the antenna structure.
The inner ends of the UHF dipole reflector element 60 are affixed to a saddle bracket 61 which is in turn carried on a support mast 63 extending upwardly and slightly backwardly with respect to the front of the antenna structure 10 (best seen in FIGURE 3). Similarly, the inner ends of the UHF dipole director element 64 are affixed to a saddle bracket 65 mounted to a support mast 66 extending downwardly and slightly backwardly. Support masts 63 and 66 are affixed to the main boom B by suitable fasteners, such as a wing nut and bolt assembly 67, passing thru clearance holes in the masts 63, 66 and boom B.
Driven elements 50, 52 and 54 are cut to physical lengths for resonating at particular frequencies across the UHF frequency band. Unitary director elements 57 and 58 and dipole director element 56 are cut to lengths to provide effective director action. Dipole reflector elements 60 and 64 are cut to lengths for resonating at frequencies slightly below the lower end of the UHF band for effective reflector action. The advantages and significance of the vertical displacement of the reflector elements 60* and 64 will be described subsequently. It is also to be understood that a greater or lesser number of dipole driven elements and associated parasitics may be provided for the UHF section 12 without departing from the scope of the present invention. In particular, additional resonant dipole reflector elements may be provided to enhance the performance of the antenna on UHF operation. In another embodiment of the invention, an additional resonant dipole reflector was included, mounted on the main boom B at a position in vertical alignment with the displaced vertical dipole reflectors 60 and 64, such as shown at 69 in FIGURE 3.
As more clearly shown in FIGURES l, 3 and 4-, the antenna 10 includes a built-in cartridge preamplifier assembly 70 integral with the antenna structure. The cartridge amplifier 70 includes a weather-proof housing 71 consisting of a base portion 72 and a cover portion 74. The cartridge housing is preferably formed of a highimpact, weather-resistant insulating material, such as polystyrene. The base portion 72 is mounted directly to the underside of the main boom B by a fastener, such as rivet 72r (FIGURE 7) passing thru clearance holes in the base 72 and boom B. The respective feeder lines FL and FL pass thrus clearance holes in the front and back vertical walls of the base 72 and terminate in aligned, open-ended condition therewith as shown in FIGURE 7. The terminal ends of the feeder lines FL and FL are supported on slotted vertical support posts indicated at 72p. The cover portion 74 is aflixed to the base portion 72 by fasteners, such as machine screws (not shown), passing thru clearance holes 74m in the cover 74 and mat ing with threaded openings 72m in the base portion 72. The cover portion 74 also includes a pair of channels 74c extending vertically along opposing sides in the interior of the cover 74 (as shown in FIGURE 7a) and also an opening 74b in the bottom end (as seen in FIGURE 4).
In the assembled condition, the cartridge preamplifier assembly 70 accommodates an associated cartridge amplifier or filter unit 76. The cartridge unit 76 is formed by a printed circuit chassis board 78 on which the associated amplification or filtering circuitry components are mounted. The cartridge circuit board 78 includes a series of terminal prongs 80 affixed thereto extending upwardly from the top edge (FIGURE 4) and which are aligned to engage a respective one of the feeder lines FL and FL. The terminal prongs 80 serve as the input connection points to the amplification or filtering circuitry. A connector 82 is included at the bottom end of the cartridge circuit board 78 for connection to the down line DL. Connector 82 serves as the output from the cartridge preamplifier assembly 70 and may be of the coaxial jack type identified at 82a (FIGURES l0 and 11) to accommodate the nominal 72 ohm coaxial cable or a pair of screw terminals identified at 82b (FIGURE 9) to accommodate the conventional twin-lead having a nominal characteristic impedance of approximately 300 ohms.
In assembling the preamplifier unit, the associated down line DL is inserted thru the opening 74b in the bottom of the cover portion 74 of the housing 71 and affixed to the connector 82 on the circuit board 78. Circuit board 78 is inserted in the cover portion 74 within the vertical channels 740. Upon affixing the cover portion 74 to the base portion 72, the terminal prongs 80 engage the appropriate feeder line FL and FL.
It should be noted that the cartridge preamplifier assembly 70 is intended to accommodate a wide variety of cartridge amplifier units 76 having differing amplification or filtering performance characteristics. The reception requirements differ widely between user locations. In some instances, the user is at a location which is relatively close to stations transmitting signals on the VHF channels but at the same time far removed from stations transmitting signals on the UHF channels. The result is that the received signals in the UHF frequency band are below the minimum signal level for proper operation of the television receiver. The reverse may be encountered at other user locations. At some user locations, the received signal strength may be adequate for both UHF and VHF channels without amplification. At still other locations, there may be extraneous electromagnetic energy present which is outside the particular received television channels which causes interference in the receiver. In addition, some users may prefer to employ nominal 75 ohm shielded coaxial cable while others may prefer the conventional twin-lead transmission line having a characteristic impedance of approximately 300 ohms. Some means of properly matching the various impedances is therefore desirable.
It will be seen, then, that there are a number of reception requirements which differ from one user location to the other. The present invention overcomes the attendant difficulties presented by providing a cartridge amplifier or filter unit which specifically meets the reception requirements of the particular location. It has been found that approximately seven different cartridge amplifier or filter units are adequate to meet the needs of substantially every reception requirement, although it is to be understood that the present invention is not to be limited to any specific number. Specifically, one cartridge amplifier unit 76 is provided which amplifies received signals in both the UHF and VHF frequency bands and has an output of approximately 300 ohms. Another cartridge unit provides the same amplification characteristics but has an output of approximately 75 ohms. Another cartridge unit includes circuitry for amplifying received signals in the VHF band but incorporates a filter network for bypassing signals in the UHF band directly FIGURE 9 is representative schematically of the circuitry identified generally at 100 for amplifying received signals in both the UHF and VHF frequency bands with an output of approximately 300 ohms for use with a down line of the twin-lead type. As shown, a balun transformer 101 is interposed between terminal prongs 80 in contact with the feeder lines FL for the VHF section 11 and the input to a transistor amplifier stage 102. Balun transformer 101 effects a 4:1 step-down in the nominal 300 ohm impedance of the antenna 10. Transistor stage 102 includes a transistor 103 for effecting amplification of signals within the VHF frequency range. The output of transistor 102 is coupled to a reference point 104 and, in turn coupled to the output connector 82b through balun transformer 105 effecting an appropriate 4:1 stepup in impedance to the desired 300 ohms. The various component parts connected to the base, emitter and collector electrodes of transistor 102 provide the correct bias, operating power and bandpass filtering reqiurements in the manner known in the art such that specific and detailed description is deemed unnecessary. The filter circuitry indicated within the dotted line 106 provides a bandpass response of approximately mHz. to 88 mHz. and 170 mHz. to 220 mHz. Filter circuitry 106 also includes a filter trap circuit 107 consisting of inductances 107a107d and capacitors 107b-107c for bypassing fre quencies in the range 90 mHz. to 168 mHz., covering the FM and aviation bands, directly to ground.
In like manner, a balun transformer 111 is interposed between the terminal prongs 80 in electrical contact with the UHF feeder lines FL and the input to a transistor amplifier stage 112 for amplifying received signals in the UHF frequency band. Amplifier stage 112 includes the transistor 113 whose output is coupled to the reference point 104, and in turn to the output connector 82b thru balun transformer 105. Again, the various components connected to the base, emitter and collector electrodes provide the necessary bias, operating power and bandpass filtering requirements in the conventional manner. The bandpass characteristics for the transistor amplifier stage are approximately 470 mHz. to 890 mHz. Operating power for transistors 103 and 113 is supplied by a separate power supply unit (not shown) through down line DL. This is permissable since the voltage level required is relatively low. In the preferred form, an alternating current voltage is applied thru the down line DL, one side 105a of the balun transformer 105 to the rectifier SR. Rectifier SR effects the application of a unidirectional voltage on the order of 12 volts between the collector and emitter electrodes of transistors 103 and 113 in the manner shown.
In one specific embodiment of the circuitry illustrated schematically in FIGURE 9, the following operational to the output of the cartridge unit without amplification. performance a a i s w re o tained:
VHF UHF Gain 12 db ave 6 db ave. VSWR 121.4 ave 1:1.4 ave. Max. signal output 480,000 mlc o-vo ts 220,000 micro-volts. Bandpass 50 mHz. to 88 111132; 170 mHz. to 220 mHz 470 mHz. to 890 mHz. Band rejection 00 mHz. to 168 mHZ Response 1% d per 6 Z- c flnnel 1% db per 6 mHz. channel This cartridge unit exhibits an output of approximately 300 ohms. Another cartridge unit has the same VHF amplification and UHF by pass characteristics but an output of ohms. Still another cartridge unit includes amplification circuitry for amplifying received signals in the UHF band but incorporates filter circuitry to by pass signals in the VHF range directly to a 300 ohm output terminal. A corresponding cartridge unit with UHF amplification circuitry and VHF bypass filter circuitry is provided with a 75 ohm nominal output. Still another cartridge unit incorporates high and low pass filter networks for passing signals in the respective VHF and UHF frequency bands and rejecting signals at all other fre quencies.
For a cartridge amplifier unit to provide amplification for received signals in the UHF band but effect a by pass of the received signals in the VHF band, a by pass filter circuit 120 as shown within the dotted lines 121 in FIG- URE 10 may be substituted for the circuitry between the reference points X and Y of FIGURE 9. By pass filter 120 includes a filter trap 122 similar to that identified at 107 in FIGURE 9 to trap out received signals within the frequency range of mHz. to 168 mHz. Circuitry also includes a low pass filter network 123 which provides a low impedance for signals below a reference frequency of approximately 220 mHz. In addition, FIG- URE 10 shows the use of a coaxial jack 82a connected directly to reference point 102 to effect an output of approximately 75 ohms instead of the balun transformer 105 providing a nominal 200 ohms.
For a cartridge amplifier unit providing amplification for received signals in the VHF band but by passing signals in the UHF band, a by pass filter network 130, as shown within the dotted lines 131 in FIGURE 11, is substltuted for the amplification circuitry between the reference points Y and Z in FIGURE 9. Filter network 130 comprises a high pass filter circuit such that signals recelved at the input terminals 80 in contact with the UHF feeder lines FL above the 470 mHz. range encounter a low impedance path and thus by passed directly to the output terminal 82a.
In those instances where amplification is not required for the received signals, but where extraneous signal energy may be present outside the television frequency bands thereby causing interference, the filter circuitry identified at 140 may be incorporated. The filter 140 includes a low pass filter network indicated by the dotted lines 141 and a highpass filter network indicated by the dotted lines 142. Signals within the VHF frequency band readily pass from the VHF section 11 of the antenna to the terminals 82b at which the down line DL is connected, but offers a relatively high impedance to any signals above the VHF band. Likewise, signals within the UHF frequency band readily pass to the connection points 82a at the down line DL but offer a high impedance to any signals below the UHF band.
From FIGURES 4 and 5, it will be noted that the physical configuration of the main support boom B is not the conventional circular shape, but rather of a generally ellipsoidal one. It has been found that the ellipsoidal configuration of the boom provides a substantially greater resistance to flexure and twisting of the boom as well as higher support strength than is evidenced in previous boom configurations. Such configuration also insures that the various support brackets 30, 32, 34, 36 and 38 will not skew out of alignment because they are not held merely by a single rivet as in previous structures, but by the entire (non-circular) circumference of the boom in contact with the interior of the bracket central opening.
The antenna 10 is preferably formed of aluminum tubing or rod. The phasing lines and the various driven dipoles and parasitic elements can be stamped or cast from metal plate in one or more sections, if desired. In one specific construction found satisfactory, the arms of the driven and parasitic elements were formed from 0.375 inch O.D. aluminum tubing with the boom B formed of seamless aluminum stock approximately A; inch by 1% inches. The tubing may be anodized or left uncoated as desired.
The foregoing description gives the general organization of the antenna 10. Its more specific construction will be better understood by reference to the following dimensions which were used for an antenna found highly effective for operation on any channel in the television frequency spectrum:
VHF SECTION Arm Span, length,
Element inches, inches Unitary Reflector 28 112 Driven Dipole 26. 104 50% Driven Dipole 24.. 8s 42% Driven Dipole 22. 76 36 A Driven Dipole 20 52 24 2 Unitary Element 4 26 Unitary Element 40 26 Dipole Director 291 52 24% UHF SECTION Dipole Reflector 64 23 10% Dipole Reflector 60 23 10% Driven Dipole 54.. 17 7% Driven Dipole 52. 15 6% Driven Dipole 50. 14 6 Dipole Director 56! 10% 4 Unitary Director 57. Unitary Director 58 5% The coupling unit 29c has a total length of approximately 17 inches. The vertical distance between the dipole reflector elements 60 and 64 is approximately 21 /2 inches.
Distances along the boom B between the respective elements of the antenna 10 are as follows:
Distance between elements 28 and 26 8%" Distance between elements 26 and 24 7 Distance between elements 24 and 22 7" Distance between elements 22 and 20 8" Distance between elements 20 and 29 9" Distance between elements 29 and 54 5" Distance between elements 54 and 52 3 /2" Distance between elements 52 and 50 3" Distance between elements 50 and 56 2 /2" Distance between elements 56 and 57 4%" Distance between elements 57 and 58 4%" PRACTICAL OPERATION In the practical operation of antenna 10 on low VHF band operation (channels 2 to 6), the dipole elements 20 thru 26 are cut to resonate at frequencies spread over the band. For example, for channel 2 operation, dipole element 26 may be cut to approximately halfwave length for effective reception of signals on that frequency. The remaining VHF driven elements either provide limited director action or are substantially ineffective. Reflector action is provided by the reflector 28 cut to resonate somewhat below the lower end of the low VHF band. At the other end of the VHF band, channel 6, one of the front positioned dipole elements, say dipole 22, is cut to a length providing halfwave resonance for efficient reception of signals at that frequency. It is to be understood, however, that the respective VHF dipole driven elements do not individually become active or inactive at any particular frequency. Rather, more than one driven element contributes gain at most if not all frequencies.
Another factor to be considered in the operation of the antenna on the low VHF band is the relatively close physical spacings between the dipole driven elements 20 thru 26 in combination with the feeder lines FL between dipole elements 22 and 24 and between elements 24 and 26. The feeder line FL between these dipole elements includes a series of sinuosities or reversing bends S in the elements which make the lengths of the lines substantially longer than the spacings therebetween (see FIGURE 5). The physical spacing between elements 22 and 24 and between elements 24 and 26 are seen to be approximately seven inches but the interconnecting feeder lines are of lengths on the order of 15 inches or greater. It is to be understood, however, that the exact spacing between the dipole driven elements and the lengths of the interconnecting feeder lines is not critical and may be varied over a predetermined latitude without substantially altering the performance characteristics of the antenna 10 on low VHF band operation.
It has been found that in an antenna array of three or more dipole driven elements cut for resonant action in the low VHF 'band that, for the most effective operation of the antenna as a whole, only the front two of such low VHF band dipole elements should provide any substantial output in the high VHF band. Thus, it is possible to provide relatively close spacings between driven dipole elements other than the first two as long as the associated interconnecting feeder lines are substantially longer than the spacings therebetween. This arrangement provides enhanced operation on low VHF band. However, the feeder lines are unduly long for eifective operation on the high VHF band. As more fully described in a co-pending application, Ser. No. 494,324, and assigned to the same assignee as the present invention, the approximately seven inch spacing between dipole elements 22 and 24 and between elements 24 and 26 and the corresponding 15 inch or greater length of interconnecting feeder lines FL give rise to around a 60 degree phase displacement between the voltage of the first two dipole elements as seen at the terminals of the first dipole driven element. Moreover, the feeder lines FL between dipole elements 22 and 24 and between elements 24 and 26 serve as impedance correlators, that is, they are effective to step-up the impedance of the nominal 75 ohms linear dipole to that approximating 300 ohms for optimum match to the conventional twin-lead line and the television receiver.
On high VHF band, the dipole 20 serves as the main signal pickup element. With a physical length of approximately 52 inches, a halfwave resonance of approximately 225 mHz. is seen to be obtained to improve overall directivity and impedance match characteristics of the antenna on low VHF band operation. The same dipole physically is slightly more than three-quarter wave resonant at the center of the high VHF band, for example, around 195 mHz. Taking into account capacitance end effects that are present, however, dipole element will be seen to approach fullwave resonance at this high VHF band reference frequency.
Parasitic element 40 is placed in close proximity to the dipole element 20 so as to reduce the otherwise relatively high impedance resulting from fullwave resonance in the high VHF band to a value approaching the 300 ohm level. function of the other parasitic element 42 is to substantially reduce the impedance of dipole driven element 22 at the connection points to the feeder line FL so that a corresponding high impedance may be reflected back across the antenna feed point at the inboard ends of dipole element 20 and thus effect a decoupling action with respect to all of the antenna structure to the rear of dipole element 20 on high VHF band operation. This decoupling action takes place due to the feeder lines FL between dipole elements 20 and 22 being on the order of a quarterwave length with respect to the high end of the high VHF band, thereby acting in the manner of a quarterwave stub. To this end, parasitic element 42 may be mounted directly beneath or directly over the associated dipole element 22 on the support bracket 32, but in either case, in direct vertical alignment with dipole 22. The vertical spacing therebetwcen is on the order of one to one-and-a-half inches. Both of the parasitic elements 40 and 42 are seen to be cut to physical lengths providing halfwave resonance at the high end of the high VHF band, that is, at about 200 mHz. or higher. This decoupling action for dipole driven elements by use of associated parasitic elements is more fully described in US. Patent 3,321,744, granted to John R. Winegard et al.
For UHF operation, the active elements are the dipole driven elements 50, 52 and 54, cut to particular frequencies within this range. These driven elements are interconnected by a straight open-wire feeder line FL. Director action is provided by the unitary directors 57 and 58 and the dipole director 56. Although additional driven elements may be provided, it has been found that with at least three driven elements, a reasonably good impedance match is achieved with respect to a 300 ohm feeder line, such as that indicated at FL.
Without more, however, the gain of the UHF section 12 may not be adequate for all user locations and will, in any event, be less than that provided by the VHF section 11. This is because the physical lengths of the halfwave resonant elements are substantially less than the physical lengths of the halfwave resonant driven elements on low VHF operation and the fullwave resonant driven element on high VHF band operation. The shorter lengths of the UHF elements result in less capture area and consequently less gain.
The resultant gain on UHF operation, however, is substantially increased thru the action of the vertical dipole reflectors 60 and 64. As previously described, the dipole directors 60 and 64 are displaced vertically from the axis and horizontal plane of the boom B. Each of the dipole directors 60 and 64 is cut to a physical length to provide substantially fullwave resonance slightly below the low 12 end of the UHF band, 470 mHz. In this sense, they may be termed resonant reflectors as distinguished from parasitic reflector elements of substantially longer (or shorter) lengths and thus exhibiting resonance at frequencies substantially different than the reference frequency at the low end of the UHF band.
The vertical resonant reflectors and 64 provide a substantial increase in the vertical capture area for the antenna 10 on UHF operation, thereby providing an increase in antenna gain. It has been found that the incorporation of vertical resonant reflectors, such as elements 60 and 64, provides substantially more gain on UHF operation than the conventional single halfwave reflector element in coplanar relation to the UHF driven elements, or the gain provided by separate corner reflectors, 4-bay bow ties and other configurations.
While only one specific embodiment of the present invention has been shown and described herein, it will, of course, be understood that other variations and modifications may be etfected without departing from the true scope and spirit of the present invention. The particular construction of the support brackets, cartridge housing and amplifier units, the connections between the various driven elements, the transmission lines, the specific dimensions and number of the dipole and unitary elements, and other factors may be varied to suit the convenience of the maker or user of the antenna. The appended clims are intended to cover all such modifications and alternative constructions that fall within their true scope and spirit.
What is claimed is:
1. A television antenna effective for the reception of signals in both the low and high VHF frequency bands, comprising in combination:
a horizontal support boom;
a plurality of dipole driven elements arranged in a coplanar array and supported on said boom in a substantially parallel aligned relation to each other, said driven elements having differing lengths to provide effective operation and coverage of the low VHF band, the first said dipole driven element positioned front most in the array further being of a length to provide substantially fullwave resonance at a frequency within the high VHF band and serve as the primary pickup element therefor;
interlocking support means for positioning and maintaining said dipole driven elements in said substantially parallel aligned relation to each other;
a transmission line interconnecting said driven dipole elements at their inboard ends to provide signal effects due to their combined action, said transmission line between adjacent driven dipole elements other than the first two such elements in the array being of a physical length which is at least twice that of the physical spacings between said adjacent dipole elements;
a first unitary parasitic element deposed a short distance in front of said first dipole driven element acting as the primary pickup element in the high VHF band and coupled thereto so as to provide an effective impedance match between said first dipole driven element and the transmission line on high VHF band operation;
at least one other unitary parasitic element deposed in vertical alignment with one of the other dipole driven elements and closely coupled thereto; and
a cartridge amplifier unit integral with the antenna array for selectively amplifying signals in the VHF bands having an output and an input coupled to the transmission line interconnecting the dipole driven elements.
2. A television antenna effective for the reception of 13 signals in both the VHF and UHF comprising in combination:
a horizontal support boom;
a VHF section including, a plurality of dipole driven elements arranged in a coplanar array and supported on said boom in a substantially' parallel aligned rela tion to each other, said driven element having differing lengths to provide effective Operation and coverage of the low VHF band, the first said driven dipole driven element positioned front most in the array further being of a length to provide substantially fullwave resonance at a-frequency within the high VHF band and serve as the primary pickup element therefor,
interlocking support means for positioning and maintaining said VHF dipole driveri elements in said substantially parallel aligned relation to each other,
first transmission line interconnecting said VHF driven dipole elements at their inboard ends to profrequency bands,
vide signal effects due to their gombined action, said transmission line between adjacent VHF driven dipole elements other than the first two such elements in the array being of a physical length which is at least twice that of the physical spacings between said adjacent dipole elements, 1 Y first unitary parasitic element deposed a short distance in front of said first VHF dipole driven element acting as the primary pickup element in the high VHF band and coupled thereto so as to provide an effective impedance match between said first VHF dipole driven element and thetransmission line on high VHF band operation, and at least one other unitary parasitic element deposed in vertical alignement with one ofthe other VHF dipole driven elements and closely-coupled thereto; UHF section including, a plurality of dipole driven elements arranged in a coplanar array and supported in a substantially parallel aligned relation to each other on said boom at a position in front of said VHF driven dipole elements, said UHF driven dipole elements having differing lengths to provide coverage of the UHF band, second transmission line interconnecting said UHF dipole driven elements to provide signal effects due to their combined action, and at least two parasitic reflector elements having lengths to provide effective reflector action in the UHF band, said UHF reflector elements .being displaced vertically from each other above and below the plane of the antenna array as defined by said dipole driven elements; and a cartridge amplifier unit integral with the antenna array for selectively amplifying signals in the UHF and VHF bands, said cartridge amplifier having an output and a first input coupled to said first transmission line interconnecting said VHF dipole driven elements and a second input coupled to said second transmission line interconnecting said UHF dipole driven elements. I 3. A television antenna in accordance with claim 1 wherein the interlocking support means for positioning and maintaining each of the VHF dipole driven elements in parallel aligned relation to each other includes a support bracket assembly, said support bracket assembly having symmetrical halves assembled about the antenna boom with wing portions extending laterally on each side of the antenna boom, which wing portions encompass a suflicient portion of the inboard ends ,of the dipole arms of an associated VHF dipole element so as to effectively encapsulate the electrical connection point between said associated dipole arms and the interconnecting transmission line, and interlock means to lock said associated dipole arms in their intended operational position normal to the longitudinal axis of the antenna boom.
4. A television antenna in accordance with claim 3 wherein the interlock means includes a slotted guide channel formed in the interior of each of said bracket wing portions and an interlock sleeve encompassing the inboard ends of each of said associated dipole arms, said interlock sleeve having a flared out flange portion extending slightly beyond the extremities of the support bracket assembly, said flared out flange portion being positioned for snapping into said slotted guide channel by spring action when the associated dipole arms are moved to their operational position normal to the antenna boom,
5. A television antenna in accordance with claim 3 wherein each 'of the support bracket assembly halves includes a plurality of upstanding vertical walls the interior thereof for effecting increased rigidity and load bearing capabilities of said support bracket when assembled about the antenna boom.
6. A television antenna in accordance with claim 1 wherein the antenna boom is formed in an ellipsoidal shaped configuration with respect to the longitudinal axis thereof.
7. A television antenna in accordance with .claim 1 wherein the spacing between the first and second VHF dipole driven element is approximately eight inches and the spacing between each of the other adjacent VHF dipole driven elements is approximately seven inches and the physical length of the transmission line interconnecting said adjacent VHF dipole driven elements other than said first two is at least 15 inches.
8. A television antenna in accordance with claim 1 wherein the first unitary parasitic element is mounted beneath the antenna boom at a position between one and four inches in front of said first VHF dipole driven element and wherein each of said parasitic unitary elements is of a length to provide halfwave resonance at a frequency at or above the upper end of the high VHF frequency band.
9. A television antenna in accordance with claim 1 wherein said other unitary parasitic element is spaced at a distance from its said associated VHF dipole driven element to provide a decoupling action thereto on high VHF band operation by causing a high impedance to be reflected down the transmission line and across the inboard ends of said first VHF dipole driven element.
10. A television antenna in accordance with claim 2 wherein each of two vertically displaced parasitic reflector elements is of a length to provide fullwave resonance at a frequency slightly below the lower end of the UHF frequency band.
11. A television antenna in accordance with claim 2 wherein each of the vertical resonant reflector elements for the UHF band are affixed to an associated support mast extending respectively outwardly and rearwardly, above and below, the antenna boom.
12. A television antenna in accordance with claim 2 wherein the vertical displaced reflector elements are supported on associated support masts extending outwardly and to the rear, above and below, the antenna boom and wherein each of said support masts are releasably collapsible to a position parallel to said antenna boom to facilitate packing and shipping of the antenna array.
13-. A television antenna in accordance with claim 2 wherein three parasitic resonant reflector elements are incorporated, each of said reflector elements being of a length for providing fullwave resonance at a frequency slightly below the lower end of the UHF band, one of said reflector elements being mounted on an associated support mast extending upwardly and slightly to the rear with respect to the antenna boom, another reflector element being mounted on an associated support mast extending downwardly and slightly to the rear with respect to the antenna boom, and the third reflector element being mounted directly on the antenna boom, all three of said reflector elements being in substantially vertical alignment with respect to one another.
14. A printed circuit cartridge preamplifier assembly integral with an all-channel television antenna, which antenna includes active and passive elements forming respective VHF and UHF sections supported on a common boom and pairs of open wire transmission feeder lines selectively interconnecting the active elements in each of the VHF and UHF sections, and which preamplifier assembly selectively amplifies signals in the VHF and UHF frequency bands, said preamplifier assembly comprising in combination:
a Weatherproof cartridge housing formed of insulating material having an upper base portion affixed to the underside of the antenna boom and a lower removable cover portion, said base portion having apertures through which the pairs of open wire transmission feeder lines may pass therethrough approximately parallel to the antenna boom; and
a detachable cartridge preamplifier unit insertable within said cartridge housing, said cartridge amplifier including a printed circuit chassis board for mounting associated amplification circuitry, which circuitry forms separate signal paths for selectively amplifying signals in each of the VHF and UHF frequency bands, respectively, said cartridge amplifier having an input for each of said VHF and UHF signal paths and a common output, said chassis board including terminal prongs at said respective inputs which engage said pairs of open wire transmission lines upon insertion of the chassis board within said cartridge housing.
15. A cartridge preamplifier unit in accordance with claim 14 wherein the cartridge chassis board includes amplification circuitry for amplifying television signals in the VHF frequency band and additional and separate amplification circuitry for amplifying television signals in the UHF frequency band.
16. A cartridge preamplifier unit in accordance with claim 14 wherein the cartridge chassis board includes amplification circuitry for amplifying television signals in the VHF frequency band and addtional and separate high-pass filter circuitry for by-passing to said output television signals in the UHF frequency hand, without amplification.
17. A cartridge preamplifier unit in accordance with claim 14 wherein the cartridge chassis board includes amplification circuitry for amplifying television signals in the UHF frequency band and addtional and separate low-pass filter circuitry for by-passing to said output television signals in the VHF frequency band, without amplification.
18. A cartridge preamplifier unit in accordance with claim 14 wherein the chassis board includes a balun transformer between the input terminals engaging the open wire transmission feeder lines and the amplification circuitry for effecting a 4:1 impedance transformation between the nominal 300 ohm characteristic impedance of said feeder lines and an output terminal jack for connection to a coaxial transmission down line having a nominal characteristic impedance of ohms.
19. A television antenna effective for reception of signals in the UHF frequency band, comprising in combination:
a horizontal support boom;
a plurality of dipole driven elements arranged in a coplanar array and supported on said boom in a substantially parallel aligned relation to each other, said dipole driven elements having differing lengths to provide effective coverage of the UHF band;
a transmission-line interconnecting said dipole driven elements to provide signal effects due to their combined action;
at least two parasitic reflector elements having lengths to provide fullwave resonance at a frequency slight- 1y below the lower end of the UHF band, said reflector elements being displaced vertically with respect to each other above and below the plane of the antenna array as defined by said dipole driven elements; and
a cartridge amplifier unit integral with the antenna array for amplifying signals in the UHF band, said cartridge amplifier unit having an output and and input coupled to said transmission line interconnecting said dipole driven elements.
20. A television antenna in accordance with claim 19 wherein a plurality of director elements are also incorporated, which elements are of the parasitic type and positioned to the front of said dipole driven elements and supported on said antenna boom.
UNITED STATES PATENTS 2,578,973 12/1951 Hills 343-701 XR 2,757,244 7/1956 Tomcik 333-6 XR 3,066,266 11/1962 Fisher 333-25 3,086,206 4/1963 Greenberg 343-815 3,163,864 12/1964 Grecnberg 343-812 XR 3,195,076 7/ 1965 Morrison 333-26 OTHER REFERENCES Channel Master Crossfire Series 3600 Channel Master Corp, Ellenville, NY. 1961, 10 pages.
HERMAN KARL SAALBACH, Primary Examiner MARVIN NUSSBAUM, Assistant Examiner US. Cl. X.R.
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|U.S. Classification||343/815, 455/291, 343/819, 343/816, 455/273, 343/882, 343/701|
|International Classification||H01Q5/00, H03F3/191, H01Q1/26, H01Q19/30, H01Q1/12|
|Cooperative Classification||H01Q5/0089, H01Q1/26, H01Q1/1228, H03F3/191, H01Q19/30|
|European Classification||H01Q5/00M6A, H03F3/191, H01Q19/30, H01Q1/26, H01Q1/12B3|