US 3501767 A
Description (OCR text may contain errors)
March 17, 1.970 JQ VELEZ 3,501,767
ULTRA-HIGH FREQUENCY TALE TOP DIPOLE MAT ANTENNA Filed Nev. 1s, 196e Il INCHES (APPROX.)
INVENTOR. JOSEPH VELEZ BYM/l,
ATTORNEY United States Patent O 3,501,767 ULTRA-HIGH FREQUENCY TABLE TOP DIPOL'E MAT ANTENNA Joseph Velez, Jackson Heights, N.Y., assigner to Lambda Antenna Systems Corp., Astoria, N.Y. Filed Nov. 18, 1968, Ser. No. 776,324 Int. Cl. H01q 9/28 U.S. Cl. 343-795 4 Claims ABSTRACT OF THE DISCLOSURE The perpendicular span between each of the apices andv its respective base is 8 inches. A two wire, 300 ohm transmission line is connected to the apices.
BACKGROUND OF THE INVENTION This invention relates to antennas and more particularly an antenna for receiving television `signals on the upper transmission band known as U.H.F. (ultrahigh frequency).
In recent years the use of this band has been rapidly increasing for economic and technical reasons, due to the availability of a large number of ultra-high frequency channels as compared with the heretofore used very high frequency channels. Reception of the ultrahigh frequency band signals is often poor because insuicient signal energy reaches the antennas for satisfactory operation of television receivers. The present invention constitutes a substantial improvement in antenna performance over known portable antennas used heretofore for ultra-high frequency reception.
It is accordingly an object of the invention to provide a small light-weight antenna structure which will provide the most efficient transfer of energy to a television receiver while accommodating uniform response throughout the ultra-high frequency band.
Another object of the invention is to provide an antenna for indoor reception of television s-ignals on the ultra-high frequency band having dimensions approaching the optimum values for good signal reception.
A further object of the invention is to provide a receiving antenna of the character described which can be laid on a horizontal plane surface and at the same time be inconspicuous.
Yet another object of the invention is to provide an antenna of the above mentioned character which can serve simultaneously as a mat for decorative objects placed thereon, without affecting its optimum values for signal reception.
Still another object of the invention is to provide an antenna of the above-described character which is extremely simple and inexpensive to fabricate, easy to install and which requires no maintenance.
Other objects, features and advantages of the invention will be apparent from the following detailed specification when read with the accompanying drawing.
It is to be understood, however, that the invention is not limited to the precise details disclosed, but that changes in detail, construction materials and parts may be made within the scope of the appended claims.
In the drawing:
FIG. 1 illustrates the antenna as used with a television receiver;
3,501,767 Patented Mar. 17, 1970 FIG. 2 is a top plan view of the antenna elements proper, according to the invention;
FIG. 3 is a top plan view of the antenna enclosed in suitable cover; and
FIG. 4 is a cross-section taken on line 4 4 of FIG. 3.
Referring now to the drawing in detail, the complete antenna I6 is placed substantially horizontally on the top 8 of a television receiver. A vase 12 illustrates the use of the antenna 6 as a decorative mat.
The antenna elements 14 and 14 comprise a pair of triangular laminae arranged with their apices 16, 16 opposite one another. Each apex constitutes a 70 angle, while the bases 18, 18' of the triangle laminae measure 11 inches each, the perpendicular span between the bases 18, 18 and apices 16, 16 being 8 inches in each case.
The laminae are preferably made of aluminum, due to its low cost. They can be made, however, of copper, zinc or other good conductors, if desired.
Secured to the apices 16, 16 by known means, at 20, 20 is a two-wire 300 ohm transmission line lead 22, the free ends 24, 24 of which are provided with lugs 26, 26 for connecting the lead 22 to the television receivers antenna posts.
As shown in FIGS. 3 and 4, iboth laminae arranged in the above described manner are encased in an envelopelike cover consisting of a pair of non-conductive sheets of material 28, 2'8 which are sewn to one another about their peripheral edges 29 by seams 30'. Such material may preferably be a non-conductive plastic in which case the edges thereof may be welded together electronically. For
additional insulation and rigidity, it desired, a pair of smooth surface ozite boards (not shown) lg" thick, cut to approximately 1'71/2 x 11" may be used to sandwich the antenna therebetween. Provision is made in securing the material edges together, to allow the lead 22 to pass outwardly of the edges 29.
The dimensions indicated above are derived from mathematical computations for maximum efficiency for such antenna structures in compliance with ultra-high frequency operation as specified.
An antenna is derived by the ability of a structure to attract a given band of frequencies. The first consideration that must be given in designing an antenna is to make the electrical wavelength correspond to the physical length of the structure.
Equation 1 illustrates this consideration 468 670(mHz.)
The next consideration to be given is to provide a proper match to a 300' transmission line. The radiation resistance, antenna efliciency, directional pattern, and directive gain are not affected by the failure to match impedance. Matching merely makes it easier to get the available power from the antenna to the receiver, reduces the transmission loss, and lowers the maximum voltage stress in the transmission system.
To satisfy this requirement throughout a changing band of frequencies, two triangles were selected. The non-uniform cross-section with wider diameters at the bases provides broad band characteristics.
The angle of the triangles was derived by the relationships of Equations 2, 3, and statement 5 which follow below:
Equation 2 (simplified) Mfeet) X2L4 or 16.8 inches Equation 3 (simplified) A2 Z sin )1 Z=impedance300 ohms Equation 4 (simplified) Equation 5 (simplified) This equation illustrates how with the increased area of the triangles more energy can be intercepted. The result of higher gain is apparent, opposed to a thin wire reference dipole antenna.
DIRECTI'VE GAIN-gdb A=Area of Triangles-88 sq, inches summarizing the above disclosure it has been found that the horizontal and vertical polar patterns are the same, since the parasitic element is not included in the field. The reception has been increased to a maximum heretofore unachievable with an indoor UHF antenna.
Having thus described my invention, what I claim and desire to protect by Letters Patent of the United States of America, is:
1. An antenna for use in the ultra-high frequency range for television operation, said antenna comprising a pair of coplanar triangular metal laminae, the apieces of said triangular laminae being directed towards oneV another in spaced relationship, said triangular laminae having bases disposed parallel to each other, each of said apieces constituting a 70 angle, each of said bases being of a length of 11 inches, the perpendicular span between each of said apices and its respective base being 8 inches, a
two wire 300 ohm transmission line having a pair of wire ends secured to said laminae apices respectively, the free ends of said transmission line being provided with lugs for connection to antenna posts of a television receiver.
2. An antenna as claimed in claim 1, ibeing further provided with a closed envelope-like flat cover, enclosing said laminae, said cover having an opening for the passage of Said transmission line.
3. An antenna as claimed in claim 2, wherein said coverV consists of a pair of non-conductive plastic sheets having coextensive peripheral electronically Welded portions.
4. An antenna as claimed in claim 2, which is further provided with a pair of flat non-conductive sheets of material, said metal laminae being received therebetween, said metal laminae and said non-conductive sheets of material being enclosed in said cover.
References Cited UNITED STATES PATENTS 2,039,988 5/1936 Graves 343-872 2,614,220 10/1952 Doerner 343-702 2,632,849 3/ 1953 Fyler 343-702 2,673,931 3/1954 Stevens 343-873 2,750,321 6/19561 Koppelman 343-873 2,821,710 l/l958 Hale 343-720 3,369,245 2/1968 Rea 343-795 OTHER REFERENCES Canning: Inexpensive TV Antennas: Radio and Television News, April 1951, p. 128.
ELI LIEBERMAN, Primary Examiner U.S. Cl. X.R. 343-873