Plural mast-mounted antennas selectively deenergizable
US 3124802 A
Description (OCR text may contain errors)
March 10, 1964 G. VON DALLARMI PLURAL MAST-MOUNTED ANTENNAS SELECT'IVELY DEENERGIZABLE IN GROUPS WITHOUT Filed June 5, 1962 Fig.2
DESTRUCTION OF RADIATION PATTERN 2 Sheets-Sheet 1 Fig.3
March 10, 1964 VON DALL'ARN" 3,124,802
PLURAL. MAST-MOUNTED ANTENNAS SELECTIVELY DEENERGIZABLE IN GROUPS WITHOUT DESTRUCTION OF RADIATION PATTERN Filed June 5, 1962 I 2 Sheets-Sheet 2 United States Patent 3,124,802 PLURAL MAST-MOUN TED ANTENNAS SELEC- TIV ELY DEENERGIZABLE IN G R 0 U P S WITHOUT DESTRUCTION 0F RADIATION PATTERN Georg von DallArmi, Erding-Klettham, Germany, as-
signor to Siemens & Halske Aktiengesellschaft, Berlin and Munich, a corporation of Germany Filed June 5, 1962, Ser. No. 200,088 Claims priority, application Germany June 28, 1961 6 Claims. (Cl. 343876) The invention disclosed herein is concerned with a high gain antenna comprising a plurality of radiators preferably arranged vertically successively upon a mast, said radiators operating with respect to the same operating frequency and being insofar as the feed thereto of high frequency energy is concerned, subdivided into at least two groups which are operatively individually and independently connectible.
It is known to arrange a plurality of radiators side by side or in vertically superposed manner, for the purpose of obtaining in pronounced directional characteristic. The radiators are subdivided into individual independently operatively connectible groups in order to avoid disconnection of the entire installation in the event of interruptions in the operation or incident to carrying out maintenance work on the antenna.
In a known antenna of this kind, one group is arranged at the upper part of the mast while the other group is disposed at the lower part thereof. When there is only one group of radiators operating in such an antenna, there will be obtained a radiation diagram or characteristic which is considerably different from the one that is obtained incident to joint operation of both groups. Such changes in the radiation diagram become particularly troublesome in the case of ultra short wave or television broadcasting employing omnidirectional antennae or antennae radiating in preferred sectors, because in some situations there appear in the receiving region null points of the directional characteristic in the vertical plane, impeding the uniform supply of high frequency energy to the respective region.
The object of the invention is primarily to avoid these difficulties in a manner as simple as possible and to obtain as far as possible identical radiation characteristics for the entire antenna as well as for the operation of individual antenna groups.
According to the invention, which is concerned with an antenna of the initially indicated kind, this object is achieved by distributing along the mast the radiators of the individual groups in a mixed arrangement, such that radiators of one group are alternately followed by radiators of another group or groups. Accordingly, the disconnection of one group of radiators of an antenna constructed as proposed by the invention does not anymore inactivate the entire upper or lower part of the array but only the individual radiators of the respective disconnected group which lie between the radiators of other groups. This measure results in a considerable improvement of the radiation diagram with respect to spatially combined groups, thereby particularly avoiding the appearance of pronounced null points already at small angular values below the horizontal. The radiators of the individual groups are advantageously uniformly distributed over the entire region of the mast which is occupied thereby.
In the event that an antenna comprises, instead of individual radiators, a plurality of radiator units combined to form so-called dipole fields, a plurality of which fields are so far as the feed thereof is concerned, combined in a group, there may likewise be achieved an improvement of the radiation diagram by a mixed arrange ment of the dipole fields of the respective individual groups. The arrangement of the individual fields is thereby advantageousl-y so effected that dipole fields of the various groups alternate.
Further details of the invention will appear from the description which is rendered below with reference tothe accompanying drawings showing a sender antenna operating respectively for ultra short wave and television broadcasts, and also indicating the feed or supply of high frequency energy thereto.
FIGS. 1 and 2 shows an antenna in diagrammatic elevational side view and in top view, respectively;
FIG. 3 indicates the manner in which the radiators are combined in groups and also the feed of high frequency energy thereto;
FIG. 4 represents the relative field strength curves resulting in the customary operation of radiator groups; and
FIG. 5 shows the relative field strength curves resulting in the operation of radiator groups arranged according to the invention.
Referring now to FIGS. 1 and 2, numeral 1 indicates the mast which is equipped with dipole fields 2 to 9, each field comprising dipoles which are arranged about the mast so as to obtain a horizontal omni-directional radiation diagram. Each dipole field comprises, for example, four vertically successively arranged horizontally polarized dipoles.
The supply or feed of the high frequency energy for the individual fields is apparent from FIG. 3. The dipole fields 2, 4 and 6, 8 are connected in parallel over lines 10 and 11 which are in turn extended to a common distributor 15 over the lines 12 and 13. The remaining dipole fields 3, 5 and 7, 9 are over lines 16 and 17 likewise connected in parallel and the lines 16, 17 are over lines 18 and 19 extended to the common distributor 20.
The dipole fields 2, 4, 6 and 8 are supplied with high frequency energy over the switch 23 and the line 21 while the dipole fields 3, 5, 7 and 9 are supplied over the switch 23 and the line 22. The switch 23 is connected with the sender 24 over the common high frequency line 25. The lines 21 and 22 extending from the switch 23 to the dipole fields 2 to 9 are of different length in order to obtain a dropping of the radiation maximum and filling of the null positions.
The antenna accordingly comprises two identical groups which are independently supplied with high frequency energy and which can be respectively independently individually operatively connected and disconnected.
FIG. 4 shows the relative field strength of the antenna in dependence upon the angle 6 (vertical characteristic) which is indicated in FIG. 1, it being assumed thereby that dipole fields 6 to 9 in the upper half of the antenna form, as customary until now, one group while the dipole fields 2 to 5 in the lower half of the antenna are combined to form another group. The full line curve 25 represents the course of the relative field strength in dependence upon the angle 5, when both groups are in operation at the same time. The dash line curve 26 represents the course of the field strength resulting when only the dipole fields 6 to 9 in the upper antennna half are operative, and the dot-dash curve 27 indicates the course of the field strength resulting when only the dipole fields 2 to 5 of the lower half of the antenna are operative. It will be seen that the field strength course according to curves 26 and 27 deviates appreciably from the conditions obtaining in normal operation, as represented by the curve 25, and that the supply of the re ceiving region is not satisfactorily assured. Attention is particularly called to the fact that the maximum which, due to the elevated positioning of the antenna, should appear at an angle of about one degree below the horizontal, is in the case of partial operation strongly shifted respectively upwardly and downwardly.
FIG. 5 shows the course of the relative field strength in dependence upon the angle 6 when the supply of high frequency energy to the antenna is effected according to the scheme indicated in FIG. 3. It will be seen that the vertical characteristic represented by the full line curve 28, appearing incident to the joint operation or both antenna groups, hardly differs, particularly in the main radiation region, from the characteristic resulting incident to the operation of a part of the antenna, as represented by the dash line curve 29. The fact that the characteristics resulting from the operation of both partial antenna elements are identical, is of particular importance.
The invention is not inherently limited for use with the described and illustrated antenna arrangement but may be employed in connection with a greater number of groups and different arrangement of the radiators.
Changes may be made within the scope and spirit of the appended claims which define what is believed to be new and desired to have protected by Letters Patent.
1. A high gain antenna comprising a plurality of radiators arranged, for operation with identical frequency, vertically successively upon a mast, said radiators being subdivided to form at least two independent groups which are individually independently operatively connectible, the subdivision of said radiators being such that radiators of the respective groups are along the mast distributed '4 in mixed manner with radiators of one group alternately followed by radiators of another group.
2. An antenna according to claim 1, wherein the radiators of each individual group are uniformly distributed with respect to the entire region of the mast occupied by the radiators.
3. An antenna according to claim 2, wherein the respective groups are built up by a plurality of dipole fields which are alternately successively disposed along the mast.
4. An antenna according to claim 3, employed as a sender antenna for the transmission of ultra short wave and television programs.
5. A high gain antenna comprising a mast, an array of radiators disposed vertically successively on said mast, means for combining said radiators in at least two groups, each group comprising pairs of radiators overlapping radiators of the other group in the upper and lower part of the antenna, respectively, a common distributor for each group, a connect-disconnect switch common to said distributors, for selectively operatively connecting the radiators of each group, and circuit means common to said switch for supplying high frequency energy to each group of radiators.
6. An antenna according to claim 5, comprising line means of different length extending from said common switch to said distributors for supplying high frequency energy to the respective groups of radiators.
No references cited.