US3035266A - Broad band active element for television arrays - Google Patents

Description

May 15, 1962 BROAD BAND ACTIVE ELEMENT T. A. MARSHALL FOR TELEVISION ARRAYS Filed May 25, 1958.

IN VEN TOR.

United States Patent G 3,035,266 BROAD BAND ACTIVE ELEMENT FOR TELEVISION ARRAYS Thomas Albert Marshall, 5243 E. Falls View Drive, San Diego, Calif. Filed May 23, 1953, Ser. No. 737,452 1 Claim. (Cl. 343-799) The herein disclosed invention relates to an active element having wide band performance, particularly for use in television antenna arrays.

A principal object of my invention is to provide a new and improved active element having uniform gain over the present television channels.

It is well known that'a folded dipole has a loss in gain for reception of frequencies above and below the resonant frequency. Thus, a resonant folded dipole for channel 2 has a loss of 3 decibels for channel 5. In recently developed television arrays, two folded dipoles of unequal lengths are used to reduce this serious loss. Horizontally arranged dipoles for low television band are very poor collectors for the high band channels unless they are V-shaped or folded for a given length at the center or at the quarter points to eliminate the clover leaf pattern. The present invention eliminates the foregoing disadvantages because part of the length of each collector is included in the circular part which acts in the same way as for folding a portion of the dipole to eliminate the clover leaf effect.

The FIGURE is a vertical cross sectional view of an improved television antenna constructed in accordance with the invention.

Referring to the drawing, the complete assembly is designated generally at 1. 7 is a circular part, having a circumference of 63% inches, being the length around the circumference from feed points 22. The circular part is open circuited at 2-2 to provide feed points for connecting a transmission line 8. The active element should be mounted vertically.

3A to 6A and 313 to 6B inclusive are collector arms extending outwardly on each side with their inner ends being connected to the circular part.

The arms of the various collector elements are unequal in lengths. 3A and 3B are resonant to channels -6, 4A and 4B are resonant to channel 4, 5A and 5B are resonant to channel 2, while 6A and 6B are resonant to the mean center of the high television band. This is a significant feature of the invention. The longer collector arms are also resonant on the third harmonics of the high frequency television channels.

The lengths from 2 to 3 plus 3A being equal to a quarter wave length for channel 5. The lengths from 2 to 3 plus 3B being also equal to a quarter wave length for channel 5. The arms 3A and 3B together with the included lengths along the circular part from 2 to 3 form a half wave length collector which is resonant to channel 5. The length being short enough to be a resonant collector for channel 6. 244A and 2-44B form a resonant half wave length collector for channel 4. 2-55A and 2-55B form a resonant half wave col lector for channel 2. 26-6A and 2-66B form a full wave collector resonant at the mean frequency of the high television band.

3,935,256 Patented May 15, 1962 Table 0 Element Lengths Lower Second Third Fourth Rods Rods Rods Rods 3A and 3B 4A and 4B 5A and 53 6A and 6B 32/! 34/! 38% 9% Feed point spacing 2-2 is one inch.

9 is an insulator which may also serve as a mounting support for securing the active element to a boom. Point 10 is at zero potential and may be connected to a boom. 8 is a 300 ohm line.

Parasitic elements are most effective when placed in line with feed points 2-2.

It will also be apparent that various modifications may be made to the construction of the active element utilizing the principles of my invention. It is therefore to be understood that within the scope of the appended claim the invention may be practiced otherwise than as specifically described.

What is claimed is:

A broad-band television active element comprising a circular part disposed in a vertical plane and having an open circulated feed point at the lower part of the said circular part and a plurality of arms extending outwardly on each side of said circular part with their inner ends being connected to the said circular part, the lower right and left hand rods of said arms are connected to corresponding positions from the feed point of said circular part to form a one-half wave length resonant at the extreme edge of the high frequency side of the low television band, the second right and left-hand rods of said arms are connected to corresponding positions from the feed point of said circular part to form a one-half wave length resonant at the center of the low frequency side of the low television band, the third right and left hand rods of said arms are connected to corresponding positions from the I References Cited in the file of this patent UNITED STATES PATENTS 1,933,941 Taylor Nov. 7, 1933 2,192,187 Gordon Mar. 5, 1940 2,192,532 Katzin Mar. 5, 1940 2,227,088 Hollmann Dec. 31, 1940 2,657,312 Saranga Oct. 27, 1953 2,658,144 Kearse Nov. 3, 1953 FOREIGN PATENTS 520,849 Great Britain May 6, 1940

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