US2486872A

US2486872A - Receiving antenna

Info

Publication number: US2486872A
Application number: US651714A
Authority: US
Inventors: Verlois R Parker
Original assignee: HENRY H HIRVONEN; PAUL H PARKER
Current assignee: HENRY H HIRVONEN; PAUL H PARKER
Priority date: 1946-03-04
Filing date: 1946-03-04
Publication date: 1949-11-01
Anticipated expiration: 1966-11-01

Description

Nov. 1, 194

ARKER RECEIVING AflT-ENNA Filed March 4, 194 6 VENTOR. fimms Patented Nov. 1, 1949 UNITED STATES. PATENT OFFICE RECEIVING ANTENNA Verlois R. Parker, Lunenburg, Mass., assignor of one-third to Paul-.H. Parker and one-third to Henry H. Hirvonn, both of Fitchburg, Mass.

Application March 4, 1946, Serial No. 651,714 2 Claims. (crest-33) --The object of my invention is to provide an improved antenna system for the reception of high frequency horizontally polarized radio signals and more particularly for the reception of commercial radio broadcasts in the new very high frequency (VHF) spectrum.

A further object of the invention is to provide an improved antenna system for the above mentioned purpose which is non-directional in characteristic and which will receive radio signals equally well from any direction.

The present invention, as one of its objects, provides a simple, inexpensive means of matching the collector elements of the antenna to a conventional transmission line, which in turn serves to connect the antenna to the radio receiving equipment.

A further object of my invention is to provide an antenna for the above mentioned purpose which can be produced'easily and economically in quantity, shipped in knocked down form, and assembled and erected by inexperienced personnel.

Other objects and advantages of the invention will appear hereinafter.

Reference is to be had to the accompanying drawings, in which Fig. 1 is a view in side elevation;

Fig. 2 is a bottom plan view; and

Fig. 3 and 4 are diagrammatic views showing modifications of the invention.

Referring to Figs. 1 and 2, four rods or hollow tubes forming collector elements are indicated at Ill, l2, l4, and I6, each rod or tube being wavelength long at operating frequency. These rods or tubes are coplanar and 90 apart, and radially arranged about an axis defining the mast axis, with their adjacent ends separated. The rods form a pair of 90 dipoles mounted on and insulator It made to suit of any low loss material. I prefer to use a molded plastic such as polystyrene or fine grade porcelain. Screws or bolts 20 may be used to secure the rods or tubes in place.

As shown by way of illustration, a matching section 22 of twisted wire is connected at one end thereof to two wavelength collector elements It and [4 at A and A respectively, these elements being 180 apart. The other end of the wire section is connected to the two remaining collector elements l2, l6 at B and B The transmission line to the radio receiver is connected to the antenna at A, A The numeral 24 represents the mast which may be of wood, metal, etc.

As shown, the ends of each wire in the matching section are connected to two adjacent collector elements at .but each end of the matching section itself is arranged to be secured to collector elements at It is fundamental that maximum efficiency is obtained only when the antenna impedance matches the transmission line impedance, usually 70 ohms, and the matching section 22 provides this balance.

The wavelength collector elements each have an equivalent impedance of 35 ohms. If adjacent rods or tubes I0 and l2, l4 and I6 were to be connected in series, the resulting impedance would be 70 ohms at the junction of each of the two so connected elements. Placing the two adjacent rods or tubes thus connected, in the same magnetic field effectively connects them in parallel making the resultant impedance 35 ohms for the four collector elements. 35 ohms is not a standard impedance for commercial transmission line, and I employ the matching section wire or similar means to raise this value to a sufficient impedance to match the transmission line, which has an impedance of '70 ohms.

It is therefore the purpose of matching section 22 to connect the collector elements l0, It in parallel with collector elements l2, I6 and also to raise the impedance of the dipole formed by rods l2, IE to a sufficient value so that the resulting impedance when connected in parallel with the dipole formed by rods I0, M will be very close to the desired 70 ohm value. Using standard 70 ohm twisted pair line for this matching section a length approximately wavelength long is correct. However, it is possible to use any twisted pair of a value above or below 70 ohms and the length required will vary a small amount plus or minus the /8 wavelength for optimum results.

In Fig. 3, the construction is the same but I use a coaxial cable 26 instead of the matching section 22 to illustrate that any other electrical conductors may be used to raise the impedance as long as the values are such as to obtain the desired result.

Fig. 4 shows a modification wherein rods or

tubes

28, 30, 32, 34 are present with the

adjacent collectors

28, 30 and 32, 34 electrically joined by

connectors

36 and 38 respectively, the latter being connected by lines 40, 42 to a variable autotransformer which may increase the impedance as desired according to its setting.

From the foregoing explanation it can be seen that the antenna consists essentially of four rods A wavelength long located co-planar and spaced 90 apart which form two half-wave dipoles 90 apart, connected in parallel by electrical means also providing for matching the relatively low impedance of the antenna to a transmission line of a higher value of impedance.

Since it would be apparent to one skilled in the art, were this antenna to be used for transmitting, the currents in each dipole would have to have a certain time-phase element with respect to each other but since a receiving antenna in free space only sees a rising and'falling mag-- netic field the phasing of the currents in each dipole is of no concern. 1

Having thus described my invention and tn advantages thereof, I do not wish to be limited to the details herein disclosed, otherwise than as set forth in the claims, but What 1 claim is:

1. High frequency receiving antenna comprising four co-planar rod-like collectors angular-1y spaced at 90 and a pair of separate electrical connectors, said pair together having two opposite ends, one end being separately connected to two collectors at 180 apart, the other end being separately connected to the other two col- 4 lectors, each separate connector connecting collectors at 90 apart.

2. The antenna of claim 1 wherein the pair of connectors is of a definite predetermined impedance raising the antenna impedance to a desired factor.

VERLOIS R. PARKER.

REFERENCES CITED The following references are of record in the tile of this patent:

UNITED STATES PATENTS Number Name Date 2,997,491 Lair Nov. 2, 1937 2,110,278 Shaw Mar. 8. 938 2,116,734 Reinartz May 10, 1938 2,135,344 Johnston Nov. 1, 1938 2,245,693 Lindenblad June 17, 1941 2,280,738 Bace Apr. 21, 1942 2,358,520 Landon Sept. 19, 1944 2,364,084 Martin Dec. 5, 1944 2,374,271 Brown Apr. 24, 1945 2,410,597 Brown Nov. 5, 1 946 2,420,967

Moore May 20, 1947