US2051260A - Radio receiving antenna circuit - Google Patents

Description

Aug. 18, 1936.

L. J. LESH RADIO RECEIVING ANTENNA CIRCUIT Filed June 18, 1934 Patented ug. 18, Q

UNITED STATES PATENT OFFICE Y 2,051,260 RADIO RECEIVING ANTENNA CIRCUIT Application June 1s, 1934, serial No. 731,025

.4 Claims.

My invention relates in general to improved radio receiving antenna circuits, and more specically to an improved circuit arrangement and interconnection of radio receiving antenna the object of which is to improve the selectivity thereof and to neutralize or reject interfering Waves and prevent them from interfering with the Wanted signals.

In order to attain this object I have shown as an example one circuit arrangement having various devices shown in proper relationship and adjustable to meet various conditions. In general the arrangement shown consists of a plurality of antenna branches, connected together at a common point. One branch has the radio receiving set coupled thereto in the usual manner, while the other branches include suitab-le variables of resistance, capacity and inductance with ground shunts therefrom through variable resistances. The arrangement shown may be utilized to neutralize or reject interfering waves from Various sources and I have shown the method of neutralizing interference emanating from a telephone line by substituting a telephone circuit for one of the antenna branches. It will be understood that interference may arise from various causes such as electrical machinery, power lines and such interference may arise from devices located at various points relative to the radio circuit. Therefore I have shown certain connecting switches in the drawing for cutting out or switching certain of the elements in order to meet the requirements of a particular instance. In other words, for certain interfering waves it may be found necessary to disconnect certain or all of the ground shunts while in other instances it will be found preferable to close such shunts.

In the accompanying drawing consisting of a single iigure I have shown three branched antenna circuits converging at a common point designated at X. The antenna branch A includes a suitable coupling L L4 to the radio receiving set RR, this coupling and also the radio receiving set may be of any commonly used type although I prefer a coupling of the inductive type to an ungrounded receiving set. The branch antenna A2 has in series therewith a resonant circuit including inductance L2, capacity C2 and resistance R1, adjustable to the received frequency. This resonant circuit is connected to ground through a variable resistance R5 and a disconnecting switch SW2. In addition branch A2 is connected to the arm of switch SW1 through which this branch may be connected to the an- (Cl. Z50-20) shunt condenser C4. The line 'IL is, of course, 5

bridged by the usual substation instrument circuit including talking and listening instrumentalities as indicated at T. In use the telephone line when connected to this circuit acts as one of the antenna branches and is Substituted for branch A4. Branch antenna A3 has in series therewith another resonant circuit comprising either a variable resistance R4 and a variable capacity C3 or the variable inductance L3 with the capacity C3 Adependent on the posi- 15 tion of a switch SW3. In addition to the resonant circuit this antenna branch A3v also has a shunt to ground through a disconnecting switch SW4 and a variable resistance R6.

The variable shunt resistances involved should be variable from 0 to 1,000,000 ohms non-inductive resistance, while the inductances capacities and resistances in the resonant circuits will be chosen in values appropriate to the frequency of the received radio signals and such values are Well known to those conversant to the art.`

It is desirable to have the antenna branches of the same effective electrical length and to have these branches arranged symmetrically in the same plane although the physical arrangement admits of wide variation. It is also desirable to have variable coupling between the inductances L2 and L3 in the two resonant circuits.

By a proper selection and adjustment of the various components of this arrangement it has been found possible to effectively neutralize or eliminate from the radio receiving set the interference emanating from a nearby source, of a magnitude comparable with the incoming radio Waves. This neutralization permits clear and undisturbed reception of a desired radio signal under conditions where reception by a simple radio antenna is impossible. It has been found possible to completely balance out the beat or heterodyne note produced by an oscillator in the vicinity of the radio receiver against an incoming radio carrier wave, under conditions where conventional set-ups would render reception impossible. It has also been found that proper adjustments of the components of my improved antenna system will also demonstrate useful directive sensitivity and sensibility.

It will be understood that in practice the selection and adjustments of the antenna components is determined by tests to meet the con- In this instance, space limitation dictated thatl the antenna arms A1 and A2 of my arrangement be not longer than ten feet {andthat they be placed almost parallel and about two feet apart. Under these conditions it was found by experiment that the best results were obtained by closing switch SWl to branch A4, closing switch'SWZ' so that a shunt to ground of about 100,000 ohms resistance was obtained,closing switch SW3 to connect up inductance L3, and closing switch SW4 and adjusting resistance R6 tominimize resistance or direct to ground. The variabler cornponents were then adjusted until interference was eliminated and satisfactory radio reception was provided at the desired wave length.

Having described the general arrangement and features 4of my invention, what I consider to be novel and desire to have protected by Letters Patent'will be pointed out in the appended claims.

What is claimed is: y 1. A radio receiving antenna system comprising a plurality of antenna branches connected ktogether at a common point, a radio receiver coupled to one branch, Aa telephone circuit included in another branch together with means ditions imposed by local conditions such as the for controlling the resonance and phase thereof at radio frequency, and phase and resonance control means included in a third one of saidV branches.

2. In a radio receiving antenna system, .a plurality of antenna branches radiating from a common point, a radio receiving set coupled to one ponents and shunts adjustable to eliminate interference in the receiving set due to oscillations "from an interfering source.

3. Ina radio receiving antenna system, a plurality of antennas, a circuit .connecting one antenna to a common point, a radio receiving set coupled to said circuit between the antenna and the common point, a circuit connecting each of the other antennas to the common point, a resonant circuit in each of said other circuits between the respective antennas vand the common point, and circuits for connecting each of said other antennas to ground through a variable resistance independent of said resonant circuits.

ll. In a radio receiving antenna system, a pair of antenna branches connected together at a common point, each branch connected to the common point through a resonant circuit having means for controlling the resonance and phase thereof, a telephone circuit also connected to said common point through a similar resonance circuit, a variable ground shunt for said telephone circuit, and a radio receiving set coupled to one of said branches.

' LAURENCE J LESI-I.

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