Method and apparatus for controlling the directivity pattern of an antenna

Claim 2

A direction finder antenna system having controllable directional characteristics comprising: an antenna having a characteristic impedance and having first and second ends; a load adapted to function as an antenna terminating impedance and having an impedance different from the said characteristic impedance, the antenna system having different directional characteristics for different impedance values of said load; antenna utilization means; and means connecting said antenna utilization means to one of the first and second ends of the antenna and said load to the other of the first and second ends of the antenna.

Claim 3

The antenna system of claim 1 further comprising a second load adapted to function as an antenna terminating impedance and having an impedance different from the said characteristic impedance, the antenna system having different directional characteristics for different Values of said load, and means for periodically interchanging the ends of said antenna to which said utilization means is connected and for connecting one of said loads to the end of said antenna opposite the utilization means.

Claim 4

The antenna system of claim 2 further comprising means for independently varying the impedance of each said load to vary the directional characteristics of the antenna system.

Claim 5

An antenna system comprising: an antenna having a characteristic impedance and having first and second ends; antenna utilization means; first and second loads each having a variable impedance different from the said characteristic impedance to thereby permit the directional characteristics of the antenna to be varied; a square wave generator having a frequency substantially less than the frequency to be received by the antenna system; first, second, third and forth semi-conductor devices, the first and second semi-conductor devices being connected in series between the antenna ends and having their common point connected to said utilization means, the third and forth semi-conductor devices each connected to a respective one of the antenna ends and to a respective one of the first and second loads and adapted to be switchably biased by the said square wave generator one to a conducting state and the other to a non-conducting state whereby one said variable impedance means is coupled by way of the third semi-conductor device to one of said antenna ends and the utilization means is coupled by way of the second semi-conductor device to the other of said antenna ends when said second and third semi-conductors are biased to their conducting state by the square wave generator and the other of said variable impedance means is coupled to the other antenna end by way of the forth semi-conductor device and the utilization means coupled by way of the first semi-conductor device to said one antenna end when the first and forth semi-conductor devices are biased to their conducting state by the square wave generator.

Claim 6

An antenna system comprising: an antenna having a characteristic impedance and having first and second ends; antenna utilization means; first and second loads each having a variable impedance different from the said characteristic impedance to thereby permit the directional characteristics of the antenna to be varied; a square wave generator having a frequency substantially less than the frequency to be received by the antenna system; first, second, third and forth semi-conductor devices, the first and second semi-conductor devices being connected in series between the antenna ends and having their common point connected to said utilization means, the third and forth semi-conductor devices each connected to a respective one of the antenna ends and to a respective one of the first and second loads and adapted to be switchably biased by the said square wave generator one to a conducting state and the other to a non-conducting state whereby one said variable impedance means is coupled by way of the third semi-conductor device to one of said antenna ends and the utilization means is coupled by way of the second semi-conductor device to the other of said antenna ends when said second and third semi-conductors are biased to their conducting state by the square wave generator and the other of said variable impedance means is coupled to the other antenna end by way of the forth semi-conductor device and the utilization means coupled by way of the first semi-conductor device to said one antenna end when the first and forth semi-conductor devices are biased to their conducting state by the square wave generator.

Claim 7

A symmetrically switchable variable impedance antenna loading circuit comprising: a series circuit of four diodes adjacent ones of said diodes being coupled anode to cathode; an antenna having a first end connected to a first junction between the first and second diodes and a second end connected to a second junction between the third and fourth diodes; at least two variable impedance means, one coupled between the cathode of the first diode and a point of reference potential and the other coupled between the anode of the fourth diode and said point of reference potential; means coupling a third junction between the second and third diodes to an antenna utilization device; and means for periodically varying the potential at said first and second junctions.

Claim 8

A symmetrically switchable variable impedance antenna loading circuit comprising: a series circuit of four diodes adjacent ones of said diodes being coupled anode to cathode; an antenna having a first end connected to a first junction between the first and second diodes and a second end connected to a second junction between the third and fourth diodes; at least two variable impedance means, one coupled between the cathode of the first diode and a point of reference potential and the other coupled between the anode of the fourth diode and said point of reference potential; means coupling a third junction between the second and third diodes to an antenna utilization device; and means for periodically varying the potential at said first and second junctions.

Claim 9

The antenna loading circuit of claim 5 wherein said means for periodically varying comprises a square wave oscillator having an output frequency substantially less than the frequency to be received by said antenna; and radio frequency choke means coupling said square wave oscillator to said first and second junctions, the impedance of said radio frequency choke means being relatively high at the frequencies to be received by said antenna and relatively low at said square wave oscillator frequency.

Claim 12

The method of claim 7 further comprising the step of varying the impedance of said load.

Claim 13

The method of claim 8 further comprising the step of periodically inTerchanging the ends of said antenna to which said utilization device and the load are connected.

Claim 14

The method of claim 7 further comprising the step of periodically interchanging the ends of said antenna to which the load and said utilization device are connected.

Claim 17

The method of claim 11 wherein each said impedance is varied to improve the resolution capabilities of said system.