Phased array antenna system with intermodulation beam nulling

1. A phased array antenna system comprising:

a nulling section interposed between a beam forming section and a feed chain section;

the nulling section configured to shift the phases of plural signals by a nulling angle with a magnitude of 90/N where N is the order of the intermodulation beam to be nulled;

an antenna having a plurality of radiators, each radiator coupled to a respective amplifier in the feed chain section;

each amplifier coupled to a respective nulling phase shifter in the nulling section;

each nulling phase shifter coupled to a respective steering phase shifter in the beam forming section;

one or more processors for activating the nulling and steering phase shifters; and,

the phased array antenna system configured to simultaneously

transmit a plurality of signals to respective locations.

2. The phased array antenna system of claim 1 further including:

one or more processors for calculating directivity patterns;

one or more memory devices for storing calculated directivity patterns;

a signal sampler for sampling fundamental and intermodulation forward and reflected traveling wave signal levels at the input of each radiator; and,

one or more processors for updating the stored directivity patterns in accordance with the sample values.

3. The phased array antenna system of claim 2 wherein a signal processor is used.

4. The phased array system of claim 2 wherein the one or more processors for activating the nulling and steering phase shifters comprise at least one beam forming section processor and at least one nulling section processor.

5. A method of nulling an intermodulation beam in a phased array antenna system comprising the steps of:

providing a nulling section interposed between a beam forming section and a feed chain section;

the nulling section configured to shift the phases of plural signals by a nulling angle with a magnitude of 90/N where N is the order of the intermodulation beam to be nulled;

providing an antenna having a plurality of radiators, each radiator coupled to a respective amplifier in the feed chain section;

coupling each amplifier to a respective nulling phase shifter in the nulling section;

coupling each nulling phase shifter to a respective steering phase shifter in the beam forming section;

activating the nulling and steering phase shifters with one or more processors; and,

the phased array antenna system simultaneously transmitting a plurality of signals to respective locations.

6. The method of claim 5 , further including the steps of: calculating directivity patterns with one or more processors;

storing calculated directivity patterns in one or more memory devices;

sampling with a signal sampler fundamental and intermodulation forward and reflected traveling wave signal levels at the input of each radiator; and,

updating the stored directivity patterns in accordance with the sample values with one or more processors.

7. The method of claim 6 further wherein the step of calculating directivity patterns is performed with a single processor.

8. The method of claim 6 further comprising the steps of:

utilizing separate processors to activate the nulling and steering phase shifters.

9. A phased array antenna system comprising:

a combined nulling and beam forming section coupled to a feed chain section;

the combined nulling and beam forming section configured to shift the phases of plural signals by a nulling angle with a magnitude of 90/N where N is the order of the intermodulation beam to be nulled;

an antenna having a plurality of radiators, each radiator coupled to a respective amplifier in the feed chain section;

each amplifier coupled to a respective phase shifter in the combined nulling and beam forming section;

a processor configured to combine a steering and a nulling phase shift, the combined phase shift applied to a respective phase shifter; and,

the phased array antenna system configured to simultaneously transmit a plurality of signals to respective locations.

10. A phased array antenna system comprising:

a nulling section;

the nulling section configured to apply a nulling phase distribution to signals passing therethrough; and,

the nulling phase distribution shifting the phases of plural signals by a nulling angle with a magnitude of 90/N where N is the order of the intermodulation beam to be nulled.