Feed networks for self-interference cancellation
AssigneeThe Florida International University Board of Trustees
InventorsSatheesh Bojja Venkatakrishnan, John L. Volakis
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Abstract
Feed networks and methods of using the same to achieve high levels of self-interference cancellation (SIC) in Simultaneous Transmit and Receive (STAR) systems are provided. SIC at the antenna feed network alone can be as high as 100 dB. This can be done by employing entirely low-cost, low-profile passive circuits. The feed network creates a perfect anti-phase path that cancels the high power self-interference signal at the receive port.
Claims20
A feed network to enhance self-interference cancellation, the feed network comprising:
- a first circulator;
- a second circulator connected to the first circulator;
- a third circulator connected to the first circulator;
- a hybrid-180° coupler connected between the second circulator and the third circulator;
- and
- a ferrite isolator connected between the first circulator and the second circulator.
A feed network to enhance self-interference cancellation, the feed network comprising:
- a first circulator;
- a first hybrid-180° coupler connected to the first circulator;
- a second circulator connected to the first hybrid-180° coupler;
- a third circulator connected to the first circulator;
- a second hybrid-180° coupler connected between the fourth circulator and the third circulator;
- a third hybrid-180° coupler connected between the second hybrid-180° and the second circulator;
- a fourth circulator connected to the first hybrid-180° coupler and the second hybrid-180° coupler;
- and
- a ferrite isolator connected between the first hybrid-180° coupler and the second circulator.
A Simultaneous Transmit and Receive (STAR) system, comprising:
- an antenna;
- a radio transceiver;
- and
- a feed network connected between the antenna and the radio transceiver,
- the feed network comprising:
- a first circulator;
- a first hybrid-180° coupler connected to the first circulator;
- a second circulator connected to the first hybrid-180° coupler;
- a third circulator connected to the first circulator;
- a second hybrid-180° coupler connected between the fourth circulator and the third circulator;
- a third hybrid-180° coupler connected between the second hybrid-180° and the second circulator;
- a fourth circulator connected to the first hybrid-180° coupler and the second hybrid-180° coupler;
- a ferrite isolator connected between the first hybrid-180° coupler and the second circulator;
- a first attenuator connected between the first circulator and the third circulator;
- a second attenuator connected between the first hybrid-180° coupler and the fourth circulator;
- and
- a tunable external multi-tap matching network connected to the fourth circulator,
- a port of the third circulator being terminated with a first 50Ω load,
- a sigma port of the first hybrid-180° coupler being terminated with a second 50Ω load,
- a delta port of the second hybrid-180° coupler being terminated with a third 50Ω load,
- a delta port of the third hybrid-180° coupler being terminated with a fourth 50Ω load,
- the first circulator being configured to receive a first input to the feed network from the radio transceiver,
- the third hybrid-180° coupler being configured to send a first output from the feed network to the radio transceiver, and
- the second circulator being configured to receive a second input to the feed network from the antenna and to send a second output from the feed network to the antenna.
Dependencies are inferred from the claim text.