| 摘要 |
Patch antenna systems for half-duplex communications which are capable of providing a positive gain, quasi-hemispherical antenna pattern over widely separated transmit and receive frequency bands. The antenna systems according to the present invention generally comprise a patch antenna, transmit and/or receive circuit branches for tuning the patch antenna to resonate in separate transmit and receive frequency bands, and disconnection means for electrically isolating the transmit circuit branch from the antenna during periods of reception and for electrically isolating the receive circuit branch from the antenna during periods of transmission. Matching means, which preferably are implemented as part of the transmit and receive circuit branches, may also be provided for increasing the operating bandwidth of the antenna in both the transmit and receive frequency bands. In a preferred embodiment, the patch antenna transmits and receives circularly polarized waveforms, and may be fed by a single feed or in quadrature via orthogonally located feed points. |
