Abstract: A patch antenna includes a ground plane surrounded by a wall defining a cavity. A radiating element is disposed within the cavity substantially parallel to the ground plane and separated from the ground plane by a composite dielectric including an air gap. An excitation probe is electrically connected to the radiating element for exciting at least a dominant mode of the radiating element. The radiating element includes an annular slot surrounding the excitation probe and defining a capacitive load for compensating an inductance of the excitation probe.

Abstract: A system provides evaluation of stability of an on-frequency repeater. A unique signature is imposed on RF signals transmitted by the repeater, and RF signals received by the repeater are analyzed to detect signal components corresponding to the signature. The signature signal is composed of a sequential series of signal pulses separated by a quiescent period. Respective transmit and quiescent power levels of signal components of the input signal received by the repeater are detected. These power levels are then used to estimate the system stability.