Investigation of interference suppression radome for microstrip arrays

New design concepts are described for improving the performance of a cheap, lightweight radome cover for facilitating interference suppression, in particular for microstrip antennas. The antenna structure presented consists of a microstrip planar array fitted with a lossy sheet and separated by a foam spacer. The spacer thickness is crucial to the design and must be chosen such that d+h is a multiple of λ/2 to ensure that any loss in antenna gain is minimised at the antenna transmission frequency. The lossy sheet gives some useful isolation properties for out-of-band interference but gives no protection at the transmission band. Therefore it is important that this null is limited to a narrow bandwidth and that the antenna radiation pattern is largely unaffected by the radome presence