Closed form solution of an n-port microstrip planar disk device with an eccentrically located short circuit post of arbitrary radius

An analysis technique is presented and used to predict the performance of an n-port microstrip planar disk device with an arbitrarily located internal short-circuit post of arbitrary radius. The approach yields analytical expressions ideal for CAD implementation. The post may be of any radius providing it does not extend beyond the periphery of the disk. The technique allows the electromagnetic fields at the periphery of the disk to be altered by the appropriate choice of post size and offset. The experimental results are in very good agreement with the theoretical predictions.<>