Microstrip Patch With Grounded Spikes: A New Technique to Discriminate Orthogonal Mode for Reducing Cross-Polarized Radiations

This work explores an idea of modifying surface current distribution in a rectangular microstrip patch which contributes to reducing its H-plane cross-polarized (XP) radiations along with minimizing the backside radiation to some extent. A pair of grounded spikes has been strategically used and the physics behind its operation in weakening the XP generating TM02 mode has been thoroughly discussed. The vertical height of the spike is typically
$\lambda $
/4 and a further investigation demonstrates shortening of its effective height by folding the same by 90°. A set of prototypes has been experimentally studied to ensure the predicted characteristics viz. the 12 dB consistent suppression of XP level over the whole range of elevation in H-plane and an average of 5–7 dB suppression in backside radiation. These achievements are also associated with more than 1 dB improvement in peak gain. The design is straightforward, low cost, and commercially viable. The nonplanar feature restricts its use only to those applications where antenna front is open or can accommodate the vertically extended or 90° bent spikes.