Understanding the radiation pattern anomalies in the broadband CP reconfigurable E-shaped patch

Recently a CP reconfigurable E-shaped patch antenna was proposed for broadband use with over 17% AR-S₁₁ bandwidth. However, it has been observed that beam squints begin to appear in the upper frequencies of the band of operation. This paper reveals these beam squints and provides some insight into their origin. We investigate these beam squints by examining their aperture near-fields and show that these squints result from the excitation of a mode similar to the rectangular TM₁₁ mode.