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A novel broadband RHCP/LHCP reconfigurable patch antenna array using an E-shaped patch antenna element is investigated. By applying Particle Swarm Optimization, a 17% S11-AR bandwidth was achieved and verified through measurement for the isolated element using MEMS switches at an overall substrate thickness of 0.092λ0. The achieved bandwidth is significantly higher than the current state-of-the-art in single-layer, single feed CP patch element designs with similar substrate thickness. A small percentage of the upper frequency band experiences a pronounced beam squint similarly to other thick substrate CP patch antennas. To overcome the beam squint, a novel rotated-element configuration is implemented to force pattern symmetry. Derivations of pattern symmetry and network effects are also shown. The final design prototype using rotated elements provides a measured 20% S11-AR bandwidth with good radiation pattern stability.

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Supporting circular polarisation in single‐layer, single‐feed, compact patch antennas is a challenging task, especially when improved bandwidths are required. The difficulty lies in simultaneously obtaining good axial ratio (AR) and impedance matching performance over the required bandwidth. Several broadband,thick‐substrate circularly polarised (CP) patch designs have appeared in the literature, but their complex fabrication might not be suitable for harsh environments requiring mechanical simplicity or for high‐frequency applications at X‐band or higher. In this study, the authors propose a novel solution to this problem: the CP half E‐shaped patch antenna. This antenna is able to utilise thick substrates to meet the bandwidth requirements of many potential applications. Furthermore, the design can be fabricated on a single‐layer and uses reasonably sized gaps and line widths, making for a fabrication‐friendly design. Their design example shows 5.3% AR and impedance matching bandwidth at a thickness near a tenth of a wavelength. The S11 < − 10 dB bandwidth is 35%. Their particular design example has dimensions that fit within 45% × 39% of a free‐space wavelength. Furthermore, they provide an important comparison discussing the differences in operation between the linearly polarised half E‐shaped patch, CP E‐shaped patch, and CP half E‐shaped patch.

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