Finite-width conductor-backed coplanar waveguide-fed circularly polarized side-plane antenna

The coplanar waveguide with a lower ground plane forms the conductor-backed coplanar waveguide (CBCPW). Due to the lower ground plane, the mechanical strength and heat-sinking capability of the conventional coplanar waveguide are improved. In practice, the substrate and the ground planes of the CBCPW are usually of finite width. The CBCPW mode and the microstrip-like mode coexist in the finite-width CBCPW. Both of them have zero cutoff frequency. The phase velocity of the microstrip-like mode (MSL) is slower than the CBCPW mode. Therefore, the MSL mode takes power away all the time. The leaky MSL mode causes the resonances of the side-plane conductors. The transmitted power is reduced by the reflected and radiated power when the side-plane conductors resonate. The unwanted radiation maybe degrades the performance of the finite-width CBCPW-fed antenna unless through-plated vias are placed at the inner edges of the side-plane conductors. Using through-plated vias increases the manufacturing cost. With proper design, the side-plane conductors fed by finite-width CBCPW can form a simple, vialess, unidirectional, and linearly polarized antenna. In this paper, a compact finite-width CBCPW-fed circularly polarized (CP) side-plane antenna is proposed.