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

Abstract

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 [1]. 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 [2]-[3]. 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 [4]. 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 [5]. 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 [6]. In this paper, a compact finite-width CBCPW-fed circularly polarized (CP) side-plane antenna is proposed.