Conductor-Backed Coplanar Waveguide Slotted Antenna Array with Improved Aperture Efficiency
Conductor-backed coplanar waveguide (CBCPW) propagates electromagnetic waves via dominant modes (coplanar waveguide mode), and excites leaky wave which propagates toward both sides despite the value of the frequency. In general, there are two applications based on this structure: first is to use such property to design the antenna; the other is to suppress the leaky wave through some methods in order to decrease the unnecessary couplings and crosstalk. Implementing the full wave analysis on the CBCPW structure, we can discover that the leaky wave propagates along a particular angle relative to the main CPW line, causing the wave to propagate as if in a parallel plate waveguide (PPW). Therefore, we can etch rectangular slots along the ground planes with the angle we have acquired. If the length of the slot is significantly longer than the width and approximately equals to half the guided wavelength, the slots fed by CBCPW will radiate power efficiently and we can thus obtain a centralized broadside radiation pattern. We then derive a method to improve the aperture efficiency of the antenna by analyzing the equivalent circuit of the slot antenna and also by applying Full Wave Spice, and eventually design a highly efficient antenna with a high main beam gain perpendicular to the array plane. The antenna for direct broadcast from satellites (DBS) is operated at 12 GHz and demands high gain and efficiency, which is also the frequency our antenna operates in, resulting in a radiation pattern with 30.14dBi and a bandwidth of 4.2GHz.
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