Compact filtering antenna using asymmetric CPW-fed based CRLH structure

Abstract

Compact filtering antenna using composite right/ left-handed (CRLH) transmission line structure is presented in this paper. It utilizes a simplified asymmetric coplanar waveguide (CPW) feeding method. Initially, a bandpass filter has been designed with a circular interdigital capacitor, meander line and rectangular patches with asymmetric CPW feeding. The filtering antenna structure has been designed by replacing the rectangular patch and coupling at load side (Port-2) of the designed filter with L-shaped patch, which acts as a radiating element. The resonance frequency can be controlled by the series parameter due to shorted boundary condition of the structure. The designed filtering antenna resonates at 3.4 GHz with 10-dB impedance bandwidth of 23.5%. It provides a nearly flat gain response within the passband by the average value of 2.5 dB along with two radiation null at 2.1 GHz and 4.5 GHz. The total size of the designed structure is 0.39λg × 0.26λg at the resonance frequency (3.4 GHz) of the working band. It gives an omnidirectional radiation pattern at the resonance frequency. The designed prototype is fabricated and measurements are done for validation of simulated results and the filtering antenna is made useful for sub-6 GHz of 5G (3.3–3.6 GHz) applications.