Compact CPW‐fed half‐ring‐shaped slot antenna for harmonic suppression applications

Abstract

ABSTRACT A compact half‐ring‐shaped (HRS) slot antenna fed by a coplanar waveguide (CPW) transmission line for harmonic suppression applications is presented. The antenna consists of an HRS slot and stepped impedance resonators (SIRs) symmetrically appended to the slot at both ends. Two SIRs are used to suppress the harmonics of the fundamental resonance frequency with an additional effect of size reduction. The optimized HRS slot antenna with SIRs operating at 2.45 GHz is fabricated on an FR4 substrate with dimensions of 30 mm by 30 mm, and its performance is compared to that of a conventional rectangular slot antenna. The slot length of the proposed harmonic‐suppressed slot antenna is reduced by 45% compared to a conventional rectangular slot antenna owing to the HRS slot and appended SIRs. Experiment results show that the proposed antenna has the desired impedance characteristic with a frequency band of 2.39–2.49 GHz for a voltage standing wave (VSWR) < 2, and a measured gain of 1.5 dBi at 2.45 GHz. In addition, the suppression of the second, third, and fourth harmonics are successfully demonstrated. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1102–1104, 2015