Investigations on Dual Band Filtering Antenna for Wireless Applications

Abstract

The paper delineates a unique dual-band filtering antenna that integrates filtering and radiation properties into a single module employing a defective ground structure. The role of a filtering antenna is to remove out-of-band interference from adjacent frequency bands. The proposed configuration consists of a rectangular defective ground structure embedded in the ground plane, along with a filter (designed as a square open loop resonator (SOLR)), and an antenna (designed as an H-shaped radiating element) connected through a coupled line on the substrate's opposite side. The recommended filtenna dimensions are 30 mm × 34 mm × 1.6 mm, functioning at 2.4 GHz and 7.2 GHz. A return loss |S11| < 10 dB occurs at the working frequencies. The H-shaped radiator enables dual-band functionality, and narrowband performance at specified frequencies is achieved by modifying the dimensions of the designed SOLR bandpass filter. Integrating a filter with the antenna element limits the bandwidth to 0.21 GHz, spanning from 2.32 GHz to 2.54 GHz, centered at 2.4 GHz, making it highly suitable for wireless applications. The high-frequency resonance attained at 7.2 GHz (6.46 – 7.56 GHz) is widely employed in short-range radar systems and wireless data communications. Stable gain (> 2 dBi) and radiation patterns are achieved at low and high operating frequencies. The design undergoes simulation, fabrication, and measurement. The validated results strongly correlate, suggesting that the proposed filtering antenna is appropriate for diverse wireless applications.