Dual-Port Filtenna System for Interweave Cognitive Radio Applications

Abstract

This work presents a compact, low-cost dual-port filtenna system for interweave cognitive radio (CR) applications. The filtenna system consists of a frequency-bandwidth reconfigurable narrowband filtenna (RNF) and a wideband filtenna (WF) with a sharp rejection in the stopband of both filtenna systems. The RNF switches between two narrow bands (3.36–3.81) GHz with a center frequency of 3.506 GHz and (4.88–5.76) GHz with a center frequency of 5.235 GHz, including the WiMAX, 5G, and WLAN bands. A pair of PIN diodes are used to switch between the two bands of the RNF. The operating frequency of the WF covers the range of 3.12–6.025 GHz, which is sufficient to cover the two bands of the RNF. The RNF consists of a half-elliptical-shaped patch antenna with a triangle cap augmented with a reconfigurable E-shaped BPF, while the WF consists of a wideband filter integrated onto the transmission feed line of the half-elliptical-shaped monopole antenna. The proposed filters result in a flat response in the passband with two sharp transmission zeros at the stopband. The overall electrical size of the filtenna system is $0.364{{\lambda }}_{\mathrm{L}}\times {0.5408} {{\lambda }}_{\mathrm{L}}$ where ${{\lambda }}_{\mathrm{L}}$ is the wavelength at the lower cutoff frequency of the entire − 10 dB operating frequency range. The measurements agree well with the simulations, and they show an omnidirectional power pattern for both RNF and WF, which is suitable for interwave CR applications.