A compact hybrid reconfigurable antenna using two PIN diodes for C band (4-8 GHZ) applications

This study presents a compact and high-performance hybrid reconfigurable antenna capable of both frequency and radiation pattern reconfiguration using only two PIN diodes integrated with a bias tee circuit. Designed for C-band applications, the antenna occupies a miniaturized footprint of 15 x 23 x 1.6 mm3 and is fabricated on an FR-4 substrate (epsilon r = 4.4, tan delta = 0.02). It consists of a rectangular monopole radiator and two parasitic elements, whose connectivity is controlled through diode switching to achieve dynamic reconfigurability. The antenna supports five distinct resonance frequencies across four switching states ( 00, 01, 10, and 11), covering 4.5 GHz to 7.83 GHz, and enables multiple radiation pattern configurations. These resonance frequencies are at 6.26 GHz( Case 1-00), 5.53 GHz ( Case 2- 01), 4.9 & 7.67 GHz( Case 3-10), and 5 GHz ( Case 4-11), respectively. The integrated bias tee ensures effective RF/DC isolation and low insertion loss, enhancing switching performance and addressing a common limitation in previous designs. Simulated and measured results show strong agreement, with reflection coefficients below -15 dB and peak values reaching -40 dB. The antenna achieves radiation efficiencies between 81% and 92.4% and gain values from 1.93 to 3.61 dBi. Compared to state-of-the-art designs, this antenna offers superior miniaturization, fewer switches, broader reconfigurability, and practical biasing integration, which makes it well-suited for compact, energy-efficient, and adaptive wireless communication systems.