Design and Performance of a Slot-Loaded Reconfigurable Antenna with PIN Diode for Wireless Communication

With the rapid expansion of wireless communication systems, frequency agility has become essential. This paper presents a compact frequency-tunable slot antenna operating in the 4 to 8 GHz range, designed for modern applications. The antenna features a modified rectangular slot with four circular structures and a PIN diode, enabling two modes: Mode 1 (diode off) at 5.27 GHz and Mode 2 (diode on) covering 5.05 GHz and 7.6 GHz. Fabricated on Rogers RT Duroid 5880 substrate, the design offers low loss, high efficiency, and wide impedance bandwidth. Simulations using CST Studio Suite show excellent performance, including effective return loss, good impedance matching, and peak gains of 6.4 dBi. The PIN diode enables frequency reconfigurability, significantly improving the reflection coefficient to -48.71 dB at 5.272 GHz. The antenna achieves directivity gains of 4.7 dBi, 6.4 dBi, and 4.3 dBi at the respective frequencies, ensuring high radiation efficiency in both diode states. This reconfigurable antenna provides a cost-effective, versatile solution for 5G, IoT, and cognitive radio networks, offering frequency flexibility and efficient performance, eliminating the need for multiple antennas.