Design and Fabrication of a Miniaturized Reconfigurable Antenna Based on a PIN Diode for IoT Applications

Abstract

This paper describes a frequency-reconfigurable antenna that uses PIN diodes and a biasing circuit integrated into the same substrate. Designing compact frequency-reconfigurable antennas with stable multiband performance remains an important challenge for modern wireless and IoT applications. The proposed antenna is small and flexible, enabling operation over multiple frequency bands and modes. The antenna is 26×14×1.524 mm³ in size and printed on a Rogers 4350 substrate (εr = 3.66, tan δ = 0.0037). Two PIN diodes are used to change the operating frequency. The antenna operates in four switching states and covers seven different frequency bands. The first mode is single-band (3.88 GHz), the second is dual-band (3.4 GHz, 4.9 GHz), the third is tri-band (3.5 GHz, 5.3 GHz, 6.8 GHz), and the fourth is dual-band (3.4 GHz, 6.7 GHz). The antenna has a simulated radiation efficiency of about 94% and a peak gain of 2.7 dBi. The simulated results are in good agreement with the experimental measurements, showing close agreement. The main contribution of this work is achieving seven operating bands using only two PIN diodes while maintaining a compact antenna size. The suggested antenna works well for small wireless and IoT applications.