Compact ACS‐fed frequency reconfigurable octa‐band antenna for wireless portable systems

Abstract In this article, the design and analysis of a compact octa‐band antenna employing the PIN diode to realize frequency reconfigurable characteristics is presented. The presented antenna is backed by a partial ground plane and printed on top of a 1.53 mm thicker FR4 substrate. The antenna size is very compact (25 mm × 14 mm × 1.53 mm), and can be readily incorporated with many other RF front‐end circuits. The presented antenna consists of a semi‐heptagonal, semi‐hexagonal, inverted L‐shaped, and inverted Z‐shaped monopoles. Depending on the position of the lumped element switch, the presented antenna can operate in eight different frequency modes. The investigated antenna realizes Penta/Triple band characteristics by turning ON/OFF the PIN diode positioned between the inverted L‐shaped monopole and feedline. While in ON state, the investigated antenna covers five unique frequencies 1.82 GHz (DCS/5G NR n70), 2.43 GHz (Bluetooth/RFID), 3.75 GHz (LTE 42–43/5G NR n77/Wi‐MAX), 5.4 GHz (U‐NII‐2A & ‐2B), and 5.84 GHz (U‐NII‐3 & V2X) and in OFF state, the antenna covers three unique frequencies 1.95 GHz (PCS/UMTS/LTE 34–37), 2.59 GHz (LTE 2500 & WLAN 2.4 GHz), 4.71 GHz (5G NR n79 & WLAN 5GHz) for wireless applications. The investigated antenna exhibits excellent impedance bandwidths of 1.69–1.9 GHz (BW = 11.6%), 1.8–2.1 GHz (BW = 15.4%), 2.37–2.56 GHz (BW = 7.7%), 2.4–2.7 GHz (BW = 11.8%), 3.49–4.2 GHz (BW = 18.4%), 4.3–5.55 GHz (BW = 25.4%), 5.2–5.52 GHz (BW = 6%), and 5.78–5.9 GHz (BW = 5.5%) at 1.82/1.95/2.43/2.59/3.75/4.71/5.4, and 5.84 GHz, respectively. The measurements demonstrate that the designed antenna has omnidirectional radiation characteristics with 1.15–4.4 dBi gain. The proposed design's simulated and measured results are compared, and show good agreement.