A Novel Design Method of C‐Shaped Slots for Reconfigurable Band‐Notched UWB Antenna

A novel design method of C‐shaped slots with adjustable effective lengths to achieve reconfigurable band notches in ultra‐wideband antennas is proposed in this paper. Its novelty lies in using C‐shaped slots to design specific band notches and electrical switches to enable performance reconfiguration. Specifically, the lengths of the C‐shaped slots corresponding to the desired band notches are first established, and then PIN diodes are placed at the appropriate locations to connect the C‐shaped slots at the same end, thereby overlapping them. Controlling the ON/OFF state combinations of PIN diodes can adjust the effective lengths of these C‐shaped slots. As a design example, two PIN diodes are incorporated into a circular patch antenna to form three C‐shaped slots with different effective lengths. Simulation results show that by changing these PIN diode state combinations, the proposed antenna can reconfigure between UWB (2.89–15 GHz) and three specific single‐band notches: the S‐band (2.74–3.36 GHz), the WiMAX band (3.45–3.97 GHz), and the C‐band (4.47–4.98 GHz). Throughout the entire operating band, it can also sustain favorable radiation patterns (“8”‐shaped in the E‐plane and omnidirectional in the H‐plane) and steady gain (up to 4.8 dB). The measured results of its prototype agree well with the simulated ones. Furthermore, the band‐notched mechanism reveals that various ON/OFF state combinations change the effective lengths of the C‐shaped slots and reverse the direction of surface currents on both sides of these slots, thereby suppressing electromagnetic wave radiation.