Study on Extremely Compact Triple Band-Rejected Antenna in Indoor Propagation Channel for IR UWB and Biomedical Applications

This communication investigates the frequency- and time-domain features of an extremely compact super-wideband slot antenna designed for impulse radio (IR) ultrawideband (UWB) and biomedical applications. The antenna employs a circular radiation patch and a rectangular slot in the ground plane, with optimized dimensions to achieve super-wide bandwidth. To address interference issues with co-existing narrowband systems, two inverse L-shaped stubs are connected to the ground plane, effectively rejecting the WiMAX spectrum. In addition, two circle-like ring slots are embedded into the radiation patch to create band-rejected features for WLAN and X-band downlink frequencies. Despite its compact size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$14\times 14$ </tex-math></inline-formula> mm (<inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.13\lambda _{\text {g}} \times 0.13\lambda _{\text {g}}$ </tex-math></inline-formula>), the antenna offers a bandwidth extending from 2.8 to over 20 GHz, making it suitable for UWB (3.1–10.6 GHz) and Ku-band (12–18 GHz) applications. This communication also explores the antenna’s impact on transmitting and receiving ultranarrow pulses for IR biomedical applications, assessed using the system fidelity factor (SFF). A noteworthy contribution of this work is the investigation of the time-domain properties of the proposed antenna in a typical indoor propagation channel. The simulated and measured results demonstrate the antenna’s favorable characteristics in both the frequency and time domains.