A Unidirectional, Printed Antenna With High Interport Isolation Over Wider Bandwidth for 2.4 GHz Full Duplex Applications
Haq Nawaz, Noman Ahmad, Javaria Aslam
Abstract
This work presents a dual-polarized, proximity-fed bistatic antenna system with comparatively wideband self-interference cancellation (SIC) performance for 2.4 GHz single-channel full-duplex (SCFD) or in-band full-duplex (IBFD) wireless applications. The presented antenna system is comprised of two closely spaced (spatial separation of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{\mathrm {o}}$ </tex-math></inline-formula> /4) proximity-fed patches with dual-polarized characteristics for transmit (T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> ) and receive (R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> ) modes. The proximity feeding offers comparatively wider impedance bandwidths (BWs) for both T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> and R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> ports. The T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> mode is excited through a single-port proximity-fed square patch, whereas the R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> mode operation is realized through a differentially driven proximity-fed dual-port patch. The compact structure for the presented antenna is realized through the vias interconnection of R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> ports of patch and differential feeding circuit. The implemented antenna prototype characterizes better than 87 dB peak interport decoupling, and the experimental results demonstrate higher than 80 dB interport isolation over the entire 10 dB return-loss impedance BW of 120 MHz for the presented antenna. Furthermore, the recorded results provide better than 6 dBi gains with higher than 75% peak radiation efficiencies for both T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> and R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> modes. In addition, the measured cross-polarization levels are more than 30 and 42 dB below the respective T <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> and R <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">x</sub> co-polarization levels. The contributions of this work are the demonstration of a compact, dual-port antenna with comparatively wider impedance and isolation BWs along with low cross-polarization characteristics for both modes without compromising the radiation performance and electrical size of the proximity-fed printed patch antenna.