B. Zakeri, H. Bernety,
Volume 10, Issue 4 (12-2014)
Abstract
Band-notch characteristic has been of great interest recently to overcome the electromagnetic interference of Ultra-wideband systems (UWB) with other existing ones. In this paper, we present a novel microstrip-fed antenna with band rejection property appropriate for UWB applications. Band-notch characteristic has been achieved by adding a rectangular resonant element to the ground section. A prototype was fabricated and measured based upon optimal parameters. Experimental results show consistency with simulation results. Measurement results confirm that the antenna covers the UWB band and satisfies a band rejection in the frequency span of 5 GHz to 5.7 GHz to restrain it from interference with Wireless Local Area Network (WLAN). Then, to achieve better isolation, a rectangular strip is appended to the band-notch creating part of the ground section to enhance obtained VSWR up to 30 through simulation. In addition, by applying a similar technique, a dual band-notched characteristic with an average simulated VSWR of around 13.75 has been achieved for WLAN and the downlink of X band satellite communication systems with each more than 10. Features such as small size, omnidirectional pattern and perfect isolation make the antenna suitable for any UWB applications.
Omar S Abdulwahid, Saad G Muttlak, James Sexton, Michael J Kelly, Mohamed Missous,
Volume 21, Issue 4 (11-2025)
Abstract
An analysis of 6×6 µm2 GaAs/AlAs Asymmetric Spacer Layer Tunnel diode has been conducted to evaluate the DC and RF characteristics at different bias conditions. At zero voltage operation, the diode exhibited a measured curvature coefficient of 22 V-1, corresponding to a junction resistance of 27 kΩ. The measured and simulated S11 reflection coefficient of the integrated detector including the diode, matching circuit, and output capacitance achieved to be less than -10 dB at the desired frequency. The extracted low series resistance and junction capacitance of the tunnel diode resulted a high voltage sensitivity of 3650 V/W and low noise equivalent power of 5.5 pW/
at 11 GHz resonant frequency and -27 dBm input power. The developed detector model can be extended to implement RF detectors operating at frequencies reaching mm-wave regime applications. This is with consideration of the requirements for sub-micrometer scale mesa devices, eliminating the effects of associated parasitic elements and improved matching network performance.
