A Systematic Design of a Compact Wideband Hybrid Directional Coupler Based on Printed RGW Technology

Printed ridge gap waveguide (PRGW) is considered among the state of art guiding technologies due to its low signal distortion and low loss at Millimeter Wave (mmWave) spectrum, which motivates the research community to use this guiding structure as a host technology for various passive microwave and mmWave components. One of the most important passive components used in antenna beam-switching networks is the quadrature hybrid directional coupler providing signal power division with 90° phase shift. A featured design of a broadband and compact PRGW hybrid coupler is propose in this paper. A novel design methodology, based on mode analysis, is introduced to design the objective coupler. The proposed design is suitable for mmWave applications with small electrical dimensions ( 1.2λo×1.2λo ), low loss, and wide bandwidth. The proposed hybrid coupler is fabricated on Roger/RT 6002 substrate material of thickness 0.762 mm. The measured results highlight that the coupler can provide a good return loss with a bandwidth of 26.5% at 30 GHz and isolation beyond 15 dB. The measured phase difference between the coupler output ports is equal 90∘± 5∘ through the interested operating bandwidth. A clear agreement between the simulated and the measured results over the assigned operating bandwidth has been illustrated

Fabrication and Characterization of a W-Band Cylindrical Dielectric Resonator Antenna-Coupled Niobium Microbolometer

We report on the fabrication and characterization of a novel antenna-coupled detector configuration for detection at 94 GHz, a coplanar waveguide- (CPW-) fed, slot-excited twin dielectric resonator antenna- (DRA-) coupled niobium (Nb) microbolometer. The antenna is based on two low permittivity cylindrical dielectric resonators (CDRs) excited by rectangular slots placed below the CDRs. The antenna resonant currents are fed to an Nb microbolometer by the means of a CPW feed. The ceramic DRA structure is manufactured using a novel fabrication process that enables patterning an SU-8–Alumina (Al2O3) nanopowder composite using conventional photolithography. The detector measured a voltage responsivity of 0.181 V/W at a modulation frequency of 150 Hz. The detector measured a time constant of 1.94 μs. The antenna radiation pattern of the developed detector configuration was measured and shows a good agreement with the simulation

A compact ultra wideband bandpass filter using arrow coupled lines with defected ground structure

A new ultra wideband bandpass filter (UWB-BPF) using arrow coupled lines and U-slot defected ground structures (U-DGS) is proposed. The input and output feeding lines are connected to the coupled lines placed on the conductor side of the substrate while the U-slot DGS was etched from the ground side below. The effect of U-DGS slot dimensions on the operating bandpass of the filter was studied. The filter was simulated using both IE3D and HFSS simulators. The simulation results are in good agreement with the realized filter. The filter operating passband extended over the UWB frequency 3.0–9.5 GHz while the group delay variation in the passband is in the range of 0.5°

Design of UWB antenna array for through-wall detection system

In this paper, an ultra-wideband (UWB) antenna array for through-wall microwave imaging (TWMI) system is introduced. The detection system consists of 4-element balanced antipodal Vivaldi antenna array (BAVA) fed by 1-to-4 UWB modified Wilkinson power divider. The antenna element, array, and feed network are optimized, fabricated and tested. The main working principle of the detection system is based on time domain reflectometry (TDR). Wherein, very short pulse generated by the vector network analyzer (VNA) is used to illuminate the wall under investigation through the array system. The exprimental work of scanning a 20 × 20 cm area of two wall separated by 15 cm air gap with the purpose of detecting 4 cm (diameter) metallic ball concealed in a gap between the walls shows a good acuuracy. In order to enhance the resolution of the received image, a special filtering process has been developped and implemented. © 2013 IEEE