Wideband Printed Ridge Gap Rat-Race Coupler for Differential Feeding Antenna

In this paper, a wideband 3 dB hybrid 180° rat-race coupler is introduced in the printed ridge gap waveguide technology. It has simultaneous wide matching and isolation bandwidth with low output amplitude imbalance. It operates in the millimeter wave band from 25.8 to 34.2 GHz (27.96%) with 15 dB return loss and isolation, and ±0.5 dB output amplitude imbalance. The proposed design employing an open stub at the middle of the $3 \lambda /4$ branch line and quarter wavelength lines at all the ports of the coupler. The objective of the added open stub is to separate the output ports amplitudes around the -3 dB level by certain values depending on the required amplitude imbalance. The analytical derivation for the role of the added open stub is presented along with a parametric study on its effect on amplitude imbalance, matching, and isolation. This results in having two intersection points for the output ports instead of one of the conventional coupler and hence the amplitude imbalance bandwidth increases. The objective of the added quarter wavelength lines is to improve the matching and isolation bandwidths. First, the conventional rat-race coupler is presented and a bandwidth of 14.25% at 30 GHz is achieved. After that the rat-race with the added quarter wavelength lines is presented to illustrate the objective of the added quarter wavelength lines and a bandwidth of 19.44% is achieved. Finally, the rat-race with the quarter wavelength lines and the added stub is presented and a prototype is fabricated and measured. The s-parameters measurements are in a good agreement with the simulated ones.

[2]  A. Sebak,et al.  Analysis and design of a 30 GHz printed ridge gap Ring-crossover , 2019, 2019 USNC-URSI Radio Science Meeting (Joint with AP-S Symposium).

[3]  A. Kishk,et al.  Efficient Procedure to Design Large Finite Array and Its Feeding Network With Examples of ME-Dipole Array and Microstrip Ridge Gap Waveguide Feed , 2020, IEEE Transactions on Antennas and Propagation.

[4]  Bill Slade,et al.  Reduced-size octave-bandwidth microstrip / lumped-element rat-race coupler , 2010 .

[5]  Chu-Chen Yang,et al.  A novel broad-band Chebyshev-response rat-race ring coupler , 1999 .

[6]  Mohamed Ali,et al.  Analysis and Design of a Wideband Coaxial Transition to Metal and Printed Ridge Gap Waveguide , 2018, IEEE Access.

[7]  Per-Simon Kildal,et al.  Three metamaterial-based gap waveguides between parallel metal plates for mm/submm waves , 2009, 2009 3rd European Conference on Antennas and Propagation.

[8]  Hojatollah Zamani,et al.  1.5-D Sparse Array for Millimeter-Wave Imaging Based on Compressive Sensing Techniques , 2018, IEEE Transactions on Antennas and Propagation.

[9]  H. Aubert,et al.  Miniaturized Hybrid Ring Coupler Using Electromagnetic Bandgap Loaded Ridge Substrate Integrated Waveguide , 2011, IEEE Microwave and Wireless Components Letters.

[10]  A. Sebak,et al.  2-D Scanning Magnetoelectric Dipole Antenna Array Fed by RGW Butler Matrix , 2018, IEEE Transactions on Antennas and Propagation.

[11]  S. Koziel,et al.  On elementary cell selection for miniaturized microstrip rat-race coupler design , 2017, 2017 International Conference on Electromagnetics in Advanced Applications (ICEAA).

[12]  Abdel-Razik Sebak,et al.  $4\times4$ -Element Cavity Slot Antenna Differentially-Fed by Odd Mode Ridge Gap Waveguide , 2019, IEEE Access.

[13]  Abdel-Razik Sebak,et al.  Printed Ridge Gap Waveguide 3-dB Coupler: Analysis and Design Procedure , 2018, IEEE Access.

[14]  Chi-Yang Chang,et al.  A compact wideband 1800 hybrid ring coupler using a novel interdigital CPS inverter , 2007, 2007 European Microwave Conference.

[15]  Dong Il Kim,et al.  Broad-Band Design of Improved Hybrid-Ring 3-dB Directional Couplers , 1982 .

[16]  M. Naser‐Moghadasi,et al.  Efficient and Accurate Analysis of a Substrate Integrated Waveguide (SIW) Rat-Race Coupler Excited by Four U-Shape Slot- Coupled Transitions , 2015 .

[17]  P. Kapitanova,et al.  180° Power Dividers Using Metamaterial Transmission Lines , 2008, 2008 14th Conference on Microwave Techniques.

[18]  Jian Yang,et al.  Empirical Formulas For Designing Gap‐Waveguide Hybrid Ring Coupler , 2013 .

[19]  Jian Yang,et al.  Microstrip-Ridge Gap Waveguide–Study of Losses, Bends, and Transition to WR-15 , 2014, IEEE Transactions on Microwave Theory and Techniques.

[20]  Chun Hsiung Chen,et al.  Novel uniplanar 180/spl deg/ hybrid-ring couplers with spiral-type phase inverters , 2000 .

[21]  Justin L. Fernandes,et al.  Wide-bandwidth, wide-beamwidth, high-resolution, millimeter-wave imaging for concealed weapon detection , 2013, Defense, Security, and Sensing.

[22]  Ke Wu,et al.  H‐plane 3‐dB hybrid ring of high isolation in substrate‐integrated rectangular waveguide (SIRW) , 2006 .

[23]  S. Birgermajer,et al.  Microstrip-Ridge Gap Waveguide Filter Based on Cavity Resonators With Mushroom Inclusions , 2018, IEEE Transactions on Microwave Theory and Techniques.

[24]  A novel reduced-size 60-GHz 180° coupler using LG-CPW transmission lines , 2011, Asia-Pacific Microwave Conference 2011.

[25]  Ke Wu,et al.  Miniaturized hybrid ring circuits using T-type folded substrate integrated waveguide (TFSIW) , 2009, 2009 IEEE MTT-S International Microwave Symposium Digest.

[26]  Yeong-Her Wang,et al.  Design of Compact 90 $^{\circ}$ and 180 $^{\circ}$ Couplers With Harmonic Suppression Using Lumped-Element Bandstop Resonators , 2010, IEEE Transactions on Microwave Theory and Techniques.

[27]  P.-S. Kildal,et al.  Design of transition from coaxial line to ridge gap waveguide , 2009, 2009 IEEE Antennas and Propagation Society International Symposium.

[28]  Krzysztof Wincza,et al.  Bandwidth improvement of rat-race couplers having left-handed transmission-line sections , 2014 .

[29]  S. March.  A Wideband Stripline Hybrid Ring (Correspondence) , 1968 .

[30]  A. Sebak,et al.  Millimeter-wave imaging system using a 60 GHz dual-polarized AFTSA-SC probe , 2016, 2016 33rd National Radio Science Conference (NRSC).

[31]  Abdel-Razik Sebak,et al.  Analytical Design Procedure for Forward Wave Couplers in RGW Technology Based on Hybrid PEC/PMC Waveguide Model , 2019, IEEE Access.

[32]  Chang-Ze Li,et al.  Wideband Hybrid Ring Coupler Based on Half-Mode Substrate Integrated Waveguide , 2014, IEEE Microwave and Wireless Components Letters.

[34]  Thomas E. Hall,et al.  Three-dimensional millimeter-wave imaging for concealed weapon detection , 2001 .

[35]  Eva Rajo-Iglesias,et al.  Design and experimental verification of ridge gap waveguide in bed of nails for parallel-plate mode suppression , 2011 .

[36]  Langis Roy,et al.  Miniaturized 180$^{\circ}$ Hybrid Coupler in LTCC for L-Band Applications , 2014, IEEE Microwave and Wireless Components Letters.

[37]  Kanaparthi V. Phani Kumar,et al.  Design of compact 180° hybrid coupler for unequal power division ratio using slow wave structures , 2017, 2017 Twenty-third National Conference on Communications (NCC).

[38]  Abdel-Razik Sebak,et al.  High Gain Bow-Tie Slot Antenna Array Loaded With Grooves Based on Printed Ridge Gap Waveguide Technology , 2019, IEEE Access.

[39]  Kian Sen Ang,et al.  A new class of multisection 180/spl deg/ hybrids based on cascadable hybrid-ring couplers , 2002 .