Design of Branch Line Coupler based on Ridge Gap Waveguide Technology for X-band Application

Abstract

This paper describes a branch line coupler designed based on the Ridge Gap Waveguide for X-band application. Ridge Gap Waveguide (RGW) technology has been recently noticed as an alternative to hollow waveguides, particularly for high frequencies such as millimeter waves. This new type of gap waveguide is formed between two parallel metal plates which are separated by an air gap less than a quarter wavelength. One of the plates is a perfect magnetic conductor (PMC) to create a high impedance surface and the other a perfect electric conductor (PEC) on top of it. There is no need for electrical contact between them what makes the construction simpler. These new waveguides are completely enclosed by periodic pins structure without the presence of cavity modes and have lower losses than microstrip lines. The prototype 3dB coupler has been simulated and fabricated to operate at 11 GHz. Measurement results confirm simulations and demonstrate about 13% of bandwidth (|S₁₁| < −10 dB) covering the frequency range of 10.36–11.77 GHz.

KEYWORDS:

• 3dB Coupler
• Millimeter wave
• Parallel-plate waveguide
• Ridge gap waveguide

Additional information

Notes on contributors

Mahboubeh Taraji

Mahboubeh Taraji was born in Noshahr, Iran, in 1988. She received her BSc degree in telecommunication engineering from the University of Zanjan, Zanjan, Iran, in 2012. Also, she received her MSc degree in telecommunication engineering from Science and Research Branch of Islamic Azad University, Tehran, Iran, in 2016. Her research interests include millimeter and sub-millimeter wave applications, gap waveguide technology, passive components, and planar array antennas design. Email: [email protected]

Mohammad Naser-Moghaddasi

Mohammad Naser-Moghaddasi was born in Saveh, Iran, in 1959. He received the BSc degree in communication engineering in 1985 from the Leeds Becket University (formerly Leeds Polytechnic), UK. Between 1985 and 1987 he worked as an RF design engineer for the Gigatech Company in Newcastle Upon Tyne, UK. From 1987 to 1989, he was awarded a full scholarship by the Leeds educational authority to pursue an MPhil studying in CAD of Microwave Circuits. He received his PhD in 1993, from the University of Bradford, UK. He was offered then a two years post doc. to pursue research on microwave cooking of materials at the University of Nottingham, UK. From 1995, Dr Naser-Moghaddasi joined Islamic Azad University, Science & Research Branch, Tehran, Iran, where he currently is a full professor and head of department. His main areas of interest in research are microstrip antenna, microwave passive and active circuits, RF MEMS and electromagnetic compatibility. Dr Naser-Moghaddasi is a member of the Institution of Engineering and Technology, MIET and the Institute of Electronics, Information and Communication Engineers (IEICE). He has so far published over 200 papers in different journals and conferences.