Small Offset Reflector with Matched Feed for 5G Applications

ABSTRACT

In this paper, the authors propose a two-layer microstrip matched feed for a compact offset reflector with projected diameter equal to 10λ, operating at 3.5 GHz (sub-6 GHz 5G band). The proposed feed consists of a rectangular patch operating in dominant mode at the top layer and a circular patch operating in TM${}_{21}$ mode below it. Both the microstrip patches are excited using two different ports and the excitation ratio between the two ports is varied to obtain the conjugate field matching required for cross-polar suppression in the reflector pattern. The optimum excitation ratio between the two generated modes are obtained through a parametric study for three different F/D (focal length to diameter) values of 0.4, 0.6 and 0.8. The proposed matched feed is a low cost feed designed on FR4 substrate and its pattern is obtained using HFSS and CST. The reflector pattern of the offset reflector is calculated using geometrical optics technique and verified in HFSS-PO. The cross-polarization in the reflector pattern obtained using both the geometrical optics and HFSS-PO are better than $-40$ dB for an offset reflector with $F/D=0.6$. The characteristics of the proposed matched feed are verified by comparing the simulation and the measured results of a fabricated prototype.

KEYWORDS:

• Offset reflector
• 5G sub-6 GHz band
• Microstrip antenna
• Matched feed
• Cross-polarization

Disclosure statement

No potential conflict of interest was reported by the author(s).

Additional information

Notes on contributors

Kaushik Debbarma

Kaushik Debbarma received his BE in electronics and telecommunication engineering from University of Pune in 2011 and his MTech (Communication Engineering) from NIT Agartala in 2014. He is currently pursuing his PhD degree from Department of Electronics and Electrical Engineering, IIT Guwahati, Guwahati, India. He is also a recipient of National Talent Search Award in given by NCERT (National Council of Educational Research and Training), India in 2006. His current research interests include matched feed designs for reflector antennas, microstrip antenna designs, RF circuit designs and antenna array designs.

Ratnajit Bhattacharjee

Ratnajit Bhattacharjee received his BE in electronics and telecommunication engineering (First Class Hons) from Guwahati University (Institute: REC (at present NIT) Silchar), MTech (E and ECE Department, Microwave Engineering specialization) from IIT Kharagpur and PhD (Engineering) from Jadavpur University, Kolkata. Presently, he is a professor in the Department of Electronics and Electrical Engineering, IIT Guwahati. Prior to joining IIT Guwahati in 2002, he was a faculty member in REC (NIT) Silchar. His research interests include wireless communication, wireless networks, microstrip antennas, microwave engineering and electromagnetics. Thirteen research students have completed their PhD under his supervision and at present several students are working under his guidance. He has co-authored about one hundred and fifty research papers in journals, international and national conferences. He has served as General Chair for 5th edition of IEEE Applied Electromagnetic Conference, AEMC 2015 and 22nd National Conference on Communications, NCC 2016, Chairman for the NPSC 2014 and Convener for IESC 2017. He has delivered invited talks in several conferences, workshops and symposia. He has also served as TPC member for several conferences. He has developed a web course on Electromagnetic Theory and a MOOC Video course on Microwave Engineering under the NPTEL project of MHRD, India and also involved with the on-going mission project on Virtual Labs as coordinator of EE discipline laboratories and Institute coordinator for IIT Guwahati. He was a Co-investigator for the contracted research from NICT Japan in the area of next-generation wireless networks and PI for a project from ISRO, India in the area of development of matched feed for offset reflector antennas. Currently, he is chief investigator for a Ministry of Electronics and Information Technology (MeitY) India sponsored project for setting up of an Electronics & ICT Academy at IIT Guwahati. He is a member of IEEE and life member of Indian Society of Technical Education. Email: [email protected]