Defected Ground Structure Integrated Rectangular Microstrip Patch Antenna on Semi-insulating Substrate for Improved Pola

A simple rectangular microstrip antenna with defected ground structure on semi-insulating substrate (GaAs) has been studied to improve the polarization purity (co-polarization to cross-polarization isolation) in principle H-plane. Wide bandgap with high d

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Abstract A simple rectangular microstrip antenna with defected ground structure on semi-insulating substrate (GaAs) has been studied to improve the polarization purity (co-polarization to cross-polarization isolation) in principle H-plane. Wide bandgap with high dielectric constant makes GaAs a very good substrate for Monolithic Microwave Integrated Circuits (MMIC). Unlike the earlier reports, the present one can exhibit much better radiation performance with the simple configuration. In the present paper, initially the effect of dielectric constant of a substrate on radiation performance of a simple conventional patch configuration has been studied and documented. Based on the investigation, defected ground structure has been employed for obtaining much better radiation characteristics. Around 69% improvement in cross-polarization isolation is revealed from the present configuration compared to classical patch antenna. Furthermore, such improvement of polarization purity is maintained over a wide elevation angle. Along with the improvement in polarization purity, the present structure also reveals a broad and stable beam pattern at its design frequency. Keywords Microstrip antenna arsenide Polarization purity



 Defected ground structure (DGS)  Gallium

1 Introduction Rectangular microstrip patch antenna (RMA) is the most common and suitable microwave radiator that find potential applications in modern wireless systems due to its several advantages like lightweight, tininess, and easy fabrication process. A. Ghosh (&) Department of ECE, Mizoram University, 796004 Aizawl, Mizoram, India e-mail: [email protected] B. Basu Department of ECE, National Institute of Technology-Silchar, 788010 Silchar, Assam, India © Springer Nature Singapore Pte Ltd. 2019 A. K. Luhach et al. (eds.), Smart Computational Strategies: Theoretical and Practical Aspects, https://doi.org/10.1007/978-981-13-6295-8_15

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Apart from all these advantages, conventional RMA suffers low gain, narrow bandwidth, and poor co-polarization to cross-polarization isolation [1, 2]. Conventional RMA radiates some degree of cross-polarization (XP) radiation in its higher order orthogonal mode, while radiating linearly polarized (Co-polarization (CP)) electrical fields along the broadside direction in its fundamental TM10 mode. The cross-polarized (XP) radiation from first higher order orthogonal mode (i.e., TM02) is much severe and affects the performance of conventional RMA in some applications where polarization purity is the primary requirement [3]. In probe-feed design of RMA, the XP is more prominent when the thickness increases as well as the dielectric constant of the substrate decreases [4]. Thus, achieving high CP-XP isolation (polarization purity) becomes a challenging topic for antenna research community. Different techniques like modification of feed structure, aperture-coupled dual polarization have been reported to improve the polarization purity of RMA. Cross-polarization level below −20 dB in both planes

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