Simultaneous Compensation of Microstrip Feed and Patch by Defected Ground Structure for Reduced Cross-Polarized Radiation

This communication proposes a new idea of compensating spurious radiations usually occurring from the sharp transitions at patch to feed and feed to impedance transformer junctions which result in added cross-polarized (XP) fields in planar microstrip-fed patches. A strategic design and deployment of defected ground structure (DGS) have been explored successfully as a potential means to resolve such long-standing radiation issues. The quantum of radiations from the feed has been theoretically estimated. These along with the main source of XP fields (higher order mode) have been addressed by introducing a composite type of DGS. The experimental validation executed at the C-band establishes this simple low-cost solution with a promise of 10 to 14 dB improvement in the H-plane XP fields. It is also ensured that the proposed technique is equally useful in realizing dual-fed dual-polarized configurations without affecting the primary radiation and antenna performance.

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