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Research Article |

Suppression of Reflector-Induced Resonance Detuning in a Compact Microstrip Antenna Using Offset Reflector Placement

Author(s): Narmin H.AL-Zahawi1, Haveen Yaseen Hussein AL-Zahawi2*, Saja Mazin Sami3, Zainab S.Husamuldeen4

Published In : International Journal of Electrical and Electronics Research (IJEER)        Volume 14, Issue 3

Publisher : FOREX Publication

Published : 30 September 2026

e-ISSN : 2347-470X

Page(s) : 716-726

DOI: https://doi.org/10.37391/IJEER.140306

Abstract

The impact of reflector symmetry on the frequency stability of the proposed antenna, which employs three elliptical radiating elements printed on a Rogers RT/Duroid 5880 substrate (30 × 30 mm²) and operates around 5.7 GHz, is investigated using different reflector configurations. Full-wave simulations show that a centrally located metallic reflector increases the realized gain from 2.4 to 8.1 dBi; however, the operating resonance shifts downward by approximately 1 GHz, from 5.7 to 4.7 GHz, due to strong symmetric coupling between the antenna current and the image current on the reflector. To mitigate this resonance detuning, an offset-reflector configuration is introduced to provide controlled asymmetric coupling. The simulated offset-reflector configuration preserves operation near 5.7 GHz while providing a realized gain of approximately 3.23 dBi and a radiation efficiency of 94%. Experimental S11 measurements of the unloaded, centered-reflector, and offset-reflector configurations confirm the predicted resonance-detuning and resonance-stabilization trends. Parametric studies are additionally conducted to examine the effects of the elliptical dimensions and substrate thickness on impedance behavior and resonance alignment. The results demonstrate that controlled reflector asymmetry provides a simple, low-complexity strategy for balancing directional enhancement and resonance stability without requiring meta-surfaces, multilayered structures, or other parasitic elements.

Keywords: Compact Microstrip Antenna, Offset Reflector, Resonance Stability, Reflector-Induced Coupling, Directional Radiation Enhancement, Surface Current Distribution, Single-Band Antenna, Impedance Matching.




Narmin H.AL-Zahawi, Department of Communication Engineering, University of Diyala, Diyala, Iraq; Email: n.mirza@uodiyala.edu.iq

Haveen Yaseen Hussein AL-Zahawi, Department of Communication Engineering, University of Diyala, Diyala, Iraq; Email: : haveeny.al_zahawi@uodiyala.edu.iq

Saja Mazin Sami, Department of Electrical power and Machines Engineering, University of Diyala, Diyala, Iraq; Email: s.m.sami@uodiyala.edu.iq

Zainab S. Husamuldeen, Department of communication Engineering, University of Diyala, Iraq; Email: zainab.salah.eng.comm.@uodiyala.edu.iq

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Narmin H.AL-Zahawi, Haveen Yaseen Hussein AL-Zahawi, Saja Mazin Sami, and Zainab S. Husamuldeen (2026), Suppression of Reflector-Induced Resonance Detuning in a Compact Microstrip Antenna Using Offset Reflector Placement. IJEER 14(3), 716-726. DOI: 10.37391/IJEER.140306.