volume | PIER Journals

Abstract

This paper presents the design, fabrication, and testing of a compact multiband microstrip patch antenna built on a low-cost FR-4 substrate. The antenna combines a meandered radiating line, a defected ground structure (DGS), and two types of metamaterial resonators - a Square Ring Resonator (SRR) and a Circular Complementary Split Ring Resonator (CCSRR), to achieve multiple operating bands in a small footprint. Full wave simulations in CST Studio Suite predict five resonant bands with reflection coefficient S₁₁ below -10 dB over 2.420-8.216 GHz, with a minimum S₁₁ of -22.24 dB at 3.452 GHz and an overall fractional bandwidth of 108.89 percent. To verify the design, a prototype was fabricated and characterised using a calibrated VNA (Vector Network Analyser). Measurements confirm five resonant bands at 1.871 GHz (S₁₁ = -13.81 dB, 182 MHz bandwidth), 2.573 GHz (-10.10 dB, 52 MHz), 3.704 GHz (-10.27 dB, 65 MHz), 5.095 GHz (-12.11 dB, 676 MHz), and 9.957 GHz (-11.14 dB, 182 MHz). Simulated analysis also indicates stable directivity with a peak realized gain of approximately 2.12 dB at higher operating bands. To accelerate design evaluation, an Artificial Neural Network (ANN) surrogate model was trained on the measured S₁₁ data. The ANN attains a root mean square error of 1.38 dB and a coefficient of determination R² = 0.79, providing near-instantaneous S₁₁ predictions with an approximate 96,500× speedup compared to full-wave electromagnetic simulations. The key contribution of this work is the coordinated use of a meander line for miniaturization, a DGS for bandwidth enhancement, and dual metamaterial loading to realize five distinct operating bands on a single, inexpensive FR-4 board. The proposed antennas operating bands collectively support LTE Band 3, 5G New Radio (NR) sub-6 GHz, IEEE 802.11a/n/acWLAN, and X-band IoT applications.

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Mr. Kanakanala Naga Venkata Khasim

Dr. Boopalan Rajasekar