Compact Multiband Meander-Line Microstrip Metamaterial Antenna with DGS and AI-Assisted Surrogate Analysis
Kanakanala Naga Venkata Khasim and
Boopalan Rajasekar
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.
