PERFORMANCE ENHANCEMENT OF CIRCULARLY POLARIZED MICROSTRIP ANTENNA USING SINGLE-LAYER FOAM SUBSTRATE FOR 5.8 GHZ ISM BAND APPLICATIONS

Since last decade, a microstrip patch antenna has played a very important role in industrial, scientific, and medical (ISM) band applications, but single-layer antennae suffer from low gain and low radiation efficiency. For an ISM band, there is always a trade-off between these parameters, so maintaining it on a single-layer microstrip antenna is a big challenge. A circularly polarized (CP) microstrip antenna using a single-layer foam substrate has been designed for 5.8 GHz ISM band which offers high gain, improved radiation efficiency, and a lightweight design. It is constructed as a low-profile, single coaxial feed microstrip antenna on a foam substrate, achieving circular polarization by integrating two slots into the radiating patch antenna has dimensions of 0.98 λ<sub>0</sub> × 0.98 λ<sub>0</sub> × 0.096 λ<sub>0</sub>, impedance bandwidth of 600 MHz (5.56-6.16) GHz, which underscores its adaptability across a wide range of frequencies within the specified band. Furthermore, it elaborates the axial ratio bandwidth which extends over 130 MHz (5.77-5.90) GHz, showing the antenna's ability to maintain circular polarization characteristics over a significant frequency range with a gain of 8.87 dB. The experimental and simulation results confirmed a remarkable radiation efficiency of 95.62%, showing its superior effectiveness compared to any existing single-layer microstrip antenna.