Circularly Polarized MIMO Antenna With Asymmetries in Circular Patch for mmWave Applications

Abstract

At high frequency, linearly polarized antennas are not good choices for long distance communication because of wave polarization. Circularly polarized antennas are perfect choice to overcome the mismatch or wave polarization at high frequencies. Variety of planar antennas have been reported in last two decades for the millimeter wave applications. Due to high metal and dielectric losses, most of the 4G laminates are limited in use for 5G trans-receive operations. In this research, a compact circularly polarized multiple input multiple output (MIMO) antenna with asymmetries in circular patch is designed for 5G mmWave band. The MIMO antenna with multiple sectoral slots at different angles and half-moon shaped slot is designed on Rogers 5880 substrate of size $5.98\lambda \times 2.99\lambda \times 0.07\lambda$. The proposed antenna covers the 2:1 VSWR frequency band of 25.45–32.92 GHz and axial ratio band of 26.24–29.88 GHz. The operating bandwidth is 7.47 GHz, and the axial ratio bandwidth is 3.64 GHz. The presented design achieves gain of more than 5.8 dBi and more than 91.72% radiation efficiency in band. The maximum value of the gain in band is 6.68 dBi. The ECC is in the range of 10⁻² in the whole operating band, and MEG in the design is less than −3 dB for XPR = 0 dB for both the isotropic and Gaussian environments and also less than −3 dB for XPR = 6 dB for Gaussian environment.