Mushroom Unit Cell Loaded Triple Band Microstrip Antenna for Sub-6 GHz MIMO and Phased Array Application

In this paper, a mushroom unit-cell loaded mult-iband microstrip antenna sub-array is proposed. Here, the mushroom unit-cell surrounded with a square slot is etched out at the diagonal corner of the square patch antenna to achieve multi-band response (3.21 GHz, 3.42 GHz, 3.68 GHz) at sub-6 GHz frequency band. The proposed technique achieves antenna miniaturization yielding a footprint of 0.19λ0 × 0.19λ0, where λ0 is the free space wavelength at 3. 21 GHz. Next, the proposed antenna is used to con figure 2 × 2 sub-array for MIMO / phased array applications. The proposed sub-array achieves satisfactory impedance matching of ≤ −15 dB, interport isolation of ≤ 25 dB, better SLL of ≤ −20 dB, maximum sub-array gain of 7.6 dBi, and 3 dB beam width of 59⁰. Further, the proposed 2 × 2 sub-array demonstrates beam steering up to 80⁰. The proposed sub-array is fabricated and validated by s-parameter measurement.