A Spiral Cavity Backed 4 X 4 MIMO SIW Antenna at Ku Band for Radio Telescopes
Suryansh Saxena,
Nidhi Tewari and
Shweta Srivastava
A compact spiral cavity backed substrate integrated waveguide (SIW) multiple input multiple output (MIMO) antenna is presented in this paper. The edge-shaped spiral on top of the SIW cavity acts as a dipole antenna. The dual spiral arms are excited from their symmetrical connecting center. The single antenna element in MIMO is rotated such that unit cells are orthogonal to each other forming a compact 2 × 2 and 4 × 4 MIMO SIW antenna. The proposed design shows a wide bandwidth of 930 MHz (13.74 GHz to 14.67 GHz) and 67.68% impedance bandwidth. The overall size of proposed MIMO SIW antenna is 0.9λo × 0.9λo × 0.024λo, where λo is the operating wavelength. A return loss of 18.4 dB at 14.17 GHz is achieved. The series of metal pins (in plus shape) at the center of 4 × 4 MIMO improves the isolation to 19.6 dB at resonant frequency. A pattern diversity in broadside direction is achieved by the top spiral arms and its complementary spiral arms at the bottom. The beamwidth of the proposed antenna is 90˚ varying from -45 deg to +45 deg, useful for reliable signal transmission and reception. Thus, the proposed antenna is a symmetrical compact design working at Ku band suitable for radio telescope application.
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