Design and Analysis of Rat-Race Coupler for 5G MIMO Antenna System Applications

In this work, design and analysis of a rat race coupler (RRC) for 5G MIMO systems operating at 3.5 GHz. The RRC and rectangular patch array MIMO antenna design are utilized for transmitter and receiver applications. That enables 5G operation. The three components of the proposed antenna are constructed using a traditional rectangular patch antenna and linked in series with a quarter wave feed line and a
$50 \Omega$
impedance line. The same array antenna is used to build a two-port MIMO antenna that operates at a frequency of 3.5 GHz. It provides a compact size, excellent isolation, and low insertion loss, making it an ideal solution. The coupler, measuring
$32.6\times 33.2 \text{mm}^{2}$
, provides a minimum reflection rate of −3 dB, a return loss of over −30 dB, an isolation loss of less than −20 dB, and an excellent coupling coefficient. The antenna has the gain of 5.5 dBi, a return loss of 30 dB, and a bidirectional pattern and isolation of more than −20 dB. The proposed work can be used in 5G MIMO system applications.