High Isolation Wideband SICL Excited Compact MIMO Antenna Array for 5G Endfire Applications in Customer Premises Equipment

This paper presents Substrate Integrated Coaxial Line (SICL) fed wideband Multiple-Input Multiple-Output (MIMO) antenna array for 5G endfire applications. The radiating element in the array is a modified half-wavelength dipole antenna formed by tilted dipoles at ±45° to avoid overlapping between successive element in the array configuration. One arm is placed on the top while the other arm is placed on the bottom substrate and are respectively fed by top and middle plate (using a feeding via) of SICL line. The out of phase surface current of SICL feed line is utilized to successfully excite the dipole antenna. The top-bottom arrangement of the arms of the dipole antenna enables further compactness in the dimension of the array. SICL technology adds another advantage by reducing the coupling in the other port when one port is excited thereby high isolation is achieved using SICL. A four element MIMO antenna array for 360° azimuth coverage is proposed to exhibit a gain of 6 dBi with wide impedance bandwidth of 5.6 GHz and cross-polarization level below 13.6 dB at 28 GHz. The proposed MIMO antenna array is a potential candidate for 5G endfire applications in customer premises equipments (CPEs).