Design of Simple Broadband Millimeter-Wave Monopole Antenna using Substrate Integrated Coaxial Line (SICL) Technology

A novel monopole antenna fed through a substrate-integrated coaxial line (SICL) is proposed in this paper. It offers advantages such as broad bandwidth (BW), non-dispersive, easy design, and compact size. The antenna is demonstrated for a frequency range of 24.25 to 29.5 GHz, encompassing several millimeter-wave bands (n257, n258, and n261) specified for 5G. The broadband characteristics of the proposed SICL-fed monopole antenna are obtained using a SICL feed and a monopole element implemented over a finite ground plane. The bottom and top metal layers of SICL are employed to implement a ground plane for the monopole element and reflector to direct the radiated fields, respectively. The proposed antenna achieves an impedance BW of 21.5% for the reflection coefficient below -10 dB. Within the operating band, it exhibits stable end-fire radiation patterns with peak realized gains between 4.7 and 5.1 dBi and cross-polarization values below -12 dB.