Single-Layer, Unidirectional, Broadside-Radiating Planar Quadrupole Antenna for 5G IoT Applications

In this article, an innovative quadrupole-based broadside-radiating unidirectional antenna is designed at 28.475 GHz for fifth-generation (5G) Internet of Things (IoT) applications. The planar antenna is based on a single-layer technology and realized on a flexible substrate to facilitate conformal applications. It consists of a coax-fed-driven dipole and two quadrupolar near-field resonant parasitic (NFRP) elements. The broadside-radiating design achieves a unidirectional pattern with a realized gain of 4.85 dBi and a front-to-back ratio of 9.4 dB. The total efficiency of the antenna is 85%. A differential-fed prototype was designed, fabricated, and tested at 1.579 GHz to make the measurements more manageable. The measured and simulated results are in good agreement.