In this paper, a high-gain wideband parasitic microstrip antenna, for 5G and IoT applications at 26 GHz, is presented. Firstly, a single antenna, composed of a miniaturised
parasitic patch antenna, has been studied, characterised and optimised to operate at 26 GHz, aiming at the 5G new radio (NR) frequency range 2 (FR2) band n258. The proposed antenna uses eight microstrip patches as parasitics, in a squared layout, surrounding a central probe-fed patch. The patches operating as parasite elements are coupled by the magnetic and electric field created by the central active patch. According to simulations, a single optimised array antenna has a total dimension of 24×24 mm2, corresponding to 2:1 × 2:1 λ of the operating frequency, exhibiting an effective gain of 14.4 dBi and total bandwidth 4.15 GHz (16.29%), after optimisation in CST MWS