A novel wideband slot loaded microstrip patch antenna through reallocation of TM1,0, modified TM0,2 and TM1,2 modes

Abstract

This paper presents a novel wideband microstrip patch antenna (MPA) characterised by a straightforward structure and operational efficacy across four resonances. The antenna consists of a truncated square patch, a coplanar capacitive feed and a slot on the patch. The square radiating patch is strategically truncated at its four corners to perturb the electric field distribution characteristic of the TM_0,2 mode, thereby facilitating the generation of a unidirectional far-field pattern. Extensive analysis has elucidated the mechanism through which corner truncation diminishes the electric field peak associated with the TM_0,2 mode at the centre, resulting in the transformation of the dual-beam pattern into a distinct single beam pattern. In addition, unlike conventional approaches that require additional components such as shorting pins, this approach reallocates three radiative modes—specifically TM_1,0, TM_0,2, and TM_1,2—resulting in a simplified structure. Finally, a coplanar capacitive feed and a slot are employed to boost the input impedance frequency bandwidth and generate the fourth resonance, respectively. Therefore, four adjacent resonances are simultaneously excited by this method and a wide frequency bandwidth of approximately 80% with stable unidirectional radiation pattern and same polarisation are fulfilled. A prototype of the antenna is fabricated and measured to validate the design procedure.