A low-profile wideband microstrip patch antenna using double half-mode resonances

This paper presents a miniaturized broadband microstrip patch antenna with a simple geometry. The radiation patch of this antenna comprises two rectangular patches with slightly different sizes, one side of each patch is grounded by metal via-holes. Two rectangular patches are connected by a microstrip line and fed by a single port. Two rectangular patches produce two closely resonant frequencies achieving broadband performance. This antenna operates on the resonant method of short-circuiting on one side. Metal via-holes act as a short-circuit wall allowing each patch to operate in TM0.5,0 mode. The size of a 1/4 wavelength resonant patch is only half of a conventional microstrip antenna, the overall size of this antenna is almost as same as a conventional rectangular microstrip antenna, making it compact in size. The wideband is achieved by combining two radiating patches, resulting in stable radiation and flat gain. Measurement results show that the antenna has an impedance bandwidth of 4.35- $-$5.10 GHz (15.8%) using a common dielectric substrate without air layer thickness additionally. The maximum measured realized gain is 4.61 dB. This antenna has advantages of wide bandwidth, low profile, flat gain and ease of manufacturing.