Narrow transverse‐size compact vertically polarized end‐fire antenna using dual‐hat composite elements

Abstract

A narrow transverse-size compact end-fire antenna with vertical polarization (VP) is presented in this paper. The antenna working in the 433 MHz band is constructed based on a dual-hat composite element, which consists of a rectangular and a pentagon top hat. This is operated in terms of capacitive coupling and inductive loading. Two dual-hat composite elements are, respectively, applied as the driven and the reflector elements in a Yagi array layout, and they are arranged in a noncommon ground manner. The main radiators are the posts with VP radiation fields, which are readily affected by electromagnetic coupling from the adjacent elements. The radiation fields are constructively guided and overlapped to generate an end-fire radiation. The resonant length of the antenna is stretched due to a folded current path with a reduced profile height. The measured |S11| < −10 dB impedance bandwidth (IMBW) for the fabricated antenna ranges from 419 to 444 MHz (5.7%) and the measured end-fire peak gain can go up to 2.2 dBi at 433 MHz. The antenna dimensions can be maintained at 0.37λ0 × 0.16λ0 × 0.051λ0, where λ0 is the free-space wavelength at the center frequency. It exhibits narrow transverse size and compact structure.