A Wideband Printed Dipole Antenna With Small Footprint Using a Miniaturized Microstrip-to-Coplanar Strips (CPS) Transition

This letter presents a wideband printed dipole antenna for multistandard mobile communication. The antenna consists of a bow-tie shaped driven element, a parasitic radiator, and a new microstrip-to-coplanar strips transition. Unlike traditional transitions using a phase delay line, the new one utilizes a 180° hybrid having frequency-independent amplitude and phase balance. The replacement enhances the transition bandwidth, minimizes the footprint, and offers a simpler design with fewer design parameters. The measurement results show that the transition has a fractional bandwidth (|S_₁₁| < -10 dB) as wide as 91.9% in a back-to-back configuration. As a result, the antenna achieves the bandwidth of 61.6% with a constant gain of 4.2 dBi ± 0.5 dBi and low cross-polarization level of better than −14.8 dB from 1.5 GHz to 2.5 GHz.