Design of a Compact and Wideband Printed Monopole Antenna With Stable Omnidirectional Radiation Patterns

A novel printed monopole antenna is proposed in this letter, which is composed of a monopole radiator and a feeding structure. The proposed feeding structure along the feed line, consisting of a metasurface and two arms, can regulate the surface currents on the ground to stabilize the radiation pattern and adjust the impedance matching of the radiator, respectively. Consequently, a broad operating bandwidth can be achieved due to these combined structures. A prototype is fabricated based on this design, and a wide bandwidth of 0.95-5.2 GHz for |S-11| < -10 dB is observed. The planar dimension of this prototype is 0.3 lambda(max)(95 mm) x 0.046 lambda(max)(15 mm), where lambda(max) is the wavelength corresponding to the lowest operating frequency. The measured peak realized gain ranges from 0.8 to 5.7 dBi, and a stable omnidirectional radiation pattern is observed across its operating bandwidth.