Modeling and design of improved-gain wideband magneto-electric dipole antenna for micro-BTS applications

Abstract

A wideband Magneto-Electric Dipole (MED) antenna with high gain is proposed for the 700/800/850/900 MHz frequency bands for cellular network applications. The antenna comprises a half-wavelength bow-tie-shaped dipole, an elongated magnetic loop and a ground reflector with four Elevated Ground Planes (EGPs) at reflector's corners. The EGPs enhance the antenna gain and Front-to-Back Ratio (FBR), which is a promising technique in the MED antenna design. The antenna is excited by a Γ-shaped coupling element. An analytical model of the proposed antenna is developed by employing Schelkunoff's model for dipole antennas and the transmission line theory complemented by radiation resistance corrections. The antenna design is validated with full-wave numerical simulations. The antenna is fabricated using cut and bent metallic plates and tested in an anechoic chamber. The analytical, numerical and experimental results are in a good agreement. The experimental results confirm that the proposed MED antenna with dimensions of 1.44λ × 1.44λ × 0.27λ achieves a bandwidth of 61.53% (623.1–1176.8 MHz) for VSWR < 1.5 and a stable gain of 9.8 ± 1.9 dBi. By employing the EGPs, the realized peak gain and FBR are enhanced by 0.52 dBi and 1.1 dB, respectively.