Gain Improvement and Front-to-Back Ratio Enhancement for Substrate-Integrated Magnetoelectric Dipole Antenna

A two-layer substrate-integrated magnetoelectric dipole antenna is proposed in this letter. The problem of the gain on the high operating band dropping dramatically is analyzed and solved. The weakening of gain is caused by the conflict of neighboring resonances, which come from two different sources of the magnetic dipole. The shorting pins enhance the gain up to about 6.5 dB by tuning the conflicting resonances at the high operating band. Furthermore, the shorting pins reduce the operating frequency and increase the impedance bandwidth. The different arrangements of shorting pins are also compared and analyzed. The high passing property of the vertical split-ring resonator (VSRR) on the wide region is utilized to improve the front-to-back ratio at least -2.1 dB over the wideband. In addition, the gain on the lower operating band is also enhanced by the shorting pings and the VSRRs. The measurement of the prototype fabricated shows that this antenna obtains a wide impedance bandwidth of 73.8% for VSWR <= 2 from 3.16 to 6.86 GHz and a stable gain ranging from 7.8 to 9.8 dBi. The proposed antenna is suitable for efficient mass production with low cost by the printed circuit board technology and promising for 5G applications.