A Novel Compact Magneto-Electric Dipole Antenna for Millimeter-Wave Beam Steering Applications

A novel compact magneto-electric (ME) dipole antenna with size of 0.31λ
₀
×0.31λ
₀
×0.12λ
₀
(λ
₀
is the wavelength at central frequency herein and after), gain of around 8 dBi, and bandwidth of 39.7% is presented for millimeter-wave beam steering applications with the combination of the fractal technique and reactive impedance surface (RIS) loading. In particular, a fractal ME dipole antenna with four modified second-order Minikowski structures is firstly designed, where an aperture size of 0.38λ
₀
×0.38λ
₀
is achieved. Herein, the antenna gain is dropped with the size reduction. Then a capacitive RIS structure is designed and loaded to improve the antenna gain and further lower down the antenna operating frequency range. With the RIS structure, the antenna gain is increased by around 4 dB, and the operating center frequency is shifted to left side by 9.0 GHz, thus achieving a further size reduction. Simulation and measurement results are provided to demonstrate the excellent properties of the proposed antenna. Subsequently, the antenna is arranged into a 5 mm-spaced (half wavelength at 30 GHz) 16-element uniform linear array. The beam steering characteristics of the array are investigated with the influence of phase quantization errors into consideration.