A Millimeter-Wave Ultrawideband Tightly Coupled Dipole Array Antenna for Vehicle Communication

Abstract

This letter presents a millimeter-wave (mmWave) ultrawideband tightly coupled dipole array (TCDA) for vehicle communication. The designed array antenna has eight dipole unit cells arranged in one dimension. A special Marchand balun with comb-type perforated structure is developed to realize the unbalance-to-balance transformation and match the impedance. The proposed unit cell of the array achieves a 1:7.6 bandwidth (5.7 GHz--43.3 GHz) with active reflection coefficient less than −6 dB during the simulation. Meanwhile, the antenna achieves a low profile of 0.087 λl, where λl is the free-space wavelength at the lower cut-off frequency. Then, a prototype with scanning angle up to 45° is fabricated and measured to validate the proposed structure. The measured realized gain of the array is 8 dBi at the center frequency of 18 GHz. The measured and simulated results are in good agreement, which confirms the simulation results and validate the proposed design.