Wideband Series-Fed Patch Antenna Array With High Gain and Low Sidelobe: Linearly and Circularly Polarized for 5G V2X Applications

This paper presents a single-element linearly polarized (LP) patch antenna characterized by a wide impedance bandwidth and low profile, optimized for 5G V2X applications. By inserting air gaps into the LP patch antenna structure, a circularly polarized (CP) antenna is generated. Moreover, a cross-stubs technique is employed to generate CP from LP, thereby enhancing the axial ratio (AR) bandwidth. In this work, we consider both linear and circular polarization patch antennas designed to operate suitable for V2X applications. The resonating structure for both antennas is designed on a 0.787 mm Rogers RT-duroid 5880 substrate with a relative permittivity of 2.2. The proposed design demonstrates resonance within the frequency range of 24 to 34 GHz and an AR bandwidth from 26.4 to 32.1 GHz. Additionally, the proposed design achieves a realized gain of 5.5 dBi along with a radiation efficiency of 94%. To extend the antenna’s gain capabilities, the single-element CP antenna is transformed into a series-fed 9-element array, achieving a maximum realized gain reaching 15.2 dBi and sidelobe levels (SLL) exceeding -17 dB. All proposed antennas are simulated, followed by fabrication and measurements, with the results demonstrating a good level of agreement between simulation and measurement. The proposed antennas’ low profile, wideband performance, and fabrication simplicity position them as ideal candidates for enhancing connectivity in next-generation V2X communications within the millimeter wave (mmWave) band.