Analysis and Design of V2X Filtenna With Two Independently Controllable Radiation Nulls

This article proposes a dual-mode vehicle-to-everything (V2X) filtenna design, which is equivalent to cross-coupling and nonresonant node (NRN) filtering circuit. The filtenna is first designed with the guidance of the cross-coupling circuit. The radiation null can be manipulated by changing the type and strength of electromagnetic (EM) coupling. In addition, by exploiting the dual model of the cross-coupling circuit, the radiation null can be flexibly shifted to either side of the passband. Furthermore, to realize one more radiation null, a dual-mode model is studied. Its current can be decomposed into common and differential modes, which are excited by electric and magnetic couplings, respectively. Then, the dual-mode model is further evolved to realize a V2X filtenna. In this model, the common mode radiates the RF power to the air, forming a cross-coupling circuit. While the differential mode realizes an NRN filtering circuit, generating a new resonance and radiation null. Guided by the circuital characteristics, a second-order dual-mode V2X filtenna is designed, simulated, and fabricated for validation. The filtenna is measured in the V2X band (5850–5925 MHz), realizing a gain of 4 dBi, an omnidirectional radiation pattern, and an out-of-band suppression over 14.9 dB (0.65–5 GHz), 20 dB (5–5.6 GHz), and 20.56 dB (6.3–7.3 GHz).