A Miniaturized Two-Element Monopole Mimo Filtantenna Array for V2V Applications

In this paper, we present a new filtantenna design consisting of two wire monopole antennas operating at 3.55 GHz integrated with a planar printed-circuit filter. The antenna array is intended for Vehicle-to-Vehicle (V2V) systems and can be easily installed on moving platforms. The filter is etched from the ground plane of the antenna mounting structure and consists of 25 mm × 15 mm outer rectangular frame that has a width of 0.5 mm. This frame encloses three parallel slots, 24.21 mm in length, inserted symmetrically inside the frame between the coaxial-fed monopole antennas. The slots are 0.5 mm in width and uniformly separated by 0.25 mm. The two monopoles have a height of 17.35 mm each, a diameter of 1.27 mm, both are separated by eight mm, which corresponds to λ/10.56, where λ is the free-space wavelength at 3.55 GHz. The monopoles and the filter are placed on a 90 mm × 90 mm × 3.175 mm RO5880 substrate with a dielectric constant of 2.2 and a loss tangent of 9 ×10 −4 . The filtantenna array provides 26.6% matching impedance bandwidth below −10 dB centered at 3.84 GHz and 18% mutual coupling suppression bandwidth below −20 dB centered at 3.4 GHz. Figure 1 shows the simulated scattering parameters of the proposed filtantenna array design (decoupled antenna array) compared to the same antenna array without the printed-circuit filter (coupled antenna array) The operating bandwidth of the decoupled antenna array over which the matched impedance is below −10 dB and the mutual coupling is below −20 dB is 370 MHz extending from 3.33 GHz to 3.7 GHz. It can be seen that the matching impedance of the coupled array is above −10 dB while and the mutual coupling of the coupled antenna array has been reduced from −5.2 dB to −34.2 dB