Gain Enhanced Wide Azimuth Beam Antenna Using Half-Mode Substrate Integrated Waveguide Cavity for Automotive Rear-View Mirror Application

This paper presents a gain enhanced wide azimuth beam automotive antenna using half-mode substrate integrated waveguide (HMSIW) cavity for automotive applications. The antenna is separated into two HMSIW cavities by electrical via walls. The two HMSIW cavities are excited through differential feeding, including a 180 <tex-math notation="LaTeX">∘</tex-math> delay line in the center of the antenna. The antenna was operated in <tex-math notation="LaTeX">TM₁₁</tex-math> mode and investigated using aperture theory based on the cavity model. The antenna size is small enough to mount in the rear-view mirror, which has a long rectangular shape. For comparison, the proposed antenna and a conventional 1 × 2 microstrip square patch antenna array were fabricated to the same dimensions. Then, these antennas were tested to provide validation. The tested results were consistent with the simulation results. The tested results show that the antenna, with the overall dimensions of 70 mm × 35 mm × 1.52 mm (1.38 <tex-math notation="LaTeX">λ ₀</tex-math> × 0.69 <tex-math notation="LaTeX">λ ₀</tex-math> × 0.03 <tex-math notation="LaTeX">λ ₀</tex-math> ), operates at 5.9 GHz. The gain of the antenna is 9.49 dB, and the azimuth beam width is 74.0 <tex-math notation="LaTeX">∘</tex-math> . The proposed antenna has a wider azimuth beam width (74.0 <tex-math notation="LaTeX">∘</tex-math> ) than a conventional 1 × 2 square patch array antenna (42.0 <tex-math notation="LaTeX">∘</tex-math> ) with similar gain and size.