Design of multidirection pyramidal 5‐element MIMO antenna for detecting the position of a vehicle in buildings

In this study, a multidirection pyramidal 5‐element antenna is designed to detect vehicle position information in the direction of the total hemisphere in real time. An inverted F and L‐shaped inverted antenna in a three‐dimensional arrangement was mounted on a ceiling of an indoor parking lot. The ground plane was folded into the shape of a square pyramid to direct beams into five different directions and each of them was placed 20–30 m away from the Bluetooth system to secure a stable recognition distance. The total size of the multidirectional antenna was 70 mm × 70 mm × 30 mm, and each antenna (#1–#4: L‐shaped inverted antenna, #5: inverted F antenna) retained the radiated characteristics of a broadside on the ground plane. The average of −10 dB bandwidth in the ISM band was 122 MHz (5%), and the average gain was 2.2 dBi. The four L‐shaped inverted F antennas were able to detect 360 degrees of E ϕ ${{\rm{E}}}_{\phi }$ and E θ ${{\rm{E}}}_{\theta }$ in the Azimuth direction. Moreover, two L‐shaped inverted F antennas and one inverted F antenna formed a beam on the hemisphere in the direction of an elevation, and the average mutual coupling between the antennas was −22.3 dB.