Dual-antenna system composed of patch array and open-ended waveguide for eliminating blindness of wireless communications

1. Abstract: In mobile communications in urban area, it is a significant problem that blind spots of in the narrow street are caused by high buildings. In our previous works, a reflectarray antenna was developed to solve the problem [1]. However, the gain of reflectarray becomes very low when a very broad scattering angle is required. In this research, a new dual-antenna system is proposed, including a receiving and a reradiating antenna to realize a broad-angle beam control. An equivalent bistatic radar cross section (BRCS) is deduced to evaluate the antenna performance. 2 . Equivalent BRCS and Results: Figure 1 shows the schematic of propagation channel in an urban area, where Antennas #1, #2, #3, and #4 represent the base station, receiving and transmitting antennas of the dual-antenna system, and the user, respectively. In this design, the electromagnetic (EM) waves for downlink propagate as follows: first, Antenna #2 receives the EM wave from the base station; then, the received wave is guided by a low-loss transmission line and reradiated by Antenna #3, and finally received by Antenna #4. Here the dual-antenna system can be evaluated in terms of an equivalent BRCS, just similar to an ordinary scattering object. The channel gain can be calculated by two methods: Friis transmission equation and radar range equation, as shown in Figure 1, where Gt1, Gr2, Gt3, and Gr4 are gains of Antennas #1, #2, #3, and #4, respectively, and σeq is the equivalent BRCS of the proposed dual-antenna system and λ is the free-space wavelength at the operating frequency. Then, σeq can be calculated by