| Compared with conventional antennas, Microstrip antenna has many advantages, such as low profile, light weight, easy to conform and integrate. This makes it universally applicated in satellite navigation and communications. At the request of the low profile of the radiator, the microstrip antenna always gets priority use. But microstrip antenna’s power is small and power loss is large.And it can only work on narrow frequency band. These shortcomings greatly constrained its scope of application. In recent years, researchers have focused on finding antennas with excellent characteristics of wideband, high gain, miniaturization, multi-band and the like. So, how to make microstrip antennas with high gain characteristics is a very practical issue. This paper increases the gain of the microstrip antenna by arraying method.This paper presents an X-band radar antenna with high-gain. Its transmit and receive antennas work independently. Antenna and transceiver circuitry are designed in the same metal plate. One side of the metal plate is transmitting and receiving antenna, the other side is a transceiver circuit. It uses a coaxial feed method. The Coaxial connectes power supply circuit and the antenna. Transceiver circuitry and antenna is isolated from the metal plate. Transceiver circuit does not have a huge impact on the radiation of the antenna. Similarly, there is a metal plate between transmit and receive antennas. It not only avoided the mutual influence of the transmitting antenna and receiving antenna, while the metal plate may also establish the directional radiation of electromagnetic waves to improve the gain of the antenna. As can be seen from the simulation, with the influence of the metal plate, antenna gain improved 3dB. Receiving antenna and transmitting antenna are both a linear array with 20 antenna elements, and they are based on the series by the middle of the way to both sides of the feed.There is a T-type power divider at the feed point. The distance of rectangular microstrip antenna element is a guide wavelength. This ensures that each array element receives the feed current with the same phase, and it can help improve the gain of the antenna. In order to improve the level of the main lobe while suppressing sidelobe level, we use Chebyshev polynomials calculated for each array element feeding current amplitude. Each array element is then deduced feeding microstrip line width based on magnitude of the current. Current transfer from the middle of linear array to the sides level. There is a quarter wavelength impedance converter between each level. This can allow the total reflection current is minimum, thereby improving the radiation efficiency of the antenna.In this paper, the resonant frequency of the antenna is 9.6GHz, and the bandwidth is 150 MHz. The antenna gain, 3-dB beamwidth, side-lobe level, and front-to-back ratio were 22 dB, 5.2。, bellow-25 dB, and bellow-30 dB, respectively. Receiving antenna and the transmitting antenna isolation is greater than 57 dB on working Bandwidth The design meets the requirements of radar antenna. |
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