The Research On The Theory And Technologies Of Ka-band Millimeter-wave MIMO Antennas

With the rapid developement of wireless communication technologies in recent years, the demand for business type and quality in mobile communication systems is increasing,and Scarce spectrum resources has become a bottleneck in the development of telecommunication. Without sacrificing additional spectrum or transmitted power in rich multi-path environments, MIMO(Multiple-Input Multiple-Output) technology has potentiality of increasing channel capacity and improving the quality of mobile communication systems. Thanks to the developement of mobile communication, the MIMO system for millimeter-wave application also arises at the historic moment. MIMO antenna as key components of the MIMO system has a big effcet on the performance on the whole system, so, the design of millimeter wave MIMO antennas has important reserach significance.This article first expounds the working principle and basic parameters of microstrip antenna, and the theory of the MIMO antenna including the main parameter, design requirements and channel capacity system is introduced, which laid a foundation for reasonable design of MIMO antenna.Secondly, this paper proposes a circle diameter 2x2 millimeter wave MIMO antennas structure. The result of simulation shows that the bandwidth of the millimeter-wave MIMO antennas is greater than 10%,it makes a considerable improvement of antenna gain at center frequency and side lobe suppression, isolation was improved by means of adding wave director above the antenna and cutting a oblique 45 ° cross slots..In order to verify the antenna performance, we process> assemble and test the antenna. Test results show that the bandwidth of antenna is 33GHz-36GHz (|S11|≤10dB), the gain is 12dB at 35 GHz and sidelobe level is better than-12 dB, the results are basically consistent with the design.Finally, this article designs a rectangular 1x4 millimeter wave MIMO antennas for monolithic integrated in Ka-band. This antenna use the nonradiation boundary feed and composed of four rectangular patch, as the array element of MIMO antennas, the simulation results show that the bandwidth of the antenna is 34.13GHz-35.77GHz, gain is 13.45dB, sidelobe level is better than that of-15 dB and isolation is better than 32 dB. In order to validate the structure proformance, we process and test the antenna, the experimental results show that the bandwidth is 34.38GHz-35.42GHz(|S11|≤-10dB), the antenna’s port isolation reached 34.6dB at the center frequency 35GHz. The sidelobe of E plane is high,reach -9dB, and H plane is correspond to simulation.