具有单向辐射特性的低剖面、宽带/超宽带圆极化微带天线设计

Traditional ultra wideband (UWB) antennas, including Vivaldi antenna, dipole antenna, spiral antenna and slot antenna, have omnidirectional radiation pattern. In order to achieve unidirectional radiation pattern, a reflector underneath the antenna is required. However, it enlarged the profile of the antenna and causes serious size problem of UWB antenna. Microstrip patch antenna has the feature of low profile and unidirectional radiation which could solve this problem. However its inherently narrow bandwidth limits its application in UWB field. In order to solve this problem. Firstly, a detailed analysis of multi mode combination theory is made. A new method is found in order to decease the resonant frequency of higher modes. Theoretically, infinity mode can be combined together and the bandwidth of the patch antenna can be significant increased. Secondly, an engineered improvement is made in order to utilized this novel multi mode combination technique. Lastly, another improvement is made in order to change the proposed antenna into a circularly polarized wideband patch antenna with wideband phase shifter. By employing the design method. the bandwidth problem of patch antenna is overcome and the low profile UWB patch antenna with circularly polarized and unidirectional radiation pattern is achieved.

传统超宽带天线（包括vivaldi天线，偶极子天线，螺旋天线，开槽天线）往往具有全向辐射的方向图，为了产生单向辐射方向图以提高增益，减小对后端设备干扰，往往通过增加反射板的方法实现，但是这导致天线剖面过大，占据很大空间，对天线小型化带来严重问题。微带天线是一种天然的低剖面单向辐射天线，可以有效解决上述问题，但由于其辐射机理导致的带宽较窄问题限制了其在超宽带天线领域的应用，针对此问题，本项目首先对微带天线多模融合理论进行深入研究和剖析，找到一种高次模下移方法，使得微带天线从理论上可以融合无限多个模式。再对这种设计方法在微带天线上进行实际工程化改进，设计基于此方法的超宽带线极化微带天线，最后通过对天线结构进一步改进，并设计宽带圆极化微带天线，这种全新的设计方法对微带天线进行设计，旨在克服微带天线带宽较窄，难以实现超宽带的问题。最终实现具有单向辐射特性的低剖面、宽带/超宽带圆极化微带天线。

传统超宽带天线（包括vivaldi天线，偶极子天线，螺旋天线，开槽天线）往往具有全向辐射的方向图，为了产生单向辐射方向图以提高增益，减小对后端设备干扰，往往通过增加反射板的方法实现，但是这导致天线剖面过大，占据很大空间，对天线小型化带来严重问题。微带天线是一种天然的低剖面单向辐射天线，可以有效解决上述问题，但由于其辐射机理导致的带宽较窄问题限制了其在超宽带天线领域的应用，针对此问题，本项目首先对微带天线多模融合理论进行深入研究和剖析，找到一种高次模下移方法，使得微带天线从理论上可以融合无限多个模式。再对这种设计方法在微带天线上进行实际工程化改进，设计基于此方法的超宽带线极化微带天线，最后通过对天线结构进一步改进，并设计宽带圆极化微带天线，这种全新的设计方法对微带天线进行设计，旨在克服微带天线带宽较窄，难以实现超宽带的问题。最终实现具有单向辐射特性的低剖面、宽带/超宽带圆极化微带天线。