具有抑制反射波束主動式回授微帶漏波天線與頻率合成器之整合

Abstract

近年來，在微波與毫米波應用領域中，汽車防撞雷達/感應器已經變成一門重要而且令人感興趣的話題。在這方面，我們也設計了另外一種工作於X-band汽車防撞雷達的發射架構。這個發射電路具有下列優點：小尺寸，架構簡單，製造容易，而且發射天線能夠有效抑制反射波束高達15 dB，此外，當饋入天線頻率改變120 MHz，所對應的發射主波束能夠掃瞄約5度左右。之後，我們改變饋入架構，整個發射電路的面積能夠大量的縮小。 這個發射電路由頻率合成器整合一支微帶漏波天線所形成。並且利用混成電路技術完成製作。其操作頻率範圍從9.25 GHz到9.37 GHz，其操作頻寬約120 MHz左右。藉由適當的程式控制，一方面可以改變頻率輸出，進而控制主波束角度以期達成方位掃瞄功用。同時另一方面還可形成類似於FM-CW的數位波形，以便計算出障礙物的速度，距離，以及解析度。之後，考慮到面積問題，我們改變了天線饋入架構，改由背面孔隙饋入，如此一來大大縮小了發射電路面積。

In the recent year, the automotive collision avoidance radar is the hot topic. There are many units experimenting with various radar systems in the past two decades. Hence, we plan to develop an automotive collision avoidance radar with planar antenna being operated in X-band. The transmit part of the X-band radar is made up of an X-band synthesizer with a leaky-wave antenna. And the antenna can scan over a certain angle range and have suppressed back lobe at the same time. By the frequency synthesizer structure, we achieve the goal. A feedback synthesizer antenna was designed, the measured radiated power difference between the main beam and back lobe is more than 15 dB at 9.25 GHz, and the scanning angle is about 5 degree as the synthesizer frequency sweeps from 9.25 GHz to 9.37 GHz. To reduce the area of the original transmit circuit, the structure of the side-fed by aperture-coupled LWA integrating with the frequency synthesizer is designed.