V 頻帶次諧波混波器

Abstract

本論文中，我們設計了一個 V頻帶 (50-75 GHz)次諧波混波器，在 V頻帶 附近其大氣吸收衰減非常大，故非常適合保密及區域通信，可避免頻率的 干擾及雍塞等現象。並且次諧波混波器所需的本地振盪器頻率是一般混波 器的一半，對於毫米波昂貴的波源，的確可以減低成本。本論文並且討論 次諧波混波器偶次諧波的抑制及低AM雜訊等優點。這些優點使該混波器非 常適合毫米波的應用。此混波器中包含懸吊微帶線低通濾波器的設計製作 及量測。其量測結果與設計十分接近。在整個混波器設計中我們利用電腦 輔助設計軟體LIBRA 來達到最好的結果。實驗結果顯示，混波器的轉換損 失低於10dB，在RF輸入頻率範圍在51.5-53GHz，LO輸入頻率為31.9 GHz ，當LO輸入功率為14dBm In this thesis, we designed a V band (50-75GHz) subharmonic mixer. The atmospheric attenuation is very large near V band. Thus, it is very suitable for security and local communication to reduce the interference and jamming. The LO frequency is half of conventional mixer needed for subharmonic mixer. For millimeter wave application, the LO sources are so prohibitively expensive, so it can reduce the cost. Besides, we discuss the suppression of the even harmonics and AM noise. These advantages of subharmonic mixer that make it very suitable for millimeter waves appllications. This circuit includes a suspended stripline low pass filter design. The measurement results of this filter compared closely with the design values. In the whole mixer design, we use the CAD software HP-EESOF's Libra to obtain the best performance. The measured conversion loss is lower than 10 dB within RF frequency 51.5-53 GHz, and LO frequency 31.9 GHz at LO power 14 dBm. This compare well with M. Cohn's result in 1975, which show a V band subharmonic mixer with the 8 dB conversion loss.