Millimeter-wave Broadband Frequency Doubling Technology

The millimeter-wave broadband frequency multiplier is a key component in millimeter-wave source. This paper overall viewed the historical development, future trend, active devices, theory of frequency multipliers and their features. Then severalkinds of broadband frequency multipliers were given, and the theory of NLTL(nonlineartransmission line) frequency multiplier and balance frequency multiplier by two anti-parallel connection diodes were discussed in detail . According to practical application, this paper mainly focused on two different kinds of millimeter broadband frequency multipliers: one is V band tripler and the other is Ka band doubler.The thipler operating in V band is realized by the NLTL consisting of several varactor diodes loading in a length of finline. After the model of NLTL considering finline skin-losses resistance and diodes series resistance was presented, time-domain computer simulation of the tripler was performed. Moreover, a novel design concept was described, which means set the NLTL in the waveguide that smaller than input waveguide and larger than output waveguide. As a result, it can decrease the effects of discontinuity and increase the tripler performance. The experimental results were obtained and analyzed, and some improving methods were given.In the Ka band frequency doubler design, the scheme of balance type was used. Based on the results of the theory analysis and computer simulation of circuits, containing suspended stripline low pass filter and the transition from waveguide to finline, the structure design was presented and products were made. The test results match the requirement quite well, and the circuit is suitable for practical application due to it's simpleness.