A Full Band Millimeter Wave Power Module Using Microstrip to Waveguide 3dB Power Combiner

使用新型3dB功率合成器的全波段毫米波功率合成模块,专业技术资料。

A Full Band Millimeter Wave Power Module Using Microstrip To

Waveguide 3dB Power Splitter/Combiner

Qiuliang Lai, Xiaoqiang Xie, Ruimin Xu

Department of Microwave Engineering College of Electronic Engineering

University of Electronic Science and Technology of China

Chengdu Sichuan China

E-mail:ttr_lql@163.com

Introduction

In recent years, although the MMIC industry has made a great progress in fabricating MMIC power amplifier (PA), the output power of a single MMIC PA is still too low to meet our increasing demands, thus forcing designers resort to vacuum-tubes devices. Fortunately the developing power combing technology relieves the stress of demanding high power and broadband MMIC PA and extensive research activities have been taken in the field of power combining, several spatial and quasi-optical power combining techniques have been proposed for the implement of high power broadband millimeter wave solid state power module [1] -

[3]. As a result of conventional hybrid-type power-combining circuits, like the Wilkson power splitter, Lange coupler, and branch-line coupler, suffer from low power efficiency at millimeter wave frequency band [4], for recent years many power splitters based on waveguide were proposed such as waveguide finline arrays [5] [6], microstrip to waveguide probe splitter [7][8]. Waveguide finline arrays, in spite of its wideband performance, but its complicated structure, not good heat-sinking and sensitivity to the fabrication errors limit its application in millimeter wave frequency band. On the other hand, the probe type splitter not only show wide band performance, low loss, simple structure and easy assemble, but also not sensitivity to the fabricate errors, and becoming a good candidate for wide band power combining. In this paper, to realize broadband power combine, we presents a full band microstrip taper probe splitter/combiner(MTPS/C), which is in the context of WR-28 waveguide and 50 -microstrip line supported by duroid 5880 ( r=2.2, h=0.254mm). The proposed 3dB splitter shows excellent performance across the entire waveguide band. And finally a full band power module is design based upon the splitter/combiner proposed and show excellent performances across the entire band of WR-28.

Design and construction of waveguide 3dB power splitter/combiner

Figure.1 depicts sketch of microstrip taper probe 3dB splitter. The splitter consists of a waveguide input and two microstrip outputs, the microstrip probes are mounted on the center of the broadside of WR-28 waveguide, a maximum electric field at the electric probe is attained by the use of a tunable short. As the power travels down the waveguide structure, equal power coupling is achieved at the taper probes. Based on the design procedure discussed in [8] [9], a taper probe type is proposed for wideband operation in stead of ordinary probe. The taper probe’s broadband instinct can be explained as follows: the extension of a printed microstrip circuit through an aperture in the broad wall couples the energy of the TE10 mode of waveguide into the quasi-TEM microstrip line and achieve impendence transform form waveguide to microstrip, a taper can complete this mission perfectly. We have designed and construct a 3dB splitter and verified with an electromagnetic CAD (HFSS) procedure. All critical physic dimensions are list in table 1. Figure 2 shows the 978-1-4244-2642-3/08/$25.00 ©2008 IEEE