Research On SIW_based W-band Millimeter Wave Power Combining Technologies

High power amplifier is indispensible key component in the transmitter of the wireless communication system. With the rapid development toward the higher frequency of wireless communication system, the demand for higher frequency, higher efficiency, greater bandwidth, more power capacity devices grows with each passing day. But with the increasing of frequency, the size and power capacity of the solid state power devices are significantly reduced, single solid power device is difficult to meet the requirements of the system. To this end, the power combining technologies are usually used to achieve higher power in the transmitting system. Since its combining efficiency is hardly affected by the combining number, the spatial combining technology has the remarkable superiority in the multi-channel power combining. Uniting the advantages of a new type of electromagnetic waveguide structure--substrate integrated waveguide(SIW) and the spatial power combining technology, a variety of power combining implementation solutions in millimeter wave band were proposed in this paper. The main results are as follows:Firstly, with the combination of the commonly used rectangular waveguide-microstrip probe transition and gradual linear transition from microstrip to SIW, a broadband probe transition between SIW and RW in W band was proposed, which has the advantages of small volume and simple structure. The test results indicate the reflection coefficient is less than-10 d B of a back-to-back structure in the whole W band, and the total insertion loss is less than 2dB in the frequency range of 75-106 GHz. These data illustrate that this transition has the characteristics of low loss and broad bandwidth.Secondly, from the analysis of the slotted SIW, on the premise of the traveling-wave power synthesis theory, a 4-way traveling wave power combiner based on slotted SIW in the W band was proposed for the first time. The combiner works around 88- 94.2 GHz, its insertion loss is between 0.34 dB and 0.73 dB. It has the characteristics of easy integration implementation, relatively broader bandwidth, lower insertion loss, higher combining efficiency, and easier channel extension.Thirdly, based on the double layer SIW broadside slot coupler, a 2-layer-SIW 4-way power combiner in W band was proposed for the first time. Because the coupling occurs in the internal SIW, and thanks to the high isolation character of the coupler, the combiner enjoys the advantages of lower loss, higher efficiency, wider bandand, and smaller lateral size etc..Lastly, a 4-layer-SIW 4-way power combiner in W band was put forward on the basis of the transition structure of multilayer SIW and RW. Using waveguide spatial power combining technique, this combiner not only possesses the advantages of lower loss broadband, higher combining efficiency, simpler structure, and the combining efficiency is barely affected by the change of the combining channel.