The Research Of Microwave Passive Components Based On Substrate Integrated Waveguide

Microstrip and waveguide are two important kinds of microwave and millimeter-wave transmission lines. As a planar structure, microstrip fit for integrity, but its loss is high. On the other hand, waveguide has high Q and low loss but hard to be integrated for their huge volume. Substrate integrated waveguide(SIW) is an new kind of microwave transmission line in these years which can be widely used in microwave and millimeter wave circuits. The substrate integrated waveguide borrow advantages of both of the rectangular waveguide and the microstrip, such as, high Q, low loss just like rectangular waveguide; small size,low profile, low cost, easy to be integrated like microstrip. Designing high performance microwave and millimeter wave components with this technology are investigated and make them to be used in microwave and millimeter-wave system. Since the new concept photonic crystal has been put forward by Yablonoviteh and John independently in 1987 the application of photonic band gap (PBG) structures in the MMIC (Microwave and Millimeter-wave Integrated Circuits) have emerged as a hot pot for research and development. The place that exists in PBG structures is similar with the bandgap in semiconductor called photonic band gap. PBG structures have enormous advantages that can't be substitutable in the easier integration, greatly reduced hardware size, weight as well as cost of microwave circuit.In Chapter 3, the transmission property and the guided-wave structure of the Substrate Integrated Waveguide (SIW) are introduced first, comparing the Substrate Integrated Waveguide with the rectangular waveguide to analyze its transmission characteristics. Then, introduce the transmission characteristics of photonic band gap (PBG), a novel butterfly-shaped PBG filter and rectangular split ring PBG filter are presented, the two filters'prototype are fabricated by standard PCB process and measured by the vector network analyzer. The rectangular split ring PBG filter's measured results show 1.6dB minimal insertion loss from 3.8GHz to 6.5GHz,about 54% fractional bandwidth. The measured results are in good agreement with the simulated results. The measured results of butterfly-shaped PBG demonstrate that the center frequency is 4.78GHz, during the passband, the maximal insertion loss is less than -1.346dB, the maximal return loss is-10.87dB. A novel guided-wave structure called half mode substrate integrated waveguide (HMSIW), which not only retains the advantages of SIW such as low insertion loss, and high power handling capacity etc, but also shrinks the component size by nearly a half. Second, a diplexer based an HMSIW and T-shaped PBG structure is designed, the measured results of filter demonstrate that the filter not only contains good characteristics, but also with a nearly half reduction in size compared with the original SIW version, can meet the need of miniaturization.In Chapter 4, Compared with the design method of T-shaped waveguide power divider with an inductive post, and the design principle of integrated waveguide (SIW), a substrate integrated waveguide (SIW) power divider with an inductive post is proposed. The filter's center frequency is 7.6GHz, maximal return loss is less than -14dB from 7.1GHz to 8.1GHz. Last, a diplexer based on HMSIW-PBG is developed, the up and down channels are composed with HMSIW-PBG filters, the channel 1 has a centre frequency of 6.4GHz, with bandwidth from 6.16GHz to 6.64GHz and the channel 2 has a centre frequency of 7.9GHz, with bandwidth from7.63GHz to8.17GHz .The return loss is less than -15dB for channel 2, and is less than -11dB for channel 1. The simulated results show moderate insert losses and small return losses in passbands. The diplexer takes a planar form and can be easily integrated in microwave integrated circuits.In Chapter 5, the summary of the whole dissertation is given, and future research topics are suggested.