Based On Substrate Integrated Waveguide Passive Components

Microstrip and waveguide are two important kinds of microwave and millimeter-wave transmission line. As a planar structure, microstrip fit for integrity, but its big loss make them not suitable to be used in millimeter wave applications and couldn't compose high Q passive components. On the other hand, waveguide could compose high quality components and low loss but hard to be integrated for their huge volume. Substrate Integrated Waveguide (SIW) is a new kind of microwave transmission line in these years which can be widely used in microwave and millimeter wave circuit. 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.First, the transmission property and the guided-wave structure of the Substrate Integrated Waveguide (SIW) are introduced, comparing the Substrate Integrated Waveguide (SIW) with the rectangular waveguide to analyze its transmission characteristics. Later, three transformers of SIWs' are studied in the paper, solving the coupling of SIWs' to adapt the developing of body circuit. The three transformers are as follows: a single-substrate-different-layer transformer, two transformers of SIWs' coupling on different layers. At the same time, the three transformers are simulated in both microwave band (Ku-band) and millimeter-wave band (Ka-band). Measured results are as follows. single-substrate-different-layer transformer: in the whole Ku-band, the insertion loss is about 1 dB, and the fluctuations are not more than 0.5 dB; S11 is also a good curve, almost every point is lower than -15dB. Equidirectional transformers of SIWs': frequency of 11.4GHz～12.2GHz, and 13.3 GHz～14.2GHz, return loss is better than 20dB. Insertion loss is about -1.5 dB, including the loss of SMA connector.Then, substrate integrated waveguide directional coupler is studied in both microwave band (Ku-band) and millimeter-wave band (Ka-band). The simulation results in CST microwave office demonstrated the design is feasibility and the good performance of the device. At the same time, developed a Ku-band SIW directional coupler, measured results are as follows: S11 is lower than 15 dB in a wide bandwidth; at the same time, from the frequency of 13.3 GHz to 13.6 GHz, S11 is less than -20 dB. In addition, the energy difference is less than 1 dB between port 2 and port 3 in a wide bandwidth. Measured results demonstrated these SIW directional coupler has a lot of merit. At last, a type of SIW filter is designed based on the generalized chebyshev function. The simulation results show that the SIW filter have low insertion loss in passband.