Investigation On SINRD Waveguide Circuits Directly Fabricated On PCBs

With the development of microwave circuits towards the higher working frequency, single planar circuit can not be designed as millimeter-wave integrated circuits. For the structure of nonradiative dielectric(NRD) waveguide, the space of two metal plates is less than an half of wavelength in free space. Therefore, the electromagnetic wave is in the cutoff mode. Because the introduction of the dielectric strip changes guided wavelength, electromagnetic wave can transmit through the dielectric strip, and the radiation loss will quickly decay to zero. As a result, it can almost completely suppress the radiation loss at bent and discontinuities. Due to the characteristics of its working main mode(LSM11), the nonradiative dielectric waveguide has the lower metal loss and is very suitable for millimeter-wave circuits.Based on the concept of NRD waveguide, derived eigen-equations and substrate integrated technology, the substrate integrated nonradiative dielectric waveguide(SINRD) is discussed in this thesis. By delicatedly choosing the working frequency and reasonably designing air via-holes of the SINRD waveguide, the SINRD waveguide can be fulfilled with good property. It is easy to integrate SINRD circuit on multilayered microwave and millimeter wave planar circuits. A novel transition from coplanar waveguide(CPW) to slotline is presented, which utilizes conduct vias and metal strips to connect two ground planes of CPW instead of air bridges. Due to the absence of the air bridges, the transition can be integrated on multilayered circuits. And a broadband transition from CPW to SINRD waveguide is proposed, and they are connected by slotline.In addition, the transition from CPW to SINRD waveguide is utilized to realize a bandpass filter based on aperture coupling theory. By choosing appropriate air via-holes on the central dielectric strip, a bandpass filter with good property can be obtained.