Substrate integrated waveguide (SIW) components: transition with identical steps and broadband Y-type divider

Substrate integrated waveguide (SIW) technology has attracted significant attention in recent decades. Substrate integrated waveguides combine the high-power capability of the rectangular waveguides (RWG) with the low profile of the planar technology. In this thesis, two SIW components are designed, fabricated, and measured. The first design is an in-line transition between SIW and RWG. Most in-line transitions are metallic with steps of different heights. In this thesis, an SIW transition in K-band is proposed, where the transition part is made of printed circuit board (PCB) panels and the steps are identical. To provide the height of the steps equal to the thickness of the panel, a novel 1:2 E-plane step is designed, by profiling the widths along the midline. Based on the proposed 1:2 E-plane step, a cascaded network is developed to reach the height of waveguide. This cascaded network is then connected to an air-filled SIW taper. The proposed transition in the back-to-back form is fabricated for the measurement, and the results show 15 dB return loss for the frequency range from 20.14 to 25.84 GHz. Such SIW transition with identical steps allows the fabrication on PCB panels, achieving reduced complexity, lighter weight and lower cost. The second design is about a bandwidth enlargement method of the SIW Y-type power divider. In most Y-type dividers, the TE30 mode either degenerates in-band reflection or limits the frequency band of operation due to a transmission zero. The transmission zero is analysed and the mode coupling is utilized to reduce its impact. In the presented configuration, the co-existence of the TE10 and TE30 modes combines the two non-contiguous bands which were separated by the transmission zero. A broadband balun based on the proposed method is designed and fabricated. The measurement shows 15 dB return loss for the frequency range from 8.23 to 12.89 GHz. The measured amplitude and phase imbalance are below 0.7 dB and ± 3 degrees, respectively. The fabricated balun reveals performance, consistent with the simulation, and demonstrates the validity of the applied broadband enlargement method