Abstract-A Substrate integrated waveguide bandpass filter is presented with a novel CPW-to-SIW transition at both the input and output ports which also served as the input and output couplings into the filter. The CPW-to-SIW transition structures presented here exploited the step impedance between the 50 ohms input/output feedline and the transition to control the input/output couplings of the filter. The SIW filter is also shown to have very minimum milling or etching requirement which reduces the fabrication error. The proposed SIW filter has been validated experimentally and results presented. The results show that a simulated return loss of 15 dB and an initial measured return loss of 16 dB were achieved. An improved measured return loss of 22 dB was later achieved after some tuining adjustments were performed on the filter input and output couplings. A minimum insertion loss of 1.3 dB was also achieved across the band.

Abstract-A microwave diplexer implemented by using the twenty-first century substrate integrated waveguide (SIW) transmission line technology is presented. No separate junction (be it resonant or nonresonant) was used in achieving the diplexer, as the use of an external junction for energy distribution in a diplexer normally increases design complexity and leads to a bulky device. The design also featured a novel input/output coupling technique at the transmit and receive sides of the diplexer. The proposed SIW diplexer has been simulated using the full-wave finite element method (FEM), Keysight electromagnetic professional (EMPro) 3D simulator. The design has also been validated experimentally and results presented. Simulated and measured results show good agreement. The measured minimum insertion losses achieved on transmit and receive channels of the diplexer are 2.86 dB and 2.91 dB, respectively. The measured band isolation between the two channels is better than 50 dB.

This paper presents a substrate integrated waveguide (SIW) Chebyshev bandpass filter using the low cost, commercially available printed circuit board (PCB) technology. The detailed design procedure beginning from the normalized Chebyshev lowpass filter, to the final optimized SIW bandpass filter is presented. The test filter having a 4% fractional bandwidth centered at 1.684 GHz was fabricated on a 1.27 mm thick, Rogers RT/Duroid 6010LM substrate with a 10.8 dielectric constant. The design has also been experimentally validated and results presented. The simulation and measurement responses of the filter show good agreement with a low insertion loss of 1.3 dB. The simulated and the measured return losses of about 15 dB and 16 dB respectively, were achieved across the filter passband.

A microstrip power splitter with band-pass responses is presented in this paper. The design is based on square open loop resonator topology. This filtered power splitter does not require quarter wavelength transformers and will result in a smaller size than a conventional Wilkinson power divider with integrated band-pass filter. It is a two-way equal power splitter with fifth order band-pass filter characteristics. The power splitter is designed to have Chebyshev band-pass response function. A theoretical analytical circuit model will be presented. From the theoretical model, a microstrip filtered power splitter will be designed and simulated. The proposed filtered power splitter is small in size and reduces circuit complexity. The power splitter is simulated and measured, and the results are presented.

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