A full Ka-band right-angle transition from a substrate integrated waveguide (SIW) to an air-filled rectangular waveguide is proposed. A twostep ridged waveguide and the SIW with an etched slot are jointly designed to obtain a better electric field and impedance matching between the SIW and the air-filled rectangular waveguide. To verify the method, a back-to-back transition prototype at Ka-band is designed, fabricated and measured. The measured results show that the insertion loss of a single transition is <0.55 dB over the entire Ka-band from 26.5 to 40 GHz. Moreover, the 15 dB fractional bandwidth is increased from 25.7 to 40.9% compared with conventional right-angle SIW-towaveguide transition. This broadband transition can be a good candidate for broadband millimetre-wave applications.
A novel C-band concurrent dual-band oscillator is presented in this paper. Two diplexers are cascaded back-to-back to realize two loop sub-oscillators. The phase noise of the oscillator is reduced significantly by using the cascaded high-Q diplexers as the frequency stabilization elements. Meanwhile, a highly pure dual-band signal was observed at the output port, which is contributed to the isolation characteristic of the diplexers. The diplexers can suppress the interaction between the two sub-oscillators. To obtain the property of compact size and high-Q factor, the SIW-CSRR structure is introduced into the design of diplexers. A C-band prototype has been designed and fabricated. The measured phase noise of the dual-band oscillator is dBc/Hz and dBc/Hz at 100 kHz offset from 4.18 and 5.49 GHz oscillation frequencies, which correspond to the figure-of-merit (FOM) of 188.7 and 189.1 dBc/Hz, respectively. The second-order and third-order intermodulation products of the two oscillation signals are suppressed to below dBc, as compared to the 4.18 GHz signal.Index Terms-Complementary split-ring resonator (CSRR), diplexer, dual-band, oscillator, SIW.
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