Design Of Wideband Antenna And Miniaturized Filter Based On Ridge Substrate Integrated Waveguide

Substrate integrated waveguide(SIW)is a novel planar transmission line,which can be regarded as a traditional rectangular waveguide(RW)in substrate form,and permits the design of low-cost,low-loss,high-power capability,and high-density integration components and interconnects.However,conventional RF front-end components based on SIW are difficult to satisfy the broadband and miniaturized requirements of microwave,mm-wave systems.Ridge substrate integrated waveguide(RSIW)is a novel waveguide structure based on SIW,which inherits many advantages of SIW and has a compact structure and wider single-mode transmission bandwidth,so it is widely used in microwave or millimeter-wave circuits.For research on miniaturization and wideband of antenna and filter based on RSIW,the work of this paper is as follows:Firstly,a printed antipodal Vivaldi antenna(AVA)fed with double ridged substrate integrated waveguide(DRSIW)is proposed in this paper.DRSIW can achieve a much lower cut-off frequency compared with normal SIW because of inserted ridge.As the printed AVA has intrinsically wide bandwidth,the DRSIW fed printed AVA realizes a significantly decreased cut-off frequency and increased bandwidth compared with Vivaldi antennas fed by normal SIW.Consequently,the electrical dimensions at the cut-off frequency of the AVA fed by DRSIW are smaller than the AVA fed by normal SIW,and the miniaturization of the AVA is successfully realized.To verify the feasibility of the proposed design,a prototype of a DRSIW fed printed AVA is fabricated and measured.The bandwidth with|S₁₁|?-10 d B ranges from 11.02 GHz to 40 GHz,covering Ku,K and Ka bands.The gains are 2.15-5.75 d B within the operating band.The results show that the bandwidth and miniaturization of the printed antipodal Vivaldi antenna has been successfully increased by using the feed of DRSIW.Secondly,a novel dual-mode ridged substrate integrated waveguide cavity resonator and a series of dual-band RSIW filter with miniaturized dimension and independently controllable resonant frequencies is proposed.The resonator realized by two stacked dielectric substrates configurationally consists of a SIW cavity and a shorted metallic ridge in the form of a rectangular patch inside.The SIW cavity is encircled by metallic vias connecting through top and bottom substrates,and the ridged patch connected with five shorting vias and etched with four slots is designed on the upper surface of the bottom substrate.Attributed to the ridge structure,the resonant frequencies of the TE₁₁₀ and TE₁₂₀modes of the cavity are lowered by 46%and 18%compared with the conventional design without the ridge.The resonant frequencies of the two modes can be adjusted independently and flexibly by two adjusting vias and the slotted ridge patch.A series of dual-band bandpass filters(BPFs)are designed to verify the feasibility of the proposed RSIW resonators,and a third-order BPF is fabricated and measured.The measured results show two passbands centered at 15.48 and 27.30 GHz with 3-d B-S₂₁ bandwidths of 6.2%and 5.1%are obtained,confirming the proposed dual-band RSIW filter successfully achieves 62%size reduction compared with the conventional SIW filter without the ridge.