This work proposes a broadband transition from tapered microstrip line-to-substrate-integrated waveguide (SIW) using parallel half-mode SIW (HMSIW) for C/X-band applications. The proposed transition comprises four sections: a microstrip feed, tapered microstrip line, tapered parallel HMSIWs, and a waveguide section (SIW). Placing the parallel HMSIWs section between the tapered microstrip line section and the SIW part improves the S-parameters characteristics of the near-cut-off frequency. The HMSIWs section has a lower cut-off frequency than the SIW part, about 4.6 GHz. The lower cut-off- frequency is obtained by gradually altering the electromagnetic field mode to reduce reflection. Which helps convert from TEM mode to TM conversion. The proposed transition is designed, simulated, fabricated, and experimentally verified in order to compare between simulated and experimental results. For the back-to-back laboratory prototype of the transition, the experimental return loss results are less than 20 dB in the 4.6 to 11 GHz frequency range. At the same time, the measured minimum insertion loss is lower than 0.37 dB (maximum: 1.51 dB).

The concept of the corrugated via-wall substrate-integrated waveguide (CV-WSIW) reported by the same authors earlier has now been extended to the mm-wave frequency range, and the transitions for this category of SIWs from microstrip line (ML) are presented in this work. A new design of enhanced CV-WSIW for 18-40 GHz frequency range is proposed. The design includes a tapered section of the microstrip line and two rows of metallic vias with the gap between them. They are providing a better impedance match and reduced overall loss. The proposed design offers improved performance in terms of broadband, return loss (RL), insertion loss (IL), and total loss (TL). The laboratory prototypes are developed, and the obtained simulation results show a close agreement with the measured results. The experimental results show the minimum RL of 22dB, IL of 0.22-0.42dB, a fractional bandwidth of 75.80%, a figure-of-merit of 967.9, and the TL below 20% for ML/CV-WSIW transition within 18-40GHz range. Three additional ML/CV-WSIW transitions were also designed and tested, so that four tested transitions cover 8-60GHz range; an additional fifth transition was simulated only in 60-140GHz range.

The efficacy of a reconfigurable intelligent surface (RIS)-aided network for enhanced connectivity in skip zones is demonstrated through real-time video streaming. The demonstration is carried out with the help of National Instruments universal software radio peripheral (NI-USRP) devices integrated with an RIS prototype. The RIS prototype is designed and fabricated using a 16 × 10 metasurface operating at 5.3 GHz carrier frequency. Utilizing LabVIEW’s long-term evolution (LTE) application framework module, good connectivity between the transmitter and receiver in an otherwise skip zone is exhibited. Various modulation and coding schemes have been applied to the streamed data to observe the throughput, SINR, and constellation diagrams with respect to different positions of the receiver in the non-line of sight (NLOS) skip zone. The demonstration ratifies the potential of RIS system in practical applications related to future wireless communications.

This paper proposes the Corrugated Via-Wall Substrate Integrated Waveguide (CVWSIW) (with enhanced performance compared to the traditional SIW) and the transitions to this newly proposed CVWSIW from a conductor-backed coplanar waveguide (CB-CPW). The CB-CPW slot lines and the gap between two metallic via rows play a prominent role in widening the bandwidth and reducing the loss. The CB-CPW-CVWSIW transition is initially designed in the 4–8 GHz (C-band) range. Following the same design procedure, the transitions are made for other five different bands to cover the frequencies from 2 to 40 GHz. Improved performance in terms of bandwidth, insertion loss, and total loss is the benefit of the designed transitions with the proposed CVWSIW. Laboratory prototypes of the transitions are fabricated and experimentally measured to cross verify the simulation results. The measured results show, for example, the minimum return loss of 15 dB, maximum insertion loss of 0.36 dB, and fractional bandwidth of 62.16% for C-band.