Substrate-integrated waveguide (SIW) technology represents an emerging and very promising candidate for the development of circuits and components operating in the microwave and millimetre-wave region. SIW structures are generally fabricated by using two rows of conducting cylinders or slots embedded in a dielectric substrate that connects two parallel metal plates, and permit the implementation of classical rectangular waveguide components in planar form, along with printed circuitry, active devices and antennas. This study aims to provide an overview of the recent advances in the modelling, design and technological implementation of SIW structures and components.

Review of substrate-integrated waveguide circuits and antennas

A new generation of high-frequency integrated circuits is presented, which is called substrate integrated circuits (SICs). Current state-of-the-art of circuit design and implementation platforms based on this new concept are reviewed and discussed in detail. Different possibilities and numerous advantages of the SICs are shown for microwave, millimeter-wave and optoelectronics applications. Practical examples are illustrated with theoretical and experimental results for substrate integrated waveguide (SIW), substrate integrated slab waveguide (SISW) and substrate integrated nonradiating dielectric (SINRD) guide circuits. Future research and development trends are also discussed with reference to low-cost innovative design of millimeter-wave and optoelectronic integrated circuits.

The substrate integrated circuits - a new concept for high-frequency electronics and optoelectronics

Phononic crystals are the acoustic wave analogue of photonic crystals. Here a periodic array of scattering inclusions located in a homogeneous host material forbids certain ranges of acoustic frequencies from existence within the crystal, thus creating what are known as acoustic bandgaps. The majority of previously reported phononic crystal devices have been constructed by hand, assembling scattering inclusions in a viscoelastic medium, predominantly air, water or epoxy, resulting in large structures limited to frequencies below 1 MHz. Recently, phononic crystals and devices have been scaled to VHF (30–300 MHz) frequencies and beyond by utilizing microfabrication and micromachining technologies. This paper reviews recent developments in the area of micro-phononic crystals including design techniques, material considerations, microfabrication processes, characterization methods and reported device structures. Micro-phononic crystal devices realized in low-loss solid materials are emphasized along with their potential application in radio frequency communications and acoustic imaging for medical ultrasound and nondestructive testing. The reported advances in batch micro-phononic crystal fabrication and simplified testing promise not only the deployment of phononic crystals in a number of commercial applications but also greater experimentation on a wide variety of phononic crystal structures.

https://iopscience.iop.org/article/10.1088/0957-0233/20/1/012002/pdf

Microfabricated phononic crystal devices and applications

Because of the low dimensional power of its force scaling law, surface tension is appropriate for carrying out reshaping and assembly in the microstructure size domain. This paper reviews work on surface tension powered self-assembly of microstructures. The existing theoretical approaches for rotational assembly are unified. The demonstrated fabrication processes are compared. Mechanisms for accurately determining the assembled shape are discussed, and the limits on accuracy and structural distortion are considered. Applications in optics, electronics and mechanics are described. More complex operations (including the combination of self-assembly and self-organization) are also reviewed.

Surface tension-powered self-assembly of microstructures - the state-of-the-art

The propagation properties of the half-mode substrate integrated waveguide (HMSIW) are studied theoretically and experimentally in this paper. Two equivalent models of the HMSIW are introduced. With the first model, equations are derived to approximate the field distribution inside and outside the HMSIW. Using the second model, an approximate closed-form expression is deduced for calculating the equivalent width of an HMSIW that takes into account the effect of the fringing fields. The obtained design formulas are validated by simulations and experiments. Furthermore, the attenuation characteristics of the HMSIW are studied using the multiline method in the frequency range of 20-60 GHz. A numerical investigation is carried out to distinguish between the contributions of the conductive, dielectric, and radiation losses. As a validation, the measured attenuation constant of a fabricated HMSIW prototype is presented and compared with that of a microstrip (MS) line and a substrate integrated waveguide (SIW). The SIW is designed with the same cutoff frequency and fabricated on the same substrate as the HMSIW. The experimental results show that the HMSIW can be less lossy than the MS line and the SIW at frequencies above 40 GHz.

/pdf/characterization-of-the-propagation-properties-of-the-half-jv82wmu7p5.pdf

Characterization of the Propagation Properties of the Half-Mode Substrate Integrated Waveguide

A substrate integrated folded waveguide (SIFW), integrated transition to shielded stripline and a SIFW filter are demonstrated and shown to be in good agreement with X band measurements. Both the filter and waveguide are considerably smaller than their unfolded counterparts. Furthermore, the filter response is defined purely in terms of a photolithographically etched plane.

Substrate integrated folded waveguides (SIFW) and filters

This paper presents the design and fabrication of substrate-integrated waveguides and filters for use at millimeter-wave frequencies. The components described are fabricated using photoimageable thick-film materials. Measurements on V- and W-band waveguide-to-microstrip transitions are presented. Losses resulting from the reduced-height nature of the waveguides are extracted from thru-relect-line calibration standards illustrating the effect of current losses in the broadwalls of the waveguides. The design of fourth-order 0.01-dB ripple Chebyshev resonant cavity filters operating at V-, W-, D-, and G-band is presented. The measured results of all components are in excellent agreement with simulated predictions.

Millimeter-wave substrate integrated waveguides and filters in photoimageable thick-film technology

This communication presents a single-feed ultra-wideband circularly polarized (CP) antenna with high front-to-back ratio (FBR). The antenna is composed of two orthogonally placed elliptical dipoles printed on both sides of a substrate. To realize high FBR, a novel composite cavity is also proposed and integrated with the presented crossed dipoles, which effectively reduces the backlobe of the crossed dipoles. Simulation results are in good agreement with the measured results that demonstrate an impedance bandwidth from 0.9 to 2.95 GHz (106.5%) and a 3-dB axial ratio (AR) bandwidth from 1 to 2.87 GHz (96.6%). The measured FBR is about 30 dB across the whole global navigation satellite system (GNSS) band. Compared with other reported single-feed wideband CP antennas, the antenna has advantages such as a wider CP bandwidth and lower backlobe radiation.

/pdf/single-feed-ultra-wideband-circularly-polarized-antenna-with-gsuv10auho.pdf

Single-Feed Ultra-Wideband Circularly Polarized Antenna With Enhanced Front-to-Back Ratio

The paper presents a new concept in antenna design, whereby a photo-imageable thick-film process is used to integrate a waveguide antenna within a multilayer structure. This has yielded a very compact, high performance antenna working at high millimeter-wave (mm-wave) frequencies, with a high degree of repeatability and reliability in antenna construction. Theoretical and experimental results for 70 GHz mm-wave integrated antennas, fabricated using the new technique, are presented. The antennas were formed from miniature slotted waveguide arrays using up to 18 layers of photo-imageable material. To enhance the electrical performance a novel folded waveguide array was also investigated. The fabrication process is analyzed in detail and the critical issues involved in the fabrication cycle are discussed. The losses in the substrate integrated waveguide have been calculated. The performance of the new integrated antenna is compared to conventional metallic, air-filled waveguide antennas, and also to conventional microstrip antenna arrays operating at the same frequencies.

/pdf/millimeter-wave-substrate-integrated-waveguide-antennas-1w98f7rtaw.pdf

Millimeter Wave Substrate Integrated Waveguide Antennas: Design and Fabrication Analysis

Waveguide slot antennas integrated on microwave laminate are presented, and single and dual slot antennas are described, which operate at 10 GHz.

Paul R. Young

Papers

Substrate integrated folded waveguides (SIFW) and filters

Millimeter-wave substrate integrated waveguides and filters in photoimageable thick-film technology

Single-Feed Ultra-Wideband Circularly Polarized Antenna With Enhanced Front-to-Back Ratio

Millimeter Wave Substrate Integrated Waveguide Antennas: Design and Fabrication Analysis

Integrated waveguide slot antennas