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

Single fed low profile cavity backed crossed slot antennas for dual frequency dual linear polarization and circular polarization applications are first presented in this paper. By employing the substrate integrated waveguide (SIW) technique in the antenna designs, the low profile backed cavity structure can be realized by using only a single layer of low cost printed circuit board (PCB) substrate. A single grounded coplanar waveguide (GCPW) is employed as the feeding element to excite the TE 120 and TE 210 modes in the SIW cavity. A crossed slot structure is used as the radiating element in order to radiate the desired dual linearly or circularly polarized wave. From the measurement results, it is seen that these novel antennas retain the advantages of conventional metallic cavity backed antennas, including high gain, high front-to-back ratio (FTBR), and low cross polarization level (CPL). Furthermore, the proposed antennas also possess the advantages of low profile, light weight, low fabrication cost, and easy integration with planar circuits.

Development of Low Profile Cavity Backed Crossed Slot Antennas for Planar Integration

A bandwidth enhanced method of a low-profile substrate integrated waveguide (SIW) cavity-backed slot antenna is presented in this paper. Bandwidth enhancement is achieved by simultaneously exciting two hybrid modes in the SIW-backed cavity and merging them within the required frequency range. These two hybrid modes, whose dominant fields are located in different half parts of the SIW cavity, are two different combinations of the and resonances. This design method has been validated by experiments. Compared with those of a previously presented SIW cavity-backed slot antenna, fractional impedance bandwidth of the proposed antenna is enhanced from 1.4% to 6.3%, its gain and radiation efficiency are also slightly improved to 6.0 dBi and 90%, and its SIW cavity size is reduced about 30%. The proposed antenna exhibits low cross polarization level and high front to back ratio. It still retains advantages of low-profile, low fabrication cost, and easy integration with planar circuits.

Bandwidth-Enhanced Low-Profile Cavity-Backed Slot Antenna by Using Hybrid SIW Cavity Modes

A novel wearable dual-band textile antenna, designed for optimal on-body performance in the 2.4 and 5.8 GHz Industrial, Scientific and Medical bands, is proposed. By using brass eye-lets and a combination of conducting and non-conductive textile materials, a half-mode substrate integrated waveguide cavity with ground plane is realized that is very compact and flexible, while still directing radiation away from the wearer. Additional miniaturization is achieved by adding a row of shorting vias and slots. Beside excellent free space performance in the 2.4 and 5.8 GHz bands, respectively, with measured impedance bandwidth of 4.9% and 5.1%, maximal measured free-space gain of 4.1 and 5.8 dBi, and efficiency of 72.8% and 85.6%, very stable on-body performance is obtained, with minimal frequency detuning when deploying the antenna on the human body and when bent around cylinders with radii of 75 and 40 mm. At 2.45 and 5.8 GHz, respectively, the measured on-body gain is 4.4 and 5.7 dBi, with sufficiently small calculated SAR values of 0.55 and 0.90 W/kg. These properties make the proposed antenna excellently suited for wearable on-body systems.

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Compact Half Diamond Dual-Band Textile HMSIW On-Body Antenna

A quarter-mode substrate integrated waveguide (QMSIW) which is the quadrant sector of a square waveguide resonator is proposed and investigated in this paper. The QMSIW is realized by bisecting the half-mode substrate integrated waveguide (HMSIW) into two parts along the fictitious quasi-magnetic wall when it operates with TE101 and TE202 modes as the way bisecting the substrate integrated waveguide (SIW) to HMSIW. The QMSIW can almost preserve the field distribution of original SIW and leaky wave is achieved from the dielectric aperture of the QMSIW. When the feeding port is placed at one corner of the QMSIW, a linearly polarized radiation is obtained when the QMSIW resonates in TE101QM mode, and when the QMSIW resonates in TE202QM mode, a circularly polarized (CP) wave is achieved. An antenna is designed, fabricated, and measured based on the proposed QMSIW. The measurement results match with the simulation results very well.

Quarter-Mode Substrate Integrated Waveguide and Its Application to Antennas Design

A novel design method of low profile cavity backed planar slot antenna has been described in this paper. The whole antenna including backed cavity and feeding element is completely constructed at a single substrate by using substrate integrated waveguide technique and grounded coplanar waveguide. An example with 1.7% bandwidth has been presented, which has 5.4 dBi gain, 16.1 dB front-to-back ratio and -19 dB maximum cross polarized radiation level with its total thickness less than lambda0/50. The proposed antenna keeps good radiation performance of conventional cavity backed antenna and has advantages of conventional planar antenna including low profile, light weight, easy fabrication with low cost and convenient integration with planar circuit.

Planar Slot Antenna Backed by Substrate Integrated Waveguide Cavity

The concept of a novel single probe feed cavity backed circularly polarized antenna based on substrate integrated waveguide technique has been investigated in this article. The proposed antenna provides high circularly polarized radiation performance and keeps advantages of low profile and convenient fabrication. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2996–2998, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23848

Single probe fed cavity backed circularly polarized antenna

A gain enhanced method of substrate integrated waveguide (SIW) cavity backed slot antenna by using a high order cavity resonance has been presented in this paper. When the TE220 resonance is excited in the SIW cavity, a high gain radiation with the gain of 8.1 dBi can be achieved, which is about 2.7 dB higher than that of the previously presented SIW cavity backed slot antenna by using the TE120 or TE210 resonance. This design method can be extended to using the higher order cavity resonances such as TE230, TE330 and TE440 etc. to get a much higher gain radiation. Compared with an antenna array which has the same gain, the proposed antenna has advantages of simple feed network and more compact size.

A Gain Enhanced Cavity Backed Slot Antenna using High Order Cavity Resonance

A simple method of gain improvement for the cavity backed slot antenna based on the substrate integrated waveguide technique has been presented in this article. By using dual slot at the cavity edges to substitute a single slot at the cavity center as the radiating element, gain of the cavity backed slot antenna has been improved about 1.7 dB whereas its total size is little reduced. The proposed antenna has high radiation performance and keeps the advantages low profile, easy integration, and low cost fabrication. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:2767–2769, 2010; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25582

Cavity backed dual slot antenna for gain improvement

A novel planar low-profile cavity-backed slot antenna for circularly polarized applications is presented in this paper. The low-profile substrate integrated waveguide (SIW) cavity is constructed on a single PCB substrate with two metal layers on the top and the bottom surfaces and metallized via array through the substrate. The SIW cavity is fed by a SIW transmission line. The two orthogonal degenerate cavities resonance TM110 mode are successfully stimulated and separated. The circularly polarized radiation has been generated from the crossed-slot structure whose two arms’ lengths have slight difference Its gain is higher than 5.4 dBi, the peak cross-polarization level is lower than −22 dB, and the maximum axial ratio (AR) is about −1.5 dB. Compared with the previous presented low-profile cavity-backed slot antenna work, the spurious radiation from the proposed antenna’s feeding element is very low and it has less interference on the following circuits.

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Lin Xi Dong

Papers

Planar Slot Antenna Backed by Substrate Integrated Waveguide Cavity

Single probe fed cavity backed circularly polarized antenna

A Gain Enhanced Cavity Backed Slot Antenna using High Order Cavity Resonance

Cavity backed dual slot antenna for gain improvement

Substrate Integrated Waveguide Fed Cavity Backed Slot Antenna for Circularly Polarized Application