Substrate Integrated Waveguide Slot Antenna Research Articles

A novel design of modified I-shaped low profile broadband cavity-backed SIW slot antenna

This article proposes a novel procedure to enhance the bandwidth of substrate-integrated waveguide (SIW) slotted antennas. By introducing a rectangular slot on the cavity's bottom surface, the TE210 cavity mode is perturbed, leading to the successful generation and merging of odd and even TE210 modes. This approach achieves an impedance bandwidth of 13.5%. To further enhance the bandwidth, the rectangular slot is modified into an I-shaped slot by adding vertical slits at each end, increasing the impedance bandwidth to 15.1%. Placing the modified I-shaped slot on the ground plane further enhances the impedance bandwidth to 17.2%. The constructed antenna maintains a gain of 7.83 dBi at 10.2 GHz and 7.85 dBi at 11.4 GHz, with a measured impedance bandwidth of 19.04%. The design retains several advantageous features, including lightweight construction, easy fabrication, and seamless integration.

Enabling Wide Bandwidth in Substrate-Integrated Waveguide Slot Antennas by Using Low-Index Metamaterials

Enabling Wide Bandwidth in Substrate-Integrated Waveguide Slot Antennas by Using Low-Index Metamaterials

A dual‐band dual‐polarized shared‐aperture SIW slot antenna array with beam scanning

AbstractThis letter proposes a low‐profile dual‐band dual‐polarized (DBDP) substrate‐integrated waveguide (SIW) slot antenna array with beam scanning. By stacking the SIW transverse slot array (TSA) above the longitudinal slot array (LSA) in one aperture, two orthogonal polarizations are generated at two bands. To avoid the radiation slots of the LSA and the TSA from overlapping, the LSA is developed based on the proposed LSA unit whose collinear‐slot arrangement is realized by introducing metallized vias. Two planar parabolic reflectors based linear source generators (LSGs) are integrated to feed the shared‐aperture radiation array. By moving two independent SIW horns, the proposed antenna can obtain the steering angles of ±34° and ±27° at the central frequencies of 11.2 and 13 GHz, respectively. Two beams with orthogonal polarizations scan in the same plane. The simulated results have been validated by the experimental ones. The proposed antenna has low profile and is a potential candidate for satellite and wireless communications.

Electrothermal Design of SIW Slot Antenna Array With Fin-Shaped Heatsink Enclosed

In this article, an electrothermal co-design of substrate integrated waveguide (SIW) slot antenna array combined with fin-shaped heatsink is proposed. The antenna array is constructed by 4 <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\times8$ </tex-math></inline-formula> SIW slot elements. The heatsink structure above the antenna array not only improves the radiation performance of the antenna array but also enhances the electromagnetic compatibility (EMC) and the heat dissipation capability of the whole structure. The measured realized gains over the operating frequency range increase from 15.4–18.1 to 16.1–19.7 dBi when the heatsink is mounted on the antenna array. Meanwhile, the enclosed heatsink reduces the hotspot temperature rise of the system by 57%. The measured results are in good agreement with the simulated ones.

A novel single layer SIW 6 × 6 beamforming network for 5G applications

A novel single layer 6 × 6 beamforming network (BFN) based on substrate integrated waveguide (SIW) is proposed for 5G applications. The proposed BFN is realized by 3 × 3 multi-aperture couplers (MACs), hybrid couplers, phase shifters, and crossovers. The BFN is designed for equal power division and ± 30°, ± 90°, ± 150° phase difference between output signals in the 28–32 GHz frequency band. By feeding a 6 × 2 SIW slot antenna array with proposed BFN, a six-beam antenna is implemented that generates six symmetrical beams in the ± 11°, ± 31°, and ± 52° directions. To confirm the simulation results, the proposed six-beam antenna is fabricated and measured. The simulation and measurement results show that the six-beam antenna has good radiation patterns, −10 dB impedance bandwidth from 28 GHz to 32 GHz, and a 3-dB wide-angle coverage of about 150°. The size of the antenna is 106 × 31.8 × 0.787 mm3, which is suitable for 5G applications.

A Low-Sidelobe Circularly Polarized Continuous Beam-Scanning Array Using Double-Layer Rotated Structure for Ku-Band Satellite Communications

In this letter, a low-sidelobe level (SLL) circularly polarized (CP) beam-scanning array antenna based on a double-layer rotated structure is proposed for <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">Ku</i> -band satellite communications. It is comprised of a 16 × 24 CP substrate integrated waveguide slot antenna array and a rotatable feeding network. Detailed design methodology and working mechanism of the proposed antenna array are presented and analyzed, in particular, the method of achieving low SLL in Blass matrix design. A prototype was fabricated and measured, and the measured results indicate that an AR < 1.5 dB and a max SLL suppression of 19.4 dB at 11.95 GHz can be achieved. Its superiorities of low profile, low SLL, high gain, and continuous beam-scanning ability make the proposed array antenna a promising candidate for satellite communications.

Dielectric rod loaded tunable substrate integrated waveguide slot antenna

This paper presents a novel passive tuning technique to mechanically tune the resonant frequency of a substrate integrated waveguide (SIW) slot antenna, by using cylindrical rods of different dielectric materials in the air holes. A full-wave 3-dimensional Electromagnetic simulator software is used to estimate tunability in the resonant frequency of the SIW slot antenna, which is then analysed using its equivalent circuit, and then verified experimentally. Tunability is obtained by changing relative permittivity of dielectric rods. Measurements show good frequency tunability even with a limited number of dielectric rods and gains over 5 dBi. The similarity in the radiation patterns with tuning, demonstrates a good characteristic for tunable antennas. The technique is simple but effective and does not require external direct current bias circuitry, which removes parasitic effects and less power consumption. The low field perturbation of dielectric rods provides better loss performance and a higher Q-factor over a wider bandwidth. The initial design demonstrates a cost-effective tuning technique achieving return loss (>10 dB) in the X-band. This technique is also suitable for practically overcoming the performance deviation due to fabrication inaccuracies and temperature variation.

Octa-OAM-mode SIW slot antenna on two PCB layers with simple feeding networks

ABSTRACT This paper demonstrates the design and simulation analysis in association with fabrication measured results of an orbital angular momentum (OAM) substrate integrated waveguide (SIW) slot antenna working at 10 GHz in X band. Simple feeding networks including 90° hybrid couplers are introduced to excite traveling waves inside four separated circular resonators radiating eight OAM modes beams. The antenna is composed of two PCB layers where the circular resonators and feeding networks are located, respectively. The measured results including S-parameters and radiation patterns are in good agreement with the simulation results in HFSS.

A Generalized Flat-Topped Beam Synthesis Approach for Uniform Linear Array With Arbitrary Beam Directions

A systematic approach to synthesize the flat-topped beam (FTB) with arbitrary beam directions for uniform linear arrays (ULAs) is proposed, illustrated, and demonstrated. Based on the correspondence between the far-field pattern of ULAs and the response function of finite impulse response (FIR) filters, both the broadside and end-fire FTBs can be synthesized using window method, whereas the oblique FTB synthesis is failed due to the appearance of grating lobes. A mathematical analyzation indicates that two grating lobes are conjugate to each other. Thus, a linear phase method (LPM) is proposed to apply progressive excitation phases to each individual array element, which can eliminate the grating lobes by manipulating the two conjugate beams to overlap with each other. The proposed LPM is generalized to the synthesis of broadside, oblique and unidirectional end-fire FTBs, and the corresponding inter-element spacing constraints are addressed. The proposed approach is experimentally verified using a 16-element substrate-integrated waveguide slot antenna array. Comparing with the conventional Fourier series method and Woodward-Lawson method, the proposed approach has advantages of both smaller ripples in the main beam and controllable side-lobe levels. The proposed approach is promising for offering efficient beamforming functionalities for wireless communications, imaging, and radar applications.

C/X Dual-Band Circularly Polarized Shared-Aperture Antenna

A novel dual-band circularly polarized (CP) shared-aperture antenna is proposed in this letter. The overall structure consists of a substrate-integrated waveguide (SIW) slot antenna working in the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -band, which also serves as the top patch of a <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> -band microstrip-like antenna. The SIW slot antenna achieves CP radiation by etching a circular slot on the top surface of a dual-mode SIW cavity. The patch antenna realizes CP radiation by loading two pairs of asymmetric shorting vias. With this design method, the proposed antenna can achieve dual-band CP operation and high aperture reuse efficiency. Besides, the feeding pin of the SIW slot antenna inserts through one of the asymmetric shorting vias, that is, the shorting vias serves as both perturbations for the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">C</i> -band operation and a feeding path for the <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">X</i> -band operation. This new feeding scheme can prevent signal crosstalk between the two bands.

Efficient SIW-Feed Network Suppressing Mutual Coupling of Slot Antenna Array

In this communication, an effective method to suppress mutual coupling between two substrate-integrated waveguide (SIW) slot antenna arrays is presented. To achieve that, a decoupling feed network is used. The feed network is composed of a two-layer directional coupler that is connected to two SIW-slot antenna arrays directly to establish an indirect coupling with controlled magnitude and phase, which can effectively reduce the direct coupling generated by surface waves between the array elements. A 2 ×4 array of slot antenna as well as the proposed decoupling network is designed, fabricated, and measured to illustrate the effectiveness of the proposed technique. The measured and simulated results verified the good decoupling performance. The measured mutual coupling is about -35 dB at the center frequency without negatively affecting the return loss and radiation patterns. The proposed mechanism of the decoupling network is simple and successfully used in SIW slot antenna arrays.

A Dual-Layer Filtering SIW Slot Antenna Utilizing Double Slot Coupling Scheme

This letter presents a filtering substrate integrated waveguide slot antenna design with multiple radiation nulls based on a double slot coupling scheme. It consists of a dual-layer cavity resonator, a slot in the first layer, and two coupling slots inserted in the middle layer. The slot in the first layer functions as the antenna radiator. This radiator is etched in the first cavity instead of the last stage of the network, resulting in two radiation nulls. A double slot coupling scheme is employed in the middle layer to not only couple the two-layer cavity resonators but also generate two more radiation nulls. Owing to these radiation nulls, the antenna features high-frequency selectivity as well as out-of-band radiation suppression level. For demonstration, the proposed filtering antenna is implemented and tested. The antenna operates at the center frequency 4.5 GHz with 15.4% (4.2-4.9 GHz) measured bandwidth. The maximum gain within the operating band is 7.5 dBi and four radiation nulls are generated. Better than 21 dB out-of-band radiation rejection level is obtained.

Dual-Band Structure-Shared Antenna With Large Frequency Ratio for 5G Communication Applications

A dual-band structure-shared antenna with large frequency ratio is proposed in this letter by integrating two substrate integrated waveguide slot antennas (SIWAs) on the branches of dipole. In the proposed structure, dipole is fed by coaxial connector while SIWAs are fed by two microstrip lines. To improve the stability of the dipole and the isolation among three antennas, microstrip high-pass filter is introduced. Measured results show that the proposed antenna works at 27.3−28.8 GHz with directional radiation pattern and 3.02−5.03 GHz with omnidirectional radiation pattern.

Differential SIW slot antenna array with intrinsic common‐mode rejection

In this study, the differential substrate integrated waveguide (SIW) slot antenna array is proposed with intrinsic common-mode (CM) rejection. Through field analysis, it is found that the SIW is a natural differential transmission line which can only transmit differential signal due to the characteristics of hybrid electromagnetic boundary perfect electrical conductor and perfect magnetic conductor. Hence, it can also be seen as a natural balun with intrinsic CM suppression. Thus, a compact 1 × 4 differential SIW slot antenna array with high CM rejection can be designed using the differential microstrip transition structure which has little conversion between differential-mode (DM) and CM. For the design of differential SIW passive device, the DM equivalent half circuit is a single-ended SIW device with height halved. Further, the 4 × 4 differential SIW antenna array with high CM rejection can be designed with a T-shaped differential SIW four-way power divider. The 1 × 4 and 4 × 4 differential SIW antenna arrays are fabricated and good agreements between the simulated and measured results demonstrate the validity of proposed configurations.

Performance of a New Design Based on Substrate-Integrated Waveguide Slotted Antenna Arrays for Dual-Band Applications (Ku / K)

This paper introduces and discusses the study of a new concept for SIW array antenna development. This conducted development is based on three designs, two of them related to 1x2 arrays fed by SIW line, combined with SIW inset line, and the last designed for 2X2 array antenna feed by SIW inset line. All these structures are designed to give dual-band at (Ku - K) bands with enhanced gain and bandwidth. The new 2x2 array antenna has a high gain, and it consists of four SIW cavities staggered patches with a 90° phase shift, which are fed using microstrip line shielded by SIW vias. The designs were conducted using full-wave simulator ANSYS HFSS - the frequency domain solver. The 2x2 array antenna gives a return loss about (-20 dB), a high gain of 9.05 dB, and two bandwidth equals 210 MHz and 1310 MHz respectively at both of the operating bands. To validate the simulated results the simulation was conducted again using the time-domain solver of the CST Microwave Studio (MWS) full-wave simulator. Simulation results obtained from the two software having different solvers were in good agreement in the results.

Design of Coplanar Slotted SIW Antenna Arrays for Beam-Tilting and 5G Applications

A new solution for feeding the engraved slot antennas based on the substrate integrated waveguide (SIW) technology is presented in this letter. The structure is designed to operate at 25 GHz for beam-tilting and fifth-generation applications. Here several passive SIW slot antennas are proposed to cover an area from −56° to +56° with an offset of 10° at the operating frequency without using any phased shifter, in order to limit the losses. This new feeding approach is developed by using associated SIW holes to excite differently the centered slots located on the SIW structure broad face via coplanar lines. The electrical phase shifts are controlled by the position and number (one or two) of coplanar lines, and the combined slot configurations achieve beam-tilting function.

420-GHz terahertz SIW slot antenna with quartz superstrates in silicon technology

To meet the needs of terahertz imaging and communication, a 420-GHz on-chip antenna (OCA) with high gain and high radiation efficiency is designed using a standard 55 nm CMOS technology. In the proposed OCA structure, the substrate integrated waveguide (SIW) antenna forms a back cavity to suppress the surface waves and separate the radiation aperture from the low-resistivity substrate. To increase the efficiency of OCA, a single-layer quartz superstrate is proposed. An analytical model to calculate the radiation efficiency is presented, and a detailed design approach is described. The proposed antenna is simulated using Ansoft HFSS. The simulated antenna has a maximum gain of 4.9 dBi and a radiation efficiency of 76.27%. The bandwidth of S11 below −10 dB is 44 GHz. The OCA has good performance and can be widely used in terahertz imaging and communication.

5G beam-steering 2×2 butler matrix with slotted waveguide antenna array

In this research paper, substrate integrated waveguide (SIW) was proposed as a technique by realizing bilateral edge walls to produce a compact 5G beam-steering antenna at 24 GHz. The beam forming network is produced using SIW directional coupler perform as 2×2 Butler Matrix (BM) fed with SIW slotted waveguide antenna array. The output signal is steered from -29 degrees and +29 degrees when the signal is fed to the respective input ports. If one of the input ports is fed, the signal is evenly distributed between the adjacent output ports with 90 degree constant phase shift. The compact size of directional coupler was designed by longitude slots on the surface of SIW substrate with bandwith of 16.85% at the operating frequency. The proposed antenna produce gain of 6.34 dB at operating frequency and the promising outcome of the beam steering make proposed design suitable for 5G communications especially with tracking capabilities.

Ka-Band 8 × 8 Low-Sidelobe Slot Antenna Array Using a 1-to-64 High-Efficiency Network Designed by New Printed RGW Technology

This letter proposes an 8 × 8 high-efficiency low-sidelobe slot antenna array operating at Ka -band frequencies with a feeding network designed by a new printed ridge gap waveguide (PRGW). The device consists of a slot antenna element, a PRGW unequal feeding network, and a stripline-to-PRGW transition. The substrate integrated waveguide slot antenna element fed by the PRGW through a coupling aperture has a wide bandwidth, and the isolation is also increased by adding metallized holes to the array. Compared with other gap waveguide antenna arrays, our work realizes an antenna element fed separately due to the use of a PRGW with a compact mushroom cell size, which helps improve the properties of the unequal feeding network. In addition, the transition between the PRGW and stripline is also designed with a wide band and low insertion loss. The measured reflection coefficient is less than –10 dB over a 6 GHz bandwidth (16%), the gain is more than 23.5 dBi in the working band, and the sidelobe level is –18 dB. In addition, the measured radiation efficiency of the array with a two-dimensional Taylor distribution is 41.69%.

Design of a Low-SLL SIW Slot Array Antenna With a Large Declination in $Ka$ -Band

A small-size large-declination longitudinal slot array antenna based on substrate integrated waveguide (SIW) technology was proposed. Compared with the conventional SIW slot array, the proposed antenna achieves a larger declination and a lower SLL. The antenna is mainly composed of three parts, a dielectric substrate, a coaxial port, and a matched load. The antenna contains 13 radiation slots, and the adjacent slot spacing is greater than half of the waveguide wavelength, so the main beam is biased towards the load. To achieve low sidelobe levels (SLL), the amplitude distribution of the 13 slots is based on Taylor synthesis of SLL = -25 dB. The antenna was processed and measured. From the measured results, the antenna achieved a beam declination of 26° and a SLL below -20 dB from 35.2 to 35.8 GHz. With the same number of slots, the length of the slot array of the SIW structure is only 44.8% of the length of the standard metal hollow waveguide. Based on the performance achieved, the SIW slot antenna is an excellent candidate for carrier conformal and large declination applications.