Substrate Integrated Waveguide Slot Research Articles

A design of compact wideband substrate integrated waveguide fractal koch surface slot antenna for Ka$$ Ka $$‐band applications

SummaryThis article analyses a substrate integrated waveguide (SIW) fractal koch surface (FKS) slot antenna performance for Ka‐band applications. This FKS slot shape is obtained by modifying the conventional rectangular slot with the first iteration of the FKS method. The resultant FKS slot behaves as a radiator in the provided space. A single‐ and two‐element FKS slotted SIW antenna characteristics are analysed on a 20 mil thick RT/Duroid 5880 substrate and compared with the conventional rectangular slot. The proposed antenna with dimensions mm3 achieves an impedance bandwidth from 27.4 to 32.1 GHz with a fractional bandwidth of 15.79% and achieves a gain of 8.3 dBi in broadside direction by improving space filling factor in SIW structure. The prototype of the SIW‐fed FKS slotted antenna array measurement results is satisfactory with the simulation results.

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

Slotted Substrate-Integrated Waveguide Leaky-Wave Antenna with Improved Backward Scanning Bandwidth and Constant Gain in X-band

An H-shaped slotted leaky-wave antenna (LWA) is proposed based on balanced composite right/left-handed (CRLH) transmission lines (TLs) to improve the backward scanning bandwidth and achieve constant gain. The proposed antenna consists of a substrate-integrated waveguide (SIW) unit cell array configured by an H-shaped slot cut in the top layer of the SIW and a patch embedded beneath the H-shaped slot. The proposed design improves the backward scanning bandwidth compared to planar SIW LWAs. The measured beam radiation is in the range from −79° to 80° over the frequency range of 7.6–12.5 GHz. Moreover, a constant gain of greater than 10 dB is achieved over the entire X-band frequency range.

A Typical Slotted SIW Cavity-backed Antenna for Dual frequency operations in U-NII Bands

A low profile circular shaped cavity-backed substrate integrated waveguide (SIW) antenna with two-typical intersecting rectangular slots on the ground plane is designed to operate in the dominant TM010 mode at a frequency of 5.19 GHz in U-NII-1 band for wireless applications. The initially designed antenna produces a gain of 4 dBi with a narrow impedance bandwidth extending from 5.17 – 5.22 GHz. The antenna design is further modified by insertion of another shifted two-typical intersecting rectangular slots to finally resemble that of Hash shape; resulting in dual band antenna operation at 4.9 and 5.93 GHz. The gains obtained are 3.7 dBi and 1.4 dBi for 4.9 and 5.93 GHz respectively with an impedance bandwidth covering 4.88 - 4.92 GHz and 5.92 – 5.94 GHz respectively. The antenna prototype is fabricated using Arlon AD270 substrate material. Parametric studies are performed in terms of return loss and gain of the antenna. All simulations are carried out using HFSS v19.0 and show similar behavior to their experimentally measured counterparts.

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.

A Singly-Fed Dual-Band Aperture-Sharing SIW Cavity-Backed Slot Antenna With Large Frequency Ratio

A singly-fed dual-band aperture-sharing slot antenna with a large frequency ratio is investigated, based on the substrate integrated waveguide (SIW) technology. The dual-band antenna consists of a rectangular slotted SIW cavity operating at 40 GHz millimeter-wave (MMW) band and a ring slotted SIW cavity operating at 5.2 GHz microwave (MW) band. Due to the self-shielding effect of the SIW cavity, the two radiating elements can be tightly nested with each other, leading to a compact structure with a high ratio of radiating aperture utilization. The MW and MMW SIW radiating elements are fed via a common microstrip line through two separate slots, and they are excited in the hybrid TMh (120, 210) mode and TMh (230, 320) mode respectively. In order to avoid the signal crosstalk, a transverse stub of half-wavelength (in terms of MMW frequency) is added onto the microstrip feed line to prevent the MMW signal from getting into the MW element, while the MMW element can naturally reject the MW signal for its high-pass characteristics. Consequently, good radiation performance is obtained at both the MW and MMW bands, and moreover, the two bands can be independently adjusted.

A Balanced Substrate Integrated Waveguide Phase Shifter with Wideband Common-Mode Suppression

In this paper, a slotted substrate integrated waveguide (SIW) is used to create a balanced phase shifter with wideband common-mode (CM) suppression. Differential-mode (DM) impedance matching and CM suppression are achieved by utilizing the fact that TE20 mode and TE10 (TE30) mode can only transmit DM signals and CM signals, respectively, and by increasing the bandwidth for CM suppression via slots. Furthermore, a wideband phase shift with low phase deviation can be obtained due to the phase slop counteract between the slot and the delay line. Compared with the state-of-the-art, the proposed one has the advantages of wideband CM suppression, wide phase shift range, and a simple and easy-to-make structure. Five prototypes covering the frequency of 3.5 GHz are designed with the relative operating bandwidth for 45° ± 2° (90° ± 4.5°, 135° ± 6°, and 180° ± 8°) phase shifter of 20% (20%, 20%, and 20%), with the minimum insertion loss of 0.41 dB (0.5 dB, 0.58 dB, and 0.59 dB), with the minimum return loss greater than 15 dB, and with the relative bandwidth for 15-dB CM suppression of 59% (59%, 58%, and 57%).

Design of a Low-Cost, Low-Sidelobe-Level, Differential-Fed SIW Slot Array Antenna with Zero Beam Squint

This paper presents a low-cost, low-sidelobe-level, differential-fed, substrate-integrated waveguide (SIW)-based slot array antenna with zero beam squint. The antenna consists of two identical six-way unequal power dividers (PDs) and a 6 × 16 slot array and is realized on a single-layer substrate. The six-way unequal PD provides tapered amplitude and in-phase excitation for six SIWs, and each of them has 16 radiating slots. The 1 × 16 linear slot array on each SIW is excited using a differential feed to avoid undesired beam squinting across its operating band. A two-way hybrid waveguide (WG)-to-SIW E-plane PD is developed to provide equal amplitude and out-of-phase excitation for two six-way unequal power dividers. Moreover, metallic decoupling walls are implemented between two adjacent linear slot arrays to reduce E-plane external mutual coupling. An antenna prototype is fabricated and experimentally verified. The fabricated antenna shows that the measured −10 dB reflection bandwidth is 7.15% (9.57–10.28 GHz), with the achieved gain ranging from 20.30 to 21.92 dBi. A stable boresight beam is observed over the entire operating band. Furthermore, at the designed frequency of 10 GHz, peak SLLs of −29.1 dB and −29.4 dB are achieved in the E- and H-plane, respectively.

Compact low‐cost W‐band large‐scale high‐gain circular‐aperture slot array antenna

Based on substrate-integrated waveguide (SIW) antenna technology, a compact high-gain slot array is proposed in this paper. The proposed antenna is suitable for designing circular aperture and large-scale array in W-band. A method of dividing the array into multiple sections is proposed, which provides a solution for widening the bandwidth of large-scale SIW slot arrays. The proposed antenna is composed of the backside waveguide feeding network and the upper SIW array. A novel method of loading biased metal vias on SIW is proposed to realize unequal power distribution. And it makes the antenna array to be compact, low-cost, and easy to manufacture. An antenna prototype is fabricated and measured. The measured bandwidth of the antenna array is 92.2–96.2 GHz within |S11|<−10 dB, and the measured maximum gain is 31.8 dBi at 94 GHz, which correspond to the radiation efficiency and aperture efficiency of 27.5% and 15.7%, respectively. The proposed antenna is an excellent candidate for millimetre-wave radar applications.

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.

Planar High-Gain Millimeter-Wave Slotted SIW Cavity Antenna Array with Low Sidelobe and Grating Lobe Levels

In this paper, a planar high-gain millimeter-wave (mmW) slotted substrate integrated waveguide (SIW) cavity antenna array with low sidelobe and grating lobe levels is proposed. The antenna consists of a slotted SIW resonator and an SIW transmission line (TL). To achieve a high gain and simplify the structure of the antenna element, the slotted SIW cavity is resonated in high-order mode. Then, a high-gain antenna array is implemented with only four such elements. By analyzing the pattern multiplication principle of the antenna array and accurately adjusting the element spacing, the high grating lobe level caused by the large spacing of the high-order mode resonator is considerably reduced. In addition, a one-four unequal amplitude power divider is introduced to further reduce the antenna array’s sidelobe levels (SLLs). Finally, the proposed antenna array is fabricated for verification. The measured peak gain is 21.4 dBi at 27.3 GHz. The measured grating lobe level in the E-plane is reduced to −17.9 dB, and the measured SLLs are lower than −19.1 dB.

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 high‐gain linear array of cross slots substrate integrated waveguide leaky‐wave antenna with defective ground structure

AbstractThis letter provides a detailed explanation of a novel high‐gain cross slot substrate integrated waveguide (SIW) rectangular cavity‐backed antenna. The main SIW cavity is further divided into seven small linearly placed cavities at a distance of 0.9. Each cavity contains a cross‐slot at an equal distance from each other. The defective ground structure is placed at the bottom layer of an antenna with two metallic vias to divert the wave towards edge slots for further gain improvement. The antenna shows a measured gain of approximately 12 dBi from 11.37 to 11.78 GHz. The radiation efficiency of 92% and the front‐to‐back ratio of 28 dB is achieved. The proposed antenna provides a very high directive fan‐like pattern which can be utilized for satellite and radar applications in the X‐band.

Design of Ka band substrate integrated waveguide slot traveling wave array antenna

Aiming at the requirements of Missile Radio Fuze Antenna with low sidelobe, narrow beam and specific directional pattern, a design method of Ka band substrate integrated waveguide (SIW) slot traveling wave array antenna is proposed. Based on the slot theory of SIW, the slot parameters and the excitation amplitude of Taylor linear array elements are calculated by MATLAB, and then the slot parameters and the excitation amplitude of array elements are optimized by Ansoft HFSS electromagnetic simulation software to realize the design of Ka band SIW slot traveling wave array antenna. The simulation results show that the Ka band SIW slot quasi traveling wave array antenna has a working frequency of 34.5 GHz, a gain of 14.2 dB, an E-plane beam width of 8° and a beam inclination of 20°, which can meet the requirements of missile radio fuze.

Endfire Circularly-Polarized Antipodal Linearly Tapered Slot Antenna Fed by Slotted Width-Tapered SIW

A low-profile single-layer endfire circularly-polarized (CP) antipodal linearly tapered slot antenna (ALTSA) is proposed and investigated through simulations and experiments. This antenna is a composite structure consisting of a novel width-tapered slotted substrate-integrated waveguide (SIW) and an ALTSA fed by the SIW. The former also serves as a radiator to produce vertically polarized radiation, which is crucial to achieve a fully planar endfire CP antenna when a thin substrate is deployed. Compared to the previous ALTSA fed by the SIW, this proposed antenna utilizes slots on the spare broad walls of the SIW to form an extra slotted width-tapered SIW radiator, which presents an extension of the conventional width-uniform slotted SIW. Moreover, there are no space harmonics in the slotted width-tapered SIW; it is a slow wave that produces the vertically polarized radiation. The proposed antenna is demonstrated at 28 GHz, which is one of the millimeter-wave bands specified for 5G. An experimental prototype of the antenna has an impedance bandwidth of about 9 GHz from 23.8 to 32.8 GHz and an axial ratio bandwidth of about 1.4 GHz from 27.35 to 28.75 GHz, which coincide well with simulated results.

Circularly Polarized Leaky-Wave Antenna With Natural Curl Property

This letter proposes a novel leaky-wave antenna (LWA) based on low profile substrate integrated waveguide (SIW), which can operate in either left-handed circular-polarization (LHCP) or right-handed circular-polarization (RHCP) mode. Different from other kinds of literature, the proposed SIW LWA is capable of CP state switching without introducing multiple LWA elements, phase-correct couplers or polarization converter, which is a single LWA element with a simple coaxial feeding/matching structure. Specially, the periodic slots on its radiation aperture are Archimedean spiral slots which are curved slots with curl property. These curled slots can excite vortex fields in the waveguide channel of SIW, and the generated vortex field is capable of changing vortex direction by selectively exciting the port of LWA, making the CP features flexible. The final Archimedean spiral slotted SIW LWA realizes LHCP or RHCP (AR < 3 dB) in the wide CP band of 27.7–34.6 GHz (BW = 22%), and the LHCP scanning range is from −51° to −10° while the RHCP beam scans from 10° to 50°.

Single-Pole Double-Throw Filtering Switch and its Application in Pattern Reconfigurable Antenna

In this communication, a low-cost, single-pole double-throw (SPDT) filtering radio frequency (RF) switch based on coupled resonators is proposed and utilized in a novel pattern reconfigurable antenna design. The proposed filtering switch employs two second-order quarter-wavelength microstrip resonant structures which can be controlled by p-i-n diodes, respectively. Compared with traditional switches based on p-i-n diode, this filtering switch can not only improve the RF response but also suppress the high-order harmonic, when it is used with an antenna. Then, a low-profile dual-port broadside/conical dual-mode antenna is proposed by embedding a slotted substrate integrated waveguide (SIW) cavity in the middle of a patch antenna. The slotted cavity is to realize the radiation in the broadside whereas the patch is fed by two probes in-phase to realize the conical radiation. Finally, the filtering switch and the dual-mode antenna are combined to realize the pattern reconfigurable antenna. By controlling the states of the p-i-n diodes, broadside and conical radiation patterns can be easily switched. The concept of switch-based pattern reconfigurable antenna is prototyped and experimentally verified. Measured results agree with the simulations, demonstrating a promising solution for pattern reconfigurable antenna designs.

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.