Slotted Rectangular Waveguide Research Articles

Self-Calibration Technique and Permittivity Measurement Using a Slotted Rectangular Waveguide

Self-Calibration Technique and Permittivity Measurement Using a Slotted Rectangular Waveguide

Design of Dual-Stopband Rectangular Waveguide Slot Array Antennas

A dual-stopband rectangular waveguide slot array antenna is presented in this paper. Firstly, a rectangular filtering waveguide with dual stopbands is realized by periodically loading a row of T-type resonators and a row of Π-type resonators on the bottom broad wall of the rectangular waveguide, and its dual-stopband characteristic is verified by analyzing the equivalent circuit and dispersion curve. Secondly, a dual-stopband rectangular waveguide slot array antenna is obtained by etching radiation slots on the top broad wall of the filtering waveguide. To verify the proposed concept, a dual-stopband rectangular waveguide four-slot array antenna is designed, fabricated, and measured. The measured results are in good agreement with the simulation ones. The results show that, compared with the conventional waveguide slot antenna, the proposed waveguide slot antenna has almost the same radiation performance in the –10 dB impedance bandwidth of 5.51–5.95 GHz, and achieves additional suppressions of greater than 24.5 dB in 6.6–7.1 GHz and 34.6 dB in 8.4–9.3 GHz, respectively, without occupying extra space.

A Novel Method to Broaden the Single-Mode Bandwidth of the Rectangular Waveguide

In this paper, a new class of broadband and low-loss transmission line called slotted rectangular waveguide (SRW) is proposed and analyzed. The proposed SRW consists of the rectangular waveguide and the inverted low-loss slotline, which can selectively suppress the higher-order mode (TE20 mode) and broaden the single dominant mode (TE10 mode) bandwidth in a rectangular waveguide (RW). The design principle and transmission characteristics of the SRW are illustrated and analyzed in this work. The transmission dominant mode bandwidth of the proposed SRW is analyzed and compared with the classic rectangular waveguide (RW), in which the dominant mode bandwidth of 60–155 GHz (88.4% bandwidth) is broader than the RW bandwidth of 60–116 GHz (63%). Two feed structures that can excite the two operating bandwidths (W and D band) of them separately are also designed. The SRW and transition exhibit broadband and low-loss characteristics from 75 GHz to 155 GHz, in which the transmission loss is lower than 0.68 dB and the return loss is over 18 dB.

Magnetically scannable slotted waveguide antenna based on the ferrite with gain enhancement

In this paper, a ferrite-filled rectangular waveguide as a balanced composite right/left-handed (CRLH) transmission line is considered. Based on the surface current density of dominant mode, a centerline longitudinal slot on the broad wall of this ferrite-filled rectangular waveguide can be radiate to the free space as a leaky-wave antenna (LWA). This proposed LWA has the both capability of the fixed-bias frequency scanning and fixed-frequency bias scanning from negative to positive angles. However, the gain of the centerline slotted ferrite-filled rectangular waveguide antenna is not acceptable. By adding another slot and changing the position of slots on the broad wall, the gain is improved to more than 9 dB in frequency range of 6.59–6.69 GHz.

Rectangular Grating Waveguide Slot Array Antenna for SATCOM Applications

This paper introduces a rectangular grating waveguide slot array antenna that provides a method for the design of satellite communication (SATCOM) receiving antennas. By integrating the radiating slots with a rectangular grating waveguide, which functions as a frequency-selective transmission line, the antenna realizes an extra filtering response. The operation bandwidth and out-of-band rejection of the antenna can be tuned by adjusting the rectangular grating waveguide parameters. In order to verify the proposed design concept, a prototype $Ku$ -band eight-slot rectangular grating waveguide slot array antenna is designed, fabricated, and measured, and its performance is compared with that of the conventional eight-slot rectangular waveguide slot array antenna. The results show that the proposed antenna works well in the receiving frequencies of 12.25–12.75 GHz and suppresses the realized gains with additional measured 14.8–21.3 dB in the transmitting frequencies of 14.0–14.5 GHz, which confirms its extra filtering response. Simultaneously, the measured antenna efficiency of the proposed antenna (68.3%–88.8%) is similar to that of the conventional antenna (66.9%–84.6%).

A Compact Highly Efficient Hybrid Antenna Array for W-Band Applications

A W -band hybrid array with a compact size and a high efficiency is presented. With the aid of the joint design of the series-shunt feeding network and substrate integrated waveguide (SIW) blocked slots array, the array with 16 × 56 slots can be divided into eight areas, and then the bandwidth of impedance, gain, and radiation pattern can be improved effectively. Moreover, it has both the advantages of low profile over traditional SIW planar array and low loss over traditional air-filled rectangular waveguide (ARW) slot array. Due to the utilization of back-feeding technology of the proposed hybrid array instead of planar SIW divider, it could save a lot of area for radiating energy and lowering the insertion loss, thus resulting in the gain values higher than 30.7 dBi during the entire operational frequency coverage. It is corresponding to the total efficiency of 26.5%, which is higher than the traditional W -band SIW array due to the usage of the back feeding to conserve the radiation acreage and reduce the insertion loss. By designing the SIW slots array and series-shunt feeding network simultaneously, low sidelobe level characteristics of −16 and −20 dB in E - and H -planes have been successfully accomplished, respectively.

Metasurface-Based Tapered Waveguide Slot Array Antennas for Wide Angular Scanning in a Narrow Frequency Band

We demonstrate the frequency scanning performances from a linearly tapered rectangular waveguide slot array antenna using the spatial angular filtering metasurface. To be more specific, the metasurface at the narrow side of the waveguide is shown to be capable of releasing different wavelength energies when under the illuminations from different incident angles, while the tapered waveguide is proposed to mimic the oblique incidence and thus functions as the excitation of the antenna. Such frequency scanning radiations can also be extended for both orthogonally polarized electromagnetic fields when integrated with another polarization selective surface properly behind the metasurface. Finally, we carry out the experiments to verify our proposed designs and demonstrate the excellent beam-scanning performances when the frequency is changing.

Radiation from a Millimeter-Wave Rectangular Waveguide Slot Array Antenna Enclosed by a Von Karman Radome

Radiation from a Millimeter-Wave Rectangular Waveguide Slot Array Antenna Enclosed by a Von Karman Radome

Slotted rectangular waveguide with dielectric sandwich structure inside

This paper continues the series of works devoted to the investigation of leaky-wave antenna based on layered rectangular waveguide with periodic transverse slots in broad face. Previously developed wavenumber calculation technique has been adapted for analysis of slotted sandwich waveguide with three layers at least. The paper provides the numerical results of velocity factor dependencies for partially filled slotted rectangular waveguide containing a dielectric slab in the middle position inside or an air gap between two dielectric slabs. Additionally, dispersion properties are also considered for multilayer waveguide with linear laws combinations of thickness and permittivity. This allows recognizing the trends to develop new prospective antennas with complex patterns of tilt angle change. All numerical results obtained are confirmed with the in-situ measurements of transmission coefficient phase.

A SRR loaded triple band slot array antenna with high gain, improved cross polarization, and front‐to‐back radiation

ABSTRACTThis article presents a split ring resonator (SRR) loaded triple band waveguide broad wall longitudinal slot array antenna. Three uniformly spaced SRRs have been placed on the transverse plane of a slotted rectangular waveguide. The measured result shows that the antenna has 10 dB return loss bandwidth of 8.38–8.62 GHz, 9.17–9.43 GHz, and 10.63–11.34 GHz. The gain and radiation pattern of the antenna are also plotted. The gain, cross polarization ratio, and front to back radiation ratio of the proposed antenna are found to be higher than that of a conventional broad wall longitudinal slot array antenna. An equivalent circuit of triple band antenna is also presented. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2500–2505, 2016

Microwave Characterization of Pb0.45Ca0.55(Fe0.5Nb0.5)1−x Sn x O3 Multiferroics at X-Band

The microwave characteristics of Pb0.45Ca0.55(Fe0.5Nb0.5)1−xSnxO3 multiferroics (x = 0.03, 0.06, 0.09, 0.12, 0.15) have been investigated as a function of frequency (8–12 GHz) and thickness for different substitutions of Sn4+ ions. The absorber testing device method is used to study microwave properties in the rectangular slotted waveguide. The condition of microwave signal after passing through different compositions has been reported. The quarter wavelength criterion is used to evaluate the microwave absorption. The large microwave absorption is observed at lower as well as higher substitution. Maximum reflected power has been found at higher substitution. The different compositions for electromagnetic applications have also been put forth.

Investigation of microwave absorption and DC electrical properties of Mn2+ and Ti4+ substituted SrMnxTixFe(12−2x)O19 ferrite

The microwave characterization of Mn2+ and Ti4+ ions substituted M-type SrMnxTixFe(12−2x)O19 hexagonal ferrite (x = 0.5, 1.0, 1.5 and 2.0) has been reported as a function of frequency, substitution and thickness in X-band. The static current density (J)-electric field (E) characteristics have been investigated as a function of substitution at an applied field from 4 kV/m to 40 kV/m. The microwave characteristics have been measured using microwave power meter in the rectangular slotted waveguide and the current density has been measured using electrometer. The microwave absorption has been evaluated using the standard model of quarter wavelength criterion. The microwave absorption is enhanced while electrical current density is decreased with the substitution of Mn2+ and Ti4+ ions. The different compositions have scope for microwave or high frequency absorber applications.

Wide-Beam SIW-Slot Antenna for Wide-Angle Scanning Phased Array

In order to enhance the scanning range of planar phased arrays, a planar substrate integrated waveguide slot (SIW-slot) antenna with wide beamwidth is proposed in this letter. The proposed antenna is fabricated on a single-layer substrate, which is fully covered with a metal ground on the back. The SIW works like a dielectric-filled rectangular waveguide working in the ${TE}_{10}$ mode. There are four inclined slots etched on the top metal layer following the rules of rectangular waveguide slot antenna. The electric fields in the slots work as equivalent magnetic currents. As opposed to normal microstrip antennas, the equivalent magnetic currents from the slots over a larger metal ground can radiate with a wide beamwidth. Its operating bandwidth is from 5.4 to 6.45 GHz with a relative bandwidth of 17.7%. Meanwhile, the 3-dB beamwidth in the ${x}{z}$ -plane is between 130° and 148° in the whole operating band. Furthermore, the SIW-slot element is employed in a ${1} \times {8}$ planar phased array. The measured results show that the main lobe of phased array can obtain a wide-angle scanning from $- {\hbox{71}}^\circ $ to 73° in the whole operating band.

Research on the propagation constant of the periodically slotted rectangular waveguide by equivalent circuit method

ABSTRACTThe influence of the structural parameters on the propagation constant of the leaky rectangular waveguide is studied by an equivalent circuit method and the dispersion equations are derived by the theory of transmission line. Using these equations, variation of propagation constant with the structural parameters is obtained and analyzed. And the propagation constants obtained from the equivalent circuit method were compared with those from the full‐wave simulation results. Both the results show that there is a critical length of the slots, below which the propagation constant of the leaky waveguide will be larger than that of the closed waveguide. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:426–429, 2016

LTCC Oversized Rectangular Waveguide Slot Array Antenna With Air Layers

A partially dielectric-filled structure of low-temperature cofired ceramics (LTCC) oversized rectangular waveguide slot array antenna with air layers both in the radiating and the feeding parts is presented. It has a new structure of partially filled coupling junctions in the feeding waveguide. The efficiency evaluation shows that the air-layer addition reduces the transmission loss both in the radiating and the feeding parts. The gain and bandwidth have been enhanced. The effective dielectric constant is reduced and it broaden the bandwidth of the series-fed feed junctions and the slot array. Using the LTCC with $\varepsilon_r = 6.6$ and $\tan \delta = 0.013$ , the dielectric losses of the feeding waveguide are reduced from 4.5 to 0.5 dB. The losses of the radiating waveguide are reduced from 3.7 to 0.45 dB. Experimentally, the gain was shown to increase 5.5 dB. The 3-dB-down bandwidth was improved from 1.4 to 2.1 GHz.

AC and DC properties of M-type SrCoxTixFe(12−2x)O19 hexagonal ferrite

Microwave characterization of SrCoxTixFe(12−2x)O19 (x = 0.0, 0.2, 0.3, 0.5, 0.6, 0.7, 1.0) ferrites has been studied as a function of frequency, substitution and thickness, and static electrical current density-electric field characteristics have been investigated as a function of substitution. Microwave characteristics have been measured using power meter in the rectangular slotted waveguide and current density is measured using electrometer. The microwave absorption is evaluated using the standard available model. The results depict −11.57 dB reflection loss at 10.38 GHz in composition x = 0.6. The electrical current density decreases at lower substitution and increases at higher substitution. The substitution of Co2+ and Ti4+ ions causes enhancement of electromagnetic and static electrical properties.

Ring-shaped omnidirectional rectangular slotted waveguide antenna with enhanced characteristics

Antennas are becoming crucial in an increasingly growing number of applications namely with the emerging of the wireless internet communications where efficiency, compactness and cost play a decisive role. Nonetheless a major drawback of such solutions is that the aforementioned criteria are hard to simultaneously optimize. In this paper an innovative approach relying on using circularly bent rectangular slotted waveguide antenna as an ultimate alternative is presented that allows drastically enhancing the ratio of performance versus cost and size. Simulation results were carried out at 2.4 GHz frequency and indubitably demonstrated high effectiveness in terms of directivity and high gain given a reduced cost, shape and size.

Numerical analysis of centered-inclined coupling slots in rectangular waveguides

Numerical analysis is presented for the characteristic parameters of centered-inclined coupling slot in rectangular waveguides, taking into account the transverse distribution of the electric field across the slot aperture. Integral equations are formulated based on dyadic Green’s function theories and solved using the method of moments. Trigonometric basis functions are adopted. It is found that the method will converge with up to ten basis functions. The characteristic parameters can be easily obtained for different slot sizes. Resonant length and resonant resistance of the coupling slots are calculated. It is shown that the calculated results have very high accuracy, compared with simulated results obtained from commercial software. Therefore, it can be effectively applied in the synthesis of antenna arrays. Effects of the transverse distribution on calculating resonant parameters of the coupling slot are also analyzed. The results show that if the transverse distribution of the electric field is neglected, the calculated error tends to become larger when the slot gets wider or thinner.

LTCC Oversized Rectangular Waveguide Slot Array Antenna With Air-Layer in the Radiating Part in the Millimeter-Wave Band

This paper presents an LTCC oversized rectangular waveguide slot array antenna with an air layer in the radiating part. The antenna is fed by an LTCC fully-filled waveguide. The air-layer addition reduces the transmission loss to enhance the gain. It also reduces the effective dielectric constant to enhance the bandwidth of the series-fed slot array. The measured near-field distribution shows the hard-surface sidewalls to enhance the field uniformity on the aperture by ensuring quasi-TEM mode propagation. The transmission loss in the radiating part with the addition of the air layer of half the height was reduced compared with conventional fully-filled LTCC antenna.

Simulation and experiment of radiating slot in a ground‐plane of microstrip junction

AbstractIn this article, a novel configuration of the integrated slot antenna is presented.This structure is based on the principle of radiation of the longitudinal slot in rectangular waveguide acquired by the slotted substrate integrated waveguides and half‐mode substrate integrated waveguide. The antenna arrangement is designed by etching longitudinal slot in the ground plane of the microstrip circuit. Such circuit is designed on a single substrate in the form of a microstrip line open at the end, with a stub attached to its edge. The length of the open stub is selected to produce a short circuit near the edge of the microstrip. The field distribution appearing then in the junction is well suited for slot excitation. The proposed integrated antenna configuration is validated by full‐wave simulation and experimental measurements. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 54:525–529, 2012; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.26576