Parallel-plate Waveguide Research Articles

The Effect of the Wall Thickness of the Material Loaded Cavity On the RCS Reduction

In this paper, the effect of a parallel plate waveguide's wall thickness on radar cross-section reduction (RCS) is rigorously analyzed for H-polarization by using the Wiener-Hopf Technique, when the waveguide region is loaded with dielectric material and terminated with a perfect electric conductor (PEC) plate. Transfer matrices are incorporated into the analysis to account for the effect of different material layers through continuity relations. The Fourier transforms of the diffracted field and the boundary conditions yield a modified scalar Wiener-Hopf equation of the second kind (MWHE-2). The classical procedure to solve the MWHE-2 is applied and the approximate expression of the diffracted far field is obtained. Numerical results are given by comparing with the results available in the literature for the case of the wall thickness of the cavity not being considered.

Statistical evaluation of electric field distributions in 3D composites with a random spatial distribution of dielectric inclusions

Electromagnetic applications of composites often impose constraints on the internal electric fields, such as an upper limit on the field strength to prevent local heating or dielectric breakthrough. However, owing to heterogeneity, the local fields in a composite differ from those in a homogeneous material. Moreover, they are accessible neither by experiment nor by effective medium theories, at least for arbitrary microstructures. In this work, we use numerical simulations to evaluate the electric field distribution and the effective permittivity for 3D systems of monodisperse impenetrable spheres dispersed in a continuous matrix phase. We restrict ourselves to loss-free dielectric materials and to a random spatial distribution of particles. Samples are placed in a parallel plate waveguide and exposed to a transverse electromagnetic wave. The local field amplitudes are calculated via the finite element method and are normalized to those of a homogeneous sample exhibiting the same effective permittivity and geometry. We analyze the distribution of the local electric field strength in both constituents, namely, particles and matrix. Thus, we evaluate mean values and standard deviations as well as the field strengths characterizing the highest and lowest percentiles. Increasing particle concentration or permittivity enhances heterogeneity, and so the local electric field strength in some domains can become much higher than its average value. The methods we apply here can also be used in further investigations of more complex systems, including lossy materials and agglomerating particles.

Propagation properties of plasma-filled parallel plate waveguide (PPWG) surrounded by black phosphorus (BP) layers

Propagation properties of plasma-filled PPWG surrounded by BP layers are explored in this research. Field equations are derived with the help of Maxwell’s equations. Boundary conditions x = d / 2 and x = − d / 2 are applied to obtain the characteristic equation for transverse magnetic (TM) mode. The influence of plasma frequency, electron doping, number of BP layers and core width on effective mode index are analyzed for armchair and zigzag conductivity of BP in the THz frequency range. It is concluded that armchair conductivity has a higher effective mode index compared to the zigzag conductivity of BP for the proposed waveguide structure. The presented results may have potential applications to fabricate black phosphorus-based nanophotonic devices in the THz frequency range.

Unveiling New IoT Antenna Developments: Planar Multibeam Metasurface Half-Maxwell Fish-Eye Lens with Wavelength Etching

This study introduces a groundbreaking antenna system, the directive Metasurface Half-Maxwell Fish-Eye (MHMF) lens antenna, tailored specifically for Internet-of-Things (IoT) networks. Designed to operate at 60 GHz, this antenna ingeniously integrates a dipole antenna within a parallel-plate waveguide to illuminate a Half-Maxwell Fish-Eye (HMFE) lens. The HMFE lens serves as a focal point, enabling a crucial high gain for IoT operations. The integration of metasurface structures facilitates the attainment of the gradient refractive index essential for the lens surface. By employing commercial Ansys HFSS software, extensive numerical simulations were conducted to meticulously refine the design, focusing particularly on optimizing the dimensions of unit cells, notably the modified H-shaped cells within the parallel waveguides housing the beam launchers. A functional prototype of the antenna was constructed using a standard PCB manufacturing process. Rigorous testing in an anechoic chamber confirmed the functionality of these manufactured devices, with the experimental results closely aligning with the simulated findings. Far-field measurements have further confirmed the effectiveness of the antenna, establishing it as a high-gain antenna solution suitable for IoT applications. Specifically, it operates effectively within the 60 GHz range of the electromagnetic spectrum, which is crucial for ensuring reliable communication in IoT devices. The directive HMFE lens antenna represents a significant advancement in enhancing IoT connectivity and capabilities. Leveraging innovative design concepts and metasurface technology, it heralds a new era of adaptable and efficient IoT systems.

A Genetically Based Algorithm to Improve Execution Speed in Multipactor Simulations in Parallel-Plate Waveguides

A Genetically Based Algorithm to Improve Execution Speed in Multipactor Simulations in Parallel-Plate Waveguides

Local oscillator port integrated resonator for Rydberg atom-based electric field measurement enhancement

Rydberg atom-based superheterodyne with additional local oscillator (LO) signal is a novel approach to detect electric field with high measured sensitivity. However, the LO signal is often supplied to the atomic vapor cell by free-space illumination, which lacks mobility and integration for practical applications. Here, we present a LO port integrated split-ring resonator for realizing high sensitivity-enhanced electric field measurements. The LO signal is sent directly to the resonator through a parallel-plate waveguide, which is shown to achieve a sensitivity enhancement of 32 dB. The integrated resonator has an electrical size of 0.088λ and the feed port S11 reaches −38.2 dB.

Terahertz on-chip sensor based on Mach-Zehnder waveguide interferometer for selective recognition of reducing drug

The selective detection of biochemical substances with high sensitivity in the terahertz (THz) band has emerged as a prominent research area, attracting significant attention. Waveguide-on-chip detection of biochemical substances can effectively enhance the interaction between samples and waves, but there is a lack of reports in the THz band. In this work, a dual-channel metallic parallel-plate waveguide (PPWG) is applied to creatively construct a THz Mach-Zehnder interferometer (MZI) sensor for highly sensitive and selective detection of reducing drug on a chip. This sensor exhibits a strong numerical response of 0.75 THz/RIU, allowing for dynamic sensitivity adjustment through mechanically tuning structural parameters, and it is modified through in-situ growth of Prussian blue (PB) to achieve the selective detection of reducing drug. The experiments confirm that the designed sensor-on-chip possesses exceptional detection sensitivity for cysteamine, reaching an impressive maximum sensitivity of 0.09 GHz/nmol and a low limit of detection of 88 nmol. The modified chip exhibits selective detection of cysteamine, demonstrating a maximum response difference of 4.2 times compared to other configurations. Collectively, a pioneer validates the feasibility of the highly sensitive MZI chip in the THz regime and opens up new possibilities for advancing THz biochemical sensing.

Electromagnetic near-field mutual coupling suppression with active Janus sources

Electric dipoles and magnetic dipoles are the most fundamental particles in electromagnetic theory. Huygens and Janus sources, formed by the orthogonal combination of electric and magnetic dipoles, both show good directionality in the near field. Although the Huygens source has been widely used in antennas and metasurfaces, the applications of Janus source are heretofore limited. In this paper we report the physical construction of an active Janus source. Through full-wave simulations within the parallel plate waveguide (PPW) environment, we show that our source achieves the directional electromagnetic near-field and quasi-isotropic far-field requisite of the Janus source. Using this fact, we demonstrate that two active Janus and Huygens sources in close proximity (about 0.10 to 0.25 wavelengths) achieve a near 1000-fold reduced mutual coupling compared to electric dipole sources. Particularly, the simultaneous achievement of strong mutual coupling suppression and quasi-isotropic radiation make the Janus source an ideal candidate for consideration in future compact multi-input multi-output (MIMO) communication systems.

Cold plasma-induced effects on electromagnetic wave scattering in waveguides: a mode-matching analysis

This article presents advancements in an analytical mode-matching technique for studying electromagnetic wave propagation in a parallel-plate metallic rectangular waveguide. This technique involves projecting the solution onto basis functions and solving linear algebraic systems to determine scattering amplitudes. The accuracy of this method is validated via numerical assessments, which involve the reconstruction of matching conditions and conservation laws. The study highlights the impact of geometric and material variations on reflection and transmission phenomena in the waveguide.

Design and fabrication of waveguide‐based graded refractive index Rotman lens with an improved insertion loss at Ka‐band

AbstractThe design and optimisation of a five‐cascade layer Rotman Lens based on waveguide with a graded refractive index at Ka‐band frequency are presented. The proposed lens incorporates 5 layers within the cavity, utilises a modified three focal Rotman lens design methodology to achieve perfect phasing for true time delay beam steering, and optimises each layer's parameters such as refractive index, vertex location, and contour angle to improve insertion loss between input ports and output array elements. This approach enhances energy concentration between input and output ports, reducing spillover to dummy ports. The graded layers are formed using periodic cubic metallic posts with varying heights within a parallel plate waveguide. The results show an average improvement in the insertion loss of 16% and a peak improvement of 48% across the bandwidth when compared to conventional Rotman lenses. The normalised average phase error across the array elements for all beam ports excitation is 4 × 10−3 and the peak degradation of the main beam during beam scanning from 0° to ±22° varies from 0.7 to 1 dB at different frequencies operating in the Ka‐band (24–30 GHz) with potential applications for 5G communications. The simulation results demonstrate good agreement with the measurement results.

Imaging of cylindrical inhomogeneites in a parallel plate waveguide with reverse time migration method

Abstract While reverse time migration (RTM) algorithm is commonly used in geophysical explorations, this paper addresses the RTM imaging procedure for reconstructing of lossy dielectric discontinuities in a planar waveguide using electromagnetic waves at a single frequency. The direct problem of the related configuration is solved via method of moments (MoM) to produce the synthetic scattered data to be used in RTM. The achievements of the method are examined and verified by including different numerical examples. It is shown that the RTM approach can be used as an alternative imaging methodology in parallel plate waveguide problems.

Coupled line waves in parallel-plate metasurface waveguides

Coupled line waves in parallel-plate metasurface waveguides

A Dual-Polarized CTS Array Antenna with Four Reconfigurable Beams for mm-Wave Wind Profile Radar

The wind profiler radar (WPR) system requires a dual-polarized antenna with multiple low-sidelobe and high-gain beams to facilitate the detection of weak signals reflected by atmospheric turbulence. This paper proposes a dual-polarized continuous transverse stub (CTS) K-band antenna with four reconfigurable beams, which comprises a series-fed CTS array and four 1-to-14 power dividers as line source generators (LSGs) to generate a high-quality quasi-TEM wave. The CTS element incorporates a stepped transition radiation stub design and employs a short cutoff stub on the upper surface of the series-fed parallel plate waveguide (PPW) to achieve optimal impedance matching. The entire antenna is an all-metal structure with remarkably low loss, and low-cost standard fabrication processes are employed for the prototype, which achieves fast reconfigurable four-beam scanning to 15°, with a gain of 31.09 dBi and sidelobe levels below −17.6 dB. Measurement results in an anechoic chamber agree well with simulations, demonstrating the antenna’s ease of manufacture, stability, and suitability for wind profile radar applications.

Design, Realization and Testing of an Adaptable Folded Parallel Plate Waveguide Feeding Network

Design, Realization and Testing of an Adaptable Folded Parallel Plate Waveguide Feeding Network

Polarization Control of Terahertz Waves Based on Metallic Parallel-Plate Waveguides

Polarization Control of Terahertz Waves Based on Metallic Parallel-Plate Waveguides

Electromagnetic jet produced with loaded waveguide ended by an optimized multi-rectangular sections tip

Previous works have demonstrated that a parallel plate waveguide, equipped at the end with a tip, can be used to initiate an “electromagnetic jet (Ej)” (this name generalizes the photonic jet (Pj) phenomenon regardless of the wavelength). In addition to being easy to manufacture, a rectangular shape improves energy concentration, however concurrently the full-width at half maximum (FWHM) is slightly degraded. This article aims to introduce tips with multi-rectangular sections reducing the drawbacks previously mentioned. This article proposes the use of Aperiodic Polynomial Modal Method (A-PMM) as an efficient yet robust method to model and optimize an outgoing Ej, equipped with this kind of dielectric tips. Thus, a three rectangular sections tip can improve energy concentration and can reduce the FWHM beyond the diffraction limit compared to a single section tip.

A slotted metagratings leaky-wave antenna with theoretical analysis

In this contribution, a new slotted metagratings based leaky-wave antenna (MGs LWA) featuring a wide beam-scanning is presented to overcome the limitation of the mutual coupling and the open-stopband effects in traditional LWA. The MGs LWA is comprised of a parallel-plate waveguide with a periodic MGs array etched on the top plate over a dielectric substrate with PEC-backed. An analytical theory is created as a conceptual model for the corresponding equivalent electromagnetic fields produced by slotted MGs, that generate the Z-matrix and S-matrix for a two-port structure from the electric and magnetic fields. Furthermore, an approximate analysis is derived using Green’s function to quantify mutual admittance coupling. This antenna has excellent success due to its ability to achieve a wide beam-scanning range with a high realized gain while still having a narrow beam width in the E-plane. With the utilizing results, the bandwidth range of 64% with continuous beam-scanned of 74° and narrow angular beamwidth up to 11.1° in the E-plane is obtained. Meanwhile, the beam-scanned sensitivity is 5.4°/GHz. The realized gain is up to 16.3 dBi. Finally, the MGs LWA is fabricated to approve the theoretical and simulation results. Thus, a low permittivity and thin substrate are selected to enable perfect beam-scanning for 5 G high-speed mobile communication systems.

A Study on Evaluation Method for Beam Profile of Phased Array by Using Two-Dimensional Measurement Equipment

Recently, “Both-Side Retrodirective System” was proposed, as a beam convergence technique, for microwave high power transmission. To demonstrate the effectiveness of the both-side retrodirective system by experiment, the authors propose a 2-dimensional measurement equipment. Propagation in the parallel plate waveguide was analogized based on free-space propagation, and the theory and characteristics were clarified by simulation. The electric field distribution in the waveguide was measured by electric probe with the proposed equipment. Two types of measurement equipment were developed. One is a 4-element experiment system, which is a small-scale device for principle verification. The other is a 16-element measurement equipment, which is intended to evaluate beam convergence of a both-side retrodirective system in the next step. The measured results were compared with simulation results. As a result, it was confirmed that the beam formed in the waveguide was successfully measured. Thus, the effectiveness of 2-dimensional measurement equipment for evaluation of beam convergence was shown.

Design of a wideband vertically polarized omnidirectional antenna for covering 960–1250 MHz frequency band

This paper deals with the design and fabrication of a wideband vertically polarized omnidirectional antenna. The antenna unit of the array comprises four radiating dipoles fed by a parallel plate waveguide. A prototype is designed and measured in order to experimental verification. The acceptable agreement between the measurement and stimulation results validates the performance of presented antenna. The experimental results demonstrate that the VSWR < 2 impedance bandwidth of presented antenna can reach 97% from 0.64 to 1.84 GHz. Also, the maximum realized gain is about 5.2 dBi in the operating frequency range. The findings show that the antenna demonstrated has the capabilities to be used in wideband communication systems.

A Planar Shared-Aperture Co-Polarized Array Antenna With a High Isolation for Millimeter-Wave Full Duplex Communication

We provide the design of a co-polarized simultaneous transmit and receive (STAR) array antenna, aiming to address the issue of undesired isolation in the antenna domain of the millimeter-wave (mm-Wave) full-duplex co-polarized communication system. As the cornerstone for the design and development of the antenna, the guided-wave structures of the virtual-electric-wall (VEW)-based ridge substrate-integrated waveguide (RSIW) and ridge parallel plate waveguide (RPPW) are proposed and applied to the full-duplex antenna design. Compared with conventional RSIW, VEW-based RSIW has the merits of lower ohmic loss and releasing the fabrication tolerance in the array antenna. Additionally, on the basis of parallel plate waveguide (PPW), the proposed RPPW exhibits a Chebyshev filtering response. The radiating part of the proposed array employs a slot-pair array excited along orthogonal directions by using the preceding guided-wave structures. Among them, the RSIW array serves as the Tx antenna, and the RPPW array is regarded as the Rx antenna. To achieve co-polarized radiation patterns in the boresight direction, the substrate-integrated waveguide (SIW) feed network is integrated into the reverse side of the antenna, providing differential and common-mode excitations for the RSIW-excited and RPPW-fed arrays. Furthermore, the inter-port isolation is effectively ameliorated by inserting the mushroom-type metamaterial between linear arrays. As a proof-of-concept, a shared-aperture full-duplex array operating in the Q-band is developed and fabricated to demonstrate the above concept by using standard printed circuited board technology. The measured overlapped impedance bandwidth covers from 38.18 GHz to 39.13 GHz. The measured Tx-to-Rx isolation is greater than 25.5dB in the Q-band. The measured peak gains in Tx- and Rx-mode are 18.4 dBi and 17.8 dBi. The simulation and measurement results show good consistency, verifying the effectiveness of the proposed array in inter-port isolation, array size, planarization, and lightweight, making it suitable for mm-Wave shared-aperture full-duplex communication systems.