TM Modes Research Articles

Ultra‐wideband directional electrically small antenna for UHF through C‐band 5G and beyond 5G applications

AbstractA semi‐spherical combined transverse electromagnetic (TEM) horn and loop antenna is designed for directional ultra‐wideband operation from 0.42 to 6 GHz for 5G and beyond 5G applications across military and commercial sectors. The antenna structure fits within a sphere with 3‐cm radius, thus operating as electrically small over the lower part of the band (ka = 0.5 at 0.795 GHz and ka = 1 at 1.59 GHz). To spread the currents across the volume while maintaining the required relationship between the lowest order TE and TM modes, the loop section is modified to conform with the enclosing minimum sphere. The TEM horn, bowtie, and resistive loading are then tuned to achieve improvement over the conventional topology in the radiation efficiency by >7% when ka = 0.5 and >22% when ka = 1.

Analysis and characterization of structural, dielectric and magnetic properties of MgxCo(0.90−x)Zn0.10Fe2O4 nanoparticles based flexible metamaterial absorber for wireless communication

The anisotropic flexible metamaterial absorber (FMA) structure comprises a resonating layer, a ferrite-based flexible substrate layer, and a back layer. The sol-gel method is used to prepare the ferrite-based nanomaterial for enhancing absorbability. The solution prepared material is according to the formula of MgxCo(0.90−x)Zn0.10Fe2O4 and specified as X25, X50, X75 for X = 25%, 50%, and 75%, respectively. Then the proposed ferrites materials are characterized by XRD, and FESEM, respectively. Moreover, the magnetic and dielectric properties of the proposed MgxCo(0.90−x)Zn0.10Fe2O4 ferrites samples were explored for microwave applications. The dielectric constants and loss tangents of the fabricated, flexible substrates are measured at a frequency range of 3–7 GHz using the DAK 3.5. The computed relative permittivity values are 2.95 for X25, 3.55 for X50, and 4.05 for X75, respectively, while the loss tangents values are 0.00295 for X25, 0.00495 for X50, and 0.00695 for X75. Whereas the permeability and magnetic loss tangent values varied from 0.875 to 1.00 and 0.00225–0.00585, respectively. Finally, the resonators of the absorber consist of a Y-style shape, square-shaped metallic plate resonator, square ring resonator (SRR), and cross-liked shape. The proposed flexible metamaterial absorber (FMA) structure is developed on MgxCo(0.90−x)Zn0.10Fe2O4 nanomaterial-based flexible substrate with dimensions of 0.110λ x 0.110λ x 0.017λ to validate the design experimentally. The electrical dimension is calculated at a 5.5 GHz resonance frequency. The simulated results from the CST Microwave Studio simulator reveal that absorption peaks at 5.5 GHz with a 99.99% absorption that includes the C band frequency that can be used in satellite applications. The proposed FMA structure achieved a 60° incident angle response for TE and TM modes. The structure has superiority with compact dimensions, lightweight, and flexibility and can be used for C band wireless communications.

Numerical evaluation of an external environment effectiveness to the surface plasmon mode in Au slot waveguide for design the sensor simulation

The effective permittivity of gold thin films with an external thin dielectric layer on the top and core of the slot waveguide was evaluated as an effective compound semi-metal layer of the surface plasmonic polariton slot waveguide that will vary due to some environmental factors. By uses simple parallel and series permittivity of compound material, this value need for the computation of the effective propagating vector βsp. This takes for a sensor model designing which the external environment effectiveness was changed by the surface plasmonic mode in its slot waveguide. So the resonance length and grating period are evaluated for the sensor model in the first. Further, the propagation of the SPP surface wave mode along the interface between the compound cladding and Si dielectric waveguide is computed, while the effective refractive index of the compound cladding of the slot waveguide is increased from 1 − 1.50. The computation results showed that the TM0 mode power transfer and propagation length seem to vary with this effective refractive index of the compound cladding on the surface plasmonic polariton waveguide. The 140 nm gap width and 3.70 mm long waveguide is also simulated by the finite different time domain method in the optiwave program, where the TM0 mode transition output is corrected, while the refractive index of the environment layer is changed. The results of the simulation showed good agreement with the computation in that the TM0 mode depends on the external refractive of index and input wavelength. This result shows that loss peak ships vary with the external refractive index thin film layer and input wavelength. Thus, they seem to be useful for sensor applications such as the solution concentration analytic.

A Single-Layer Wideband Differential-Fed Filtering Antenna With High Selectivity

In this communication, a single-layer, wideband, differential-fed filtering antenna with high selectivity is proposed. The developed filtering antenna possesses a simple structure and consists of a square patch, a square substrate integrated waveguide (SIW) cavity, a pair of symbiotic stepped impedance resonators (SSIRs), and a pair of complementary split ring resonators (CSRRs). The SIW cavity formed with sparse metallized posts is embedded in the square patch, and the impedance bandwidth can be broadened by merging the TM10 mode of the square patch, excited by the electromagnetic energy escaping from the sparse posts, with the TE210 mode in the SIW cavity through differential excitation. The SSIRs are connected with both radiating edges of the square patch. And two extra in-band resonances together with an upper-edge radiation null are simultaneously generated, so the impedance bandwidth and the frequency selectivity at higher stopband can be significantly improved. The CSRRs, surrounding around the differential excitation ports, are etched into the bottom surface of the SIW cavity, and a lower-edge radiation null is produced to further sharpen the roll-off rate. By adjusting the geometrical parameters of the SSIRs and CSRRs, the positions of the two radiation nulls can be independently controlled. For verifying the design method, a prototype of the developed single-layer filtering antenna has been fabricated and tested. The measurement results are well consistent with the simulated values, indicating good performance with a large -10 dB fractional impedance bandwidth of 21.2%, a peak realized gain of 9.3 dBi, two out-of-band rejection levels more than 26 dB, and very high selectivity.

A Noncontact Planar Microstrip Sensor for Power Line Fault Detection

In this letter, a novel TM0 mode launcher is presented as a sensor for the fault detection on a single conductor line (SCL). The launcher is designed at 2.4 GHz frequency on an FR4 substrate with the microstrip technology. Simulated S-parameter results of the launcher are verified with the measured results of the fabricated prototype. Experiments are performed to demonstrate the signal propagation on a bent SCL, to measure the isolation between the launchers and to measure backward propagating signal. Open circuit fault location experiment is performed on a 6 m long cable using the Time domain reflectometry (TDR) technique. An average error of 0.15 m (5.04%) is observed in fault location. The proposed sensor is non-conductor-contact, non-intrusive, planar (16 cm*16 cm) and easy to install on the existing power lines for fault detection and power line communication.

Design and Analysis of Si/CaF<sub>2</sub> Near-Infrared (λ∼1.7µm) DFB Quantum Cascade Laser for Silicon Photonics

We have designed a near-infrared wavelength Si/CaF2 DFB quantum cascade laser and investigated the possibility of single-mode laser oscillation by analysis of the propagation mode, gain, scattering time of Si quantum well, and threshold current density. As the waveguide and resonator, a slab-type waveguide structure with a Si/CaF2 active layer sandwiched by SiO2 on a Si (111) substrate and a grating structure in an n-Si conducting layer were assumed. From the results of optical propagation mode analysis, by assuming a λ/4-shifted bragg waveguide structure, it was found that the single vertical and horizontal TM mode propagation is possible at the designed wavelength of 1.70 μm. In addition, a design of the active layer is proposed and its current injection capability is roughly estimated to be 25.1 kA/cm2, which is larger than required threshold current density of 1.4 kA/cm2 calculated by combining analysis results of the scattering time, population inversion, gain of quantum cascade lasers, and coupling theory of a Bragg waveguide. The results strongly indicate the possibility of single-mode laser oscillation.

Manipulating leaky mode in silicon waveguides harnessing bound states in the continuum.

A low-loss ridge waveguide is proposed and demonstrated with a novel, to the best of our knowledge, bound state in the continuum (BIC)-based structure on the silicon-on-insulator (SOI) platform. The presented waveguide is designed appropriately to suppress TM-mode leakage, and has a theoretically low propagation loss of ∼0.0027 dB/cm at 1550 nm. In the wavelength range from 1530 nm to 1600 nm, the 2-mm-long waveguide can achieve an average loss suppression of ∼30 dB in the experiment. Such a novel ridge waveguide structure can also be introduced into narrowband optical filters. The fabricated Bragg grating filter working at the TM mode can achieve a narrow bandwidth of ∼1 nm and an extinction ratio of ∼14.8 dB.

Modelling a near perfect temperature tunable multiband VO2 based photonic-plasmonic absorber within visible and near infrared spectra

This work demonstrates thermal and optical stability with multiple near perfect absorption in a polarizing sensitive one-dimensional vanadium dioxide (VO2) graphene-based nanocomposite plasmonic structure within visible to infrared region (IR). Proposed structure in each phase of VO2 has multiple perfect optical absorption peaks within visible range with a Q-factor near ∼45 which leads the structure to work like an optical switch. An increase in absorption is achieved through plasmonic polaritons of a nearby Ag thin layer directly or through photonic crystal. The temperature turnability of VO2 leads the proposed structure a tunable optical absorber with a hysteresis loop from low to nearly perfect absorbance spectrum. The octonacci quasi periodic proposed structure has highest multiple perfect absorber spectrum comparing other photonic sequences. The peaks of absorption have blue shifted with an increase in volume fraction in both phases. The optical absorption of the structure in metal phase mode alters from wide band to multiple narrow bands with the increment of permittivity of the host composite material within the 1000–1600 nm range. The absorption maximizes in TE mode comparing TM mode due to polarization sensitivity. The structure with optimal thickness and volume mixing ratio in composite has temperature dependency with a thin layer of VO2 has ∼90% absorption. The absorption of the structure can be tuned in both heat and cool mode function of the phase change material (PCM) at an optimum frequency within visible to IR spectrum. These thermal bistable activities may enhance the optical features of the devices.

Evaluation of the applicability of microwave nondestructive testing to crack detection on a pipe inner surface

This study explores the applicability of microwave nondestructive testing to detect a metal pipe’s inner crack. Three-dimensional finite element simulations were conducted to study the inspectability of cracks using microwaves in different modes and the dependency of the reflection characteristics of microwaves on crack size. The simulation results showed that microwaves in the TM01 and TE01 modes can detect circumferential and axial cracks, respectively. The positive relationship between crack size and intensity corresponding to the reflected microwaves was obtained in simulations and then verified by experiments. In both simulations and experiments, the axial crack length showed a small influence on the results, especially for shallow crack detection. In the experiments, circumferential and axial cracks with a width of 0.3 mm were detected using microwaves. The experimental results revealed that signal amplitudes decreased when a slit penetrated a pipe wall, probably due to a microwave leakage.

Monolithically integrated polarization rotator and splitter with designed power ratio.

Inverse designs are widely used for creating ultra-compact photonic devices, but suffer from high computation power due to the optimization complexity. General Stoke's theorem proves that the overall change present at the outer boundary is equal to the integral of the change over the inner intervals, providing the possibility to divide one sophisticated device into several simple building blocks. Thus, we integrate this theorem with the inverse designs as a novel design methodology for optical devices. Compared with conventional inverse designs, the separated regional-optimisations can reduce the computational complexity significantly. The overall computational time is around five times shorter than optimizing the whole device region. To validate the proposed methodology, a monolithically integrated polarization rotator and splitter is designed and fabricated to demonstrate the performance experimentally. The device achieves polarization rotation (TE00 to TE00 and TM00 modes) and power splitting with the designed power ratio. The exhibited average insertion loss is <1 dB and the crosstalk is <-9.5 dB. These findings confirm the advantages of the new design methodology, as well as its feasibility for achieving multiple functions on one monolithic device.

Wideband Dual-Polarized Differential-Fed Filtering Microstrip Patch Antenna with High Suppression and Wide Stopband

This paper presents a wideband dual-polarized filtering antenna with high suppression level and wide stopband. In the proposed antenna, the driven patch operates in a TM10 mode with an inherent radiation null caused by a higher mode TM12. Four dual-strip structures connected with the feeding probes are placed below the driven patch to achieve the capacitive coupling, thus resulting in a low-frequency radiation null with a sharp roll-off rate. The introduction of the parasitic patch and strips generates an in-band resonance and two high-frequency radiation nulls, which widens the upper stopband. Four slots are etched on the driven patch to excite the third resonance, thus achieving the wide operation band. The prototype of the proposed antenna is fabricated. With four controllable radiation nulls, the out-of-band suppression levels are above 29 dB in low-frequency band greater than 1 GHz and above 21 dB in high-frequency band up to 7 GHz, respectively. Due to the three in-band resonances, a wide impedance bandwidth of 2.93-3.96 GHz with a fractional band of 30% is obtained. With the rotational symmetry structure driven by differential probes, the proposed dual-polarized antenna has a cross-polarization ratio better than 28 dB, a high polarization isolation above 43 dB, and a good peak gain about 9.9 dBi.

Wideband microstrip antenna operating in TM01 mode and its array with compact feed network

AbstractThis letter presents a broadband linearly polarized (LP) microstrip antenna operating in TM01 mode and its 2 × 2 array with a compact network. Different from the TM10 mode, the TM01 mode can be used to design arrays without a bending feed network. The impedance bandwidth (IBW) of the proposed antenna is 9.6% (2.19 GHz–2.41 GHz). Subsequently, the characteristic of this antenna operating in TM01 mode is employed to design a 2 × 2 planar array. The measured results show that the array has an IBW of 9.5%, a maximum gain of 11.4 dBi with low cross‐polarization.

Efficient Fiber‐to‐Chip Interface via an Intermediated CdS Nanowire

AbstractAn efficient fiber‐to‐chip interface via an intermediated CdS nanowire is demonstrated. The fiber mode is firstly squeezed through a fiber taper drawn at the end of a single‐mode fiber, then evanescently coupled into an intermediated CdS nanowire with a longitudinally tapering profile, and finally coupled into an on‐chip silicon waveguide (SiW) via a waveguide taper fabricated on it. Since the fiber‐nanowire‐SiW cascade structure is designed to match effective indices in each coupling area, such a fiber‐to‐chip interface ensures a bidirectional coupling efficiency up to 90% and a 3‐dB bandwidth over 100 nm in experiments. The difference of coupling efficiencies between the TM or TE modes is less than 0.5 dB in the spectral range of 1545–1635 nm. The footprint of the on‐chip coupling structure is about 10 µm in size. The results may provide a compact, efficient, and versatile fiber‐to‐chip interface in applications including optical interconnects, coherent communication, and quantum optical circuitry.

Investigation of a Very Sensitive Refractive Index Sensor Based on Waveguide TM Mode Resonance and Design of a Plasmatic Sensor

This study proposes a highly sensitive refractive index sensor based on the TM wavelength resonance excited in a structure of a plasmonic sensor. The results show that the resonance wavelength will shift significantly with increasing and changing the refractive index, which shows that this method can be used to understand the resonance wavelength and refractive index. Based on this approach, the sensing characteristics, including the sensitivity and the figure of merit (FOM) and the Q quality factor, have been investigated, where the sensor sensitivity has reached 1165 nm / RIU. Compared to plasmon surface resonance sensors, which are based on a similar structure, the proposed sensor can achieve a more flexible range of wavelengths and a wider range of refractive index. Therefore, this method has tremendous potential for use in various fields of measurement, such as biochemical analysis and medicine, and can find useful applications in measurement systems and integrated circuits. Also, all the diagrams obtained in this research have been drawn using MATLAB program.

Compact size Zr–Fe2O3 inspired metal-dielectric angle and polarization insensitive nanostructure for efficient solar energy absorption

We exhibit the perfect solar design by using Ferric Oxide (Fe2O3) as the substrate layer, and the Zirconium (Zr) material based resonator. The overall solar absorption is 95.79% and the solar absorption are obtained for the ultraviolet (UV), visible (V), near-infrared (NIR), and mid-infrared (MIR) regions respectively between the wavelength ranges 0.2 μm and 3 μm. Subsequently, the absorption is above 95% for the 2800 nm bandwidth, and in the 1040 nm bandwidth, the absorption is above 97%, and above 99% for the bandwidth of 500 nm. Moreover, the variation of the solar absorption rates by changing the parameters of resonator thickness, substrate layer thickness, and resonator width of the developed design is explored in detail to attain the optimal structure. And then, the analysis of the absorption rates in TE and TM modes with the incidence angle degrees from 0 to 80 verified the absorber's performance attributes. In the end, the electric field intensity situation of the proposed design is demonstrated to validate the performance of the proposed absorber. The proposed solar absorber can be employed as it can convert solar radiation into heat completely and can be used for various solar thermal applications such as solar thermal photovoltaics, solar generators, and solar power plants.

Dual-layer microstrip monopolar patch antenna with characteristic mode analysis

Abstract A monopole-like stacked microstrip antenna with dual-layer patches is proposed for ultra-wideband applications. The characteristic mode analysis (CMA) is utilized and contributes to the multi-mode behavior investigation, guiding the design process. The dual-layer patches both consist of two concentric-coupled rings. The patch configuration is optimized according to the desired mode behaviors at different frequencies. Correspondingly, the three merged resonant modes, containing the modes TM01 and TM02 of the middle layer and TM01 in the top layer, effectively broaden the operation band. The measurements demonstrate that the impedance bandwidth (IBW) of the antenna reaches 4.70–10.20 GHz (73.8%) with the return loss of 10 dB and a maximum gain of 8.7 dBi. The cross-polarization level is better than −28 dB. The proposed antenna possesses a small radius of 30 mm (0.47 λ L ${\lambda }_{L}$ ), and a low-profile of 5.78 mm (0.09 λ L ${\lambda }_{L}$ ). λ L ${\lambda }_{L}$ is the free-space wavelength at the lowest operation frequency.

Open-Circuit Fault Detection in a Single Conductor Transmission Line Using TM0 Mode Launcher

A novel surface wave (SW) launcher design for power line fault detection is presented in this paper. The launcher is capable of converting TE10 to TM0 mode and exciting SW signal at 5.5 GHz frequency with high efficiency, on a single conductor line. The average attenuation of 2 dB/m and front to back ratio of 19 dB are observed and verified by simulation and experiments. Effect of bend, nearby obstacles, and extra wire connection on SW propagation is also investigated by experiments, and corresponding S-parameter results are presented. The optimization of launcher design with dielectric window and conical back plate is also demonstrated. The proposed launcher is compact and lightweight and can be easily installed without damaging the conductor line. Close structure makes it capable of withstanding outdoor environmental conditions. Using this launcher, microwave signal can be efficiently transmitted and received over existing conductor lines such as live power lines, pipes, and HVAC ducts, and it can be used in applications such as power line communication, fault detection, and permittivity measurement.

A novel microstrip fed triple band patch antenna with TM10, TM02 and TM12 induced modes

In this study, a patch antenna with three different operating frequencies (2.94 GHz, 4.5 GHz, and 5.7 GHz) is proposed. The dimensions of the antenna are as follows: 23.4 mm by 30.4 mm by 1.6 mm. The triple band characteristic may be achieved by adjusting the width of the quarter wave transformer (QWT), which in turn modifies the impedance matching in such a manner as to excite the TM10, TM02, and TM12 modes. These modes are able to have additional verification provided by the current distribution on the patch. Altering the width of the QWT provides the proposed antenna with the ability to fine-tune its resonant frequencies. At the resonant frequencies, the impedance bandwidths of -10 dB are 69 MHz, 40 MHz, and 110 MHz, respectively. 5.7 GHz has a gain of 1.5 dB, while 4.5 GHz has a gain of 0.7 dB, and 2.94 GHz has a gain of 2 dB. Additionally, this antenna finds its applications in wireless systems in the S and C bands of the frequency spectrum. The antennas are validated using a vector network analyzer (VNA) after being simulated with mentor graphics software three-dimensional electromagnetic modeling (3DEM) and analyzed with it.

Balanced-to-Unbalanced Filtering In-Phase Power Divider Based on 2-D Patch Resonator

In this letter, a new balanced-to-unbalanced (BTU) in-phase power divider with bandpass filtering response is proposed based on 2-D patch resonators. With resorting to the electric field distribution of the fundamental TM01 mode in a square patch cavity, the desired out-of-phase input signal and in-phase output signal can be generated and applied for BTU power divider design. In order to attain good bandpass filtering response, two coupled patch resonators with a proper coupling strength in a stacked form are adopted. As such, high isolation between two output ports can be well achieved with the help of two grounded isolation resistors. For verification, a prototype of BTU filtering in-phase power divider working at 4.0 GHz with a fractional bandwidth (FBW) of 13.7% is implemented. Measured results are in good agreement with the simulated ones, confirming the design concept experimentally.

High-Efficiency Diagnosis of Antenna Radiation Characteristics Based on Scanning Optic-Induced Plasma Scattering Technology

This article presents an innovative quasi-real-time antenna near-field diagnosis method, by scanning a laser-induced plasma on a silicon wafer and imaging the field with the synchronously produced scattered signals. Several approaches have been devised to adapt to the antenna diagnosis scenarios. By using the multilayer matching approach, the issue of multiple reflection disturbance between the aperture and silicon wafer is avoided, especially for large aperture antennae at high frequencies. The accuracy of near-field distribution is improved, and far-field patterns can be transformed directly. The experimental results of a Ka-band 20 dB standard antenna agree well with the simulation results. Diagnosis of radiation states in the reactive near-field region is demonstrated, and the resonate modes of a 2.4 GHz Wi-Fi patch antenna at different frequencies are clearly observed. The experiments of a TM01 mode antenna verify the full polarization diagnosis ability of the method, and the linear polarization component is measured with the help of a polarization grid. The demonstrated diagnosis method has the advantages of high efficiency, ultraclose measurement distance, and superresolution and provides a highly promising and widely available method for antenna diagnosis.