Waveguide Line Research Articles

Miniaturization of microwave planar circuits using composite microstrip/coplanar-waveguide transmission lines

The rapid development of modern communication systems propels the demand of high performance and miniaturization of RF/microwave components. Power dividers and filters are indispensable circuit components in amplifiers and antenna feed-networks which occupy large footprint of circuit broads, particularly at low frequency. The purpose of this study is to initiate a new type of planar transmission line with unique dual signal-path characteristics and ultimately achieve circuit miniaturization. In this paper, a novel technique of consolidating microstrip lines (MLs) and coplanar waveguide (CPW) lines on a single dielectric substrate, designated as the composite microstrip/CPW line (CM/CPW line), is proposed. With reference to the average line length of ML and CPW, it warrants a physical length reduction of 48.3% and further achieves a reduction of 80.8% after zigzagging CM/CPW line. The proof-of-concept design example of a two-way Wilkinson power divider (WPD) has demonstrated the effectiveness of the miniaturization technique. The simulation, in combination with the experimental results, validates that a size reduction factor of 86.9% when compared to conventional one has been achieved while maintaining a fractional bandwidth of 57.7% for the WPD.

Microwave Detection Using Two-Atom-Thick Self-Switching Diodes Based on Quantum Simulations and Advanced Circuit Models

In this article, a two-atom-thick diode based on 2-D materials is presented for microwave detection. The diode consists of a molybdenum disulfide monolayer/graphene monolayer heterojunction transferred onto a silicon/silicon dioxide substrate and patterned by means of nanolithography techniques to obtain a geometrical self-switching diode. The interaction between the two monolayers gives rise to a double-stage device, which behaves as a back-to-back diode in the [−3, +3] V voltage range, and as a tunnel diode when exceeding +10 V. The heterojunction can be reproduced at the wafer scale, thanks to its CMOS compatibility and ease of fabrication, and it can be used efficiently as a microwave detector up to 10 GHz, with the best performance around the ISM 2.45-GHz band. Starting from advanced quantum simulations to predict the dc behavior of the single heterojunction-based channel, the diode was fabricated and fully characterized experimentally. Lastly, a rigorous equivalent circuit model is provided, which relies on the measured scattering parameters at high frequencies and allows treating the diode embedded into a coplanar waveguide line as a two-port lossy device. This way, the device can be exploited in circuit-based numerical tools for the design of complex microwave front ends.

Slot Line Waveguide Induced Magnetization Dynamics of Perpendicularly Magnetized La-YIG Thin Film

We study the magnetization dynamics in La-doped yttrium iron garnet thin film induced by a slot line waveguide with the magnetic field applied perpendicular to the plane. The magnetization dynamics depend significantly on the slot line waveguide dimensions, particularly the number of excitation conditions increases with the enlargement of linewidth and the gap between the lines. Such an increase is not observed when the magnetic field is applied to the film plane. The excitation is caused by the interaction between the local magnetization dynamics around the line and the spin waves coming from the other side of the line. Forward volume magnetostatic spin waves are emitted when the magnetic field is applied perpendicular to the film. Their magnetic field dependence of the wavelength change is very gradual, allowing the satisfaction of the resonance condition to be much easier than the in-plane magnetized film.

Control of spin waves by spatially modulated strain

We suggest using spatially modulated strain for control of a spin wave propagating inside a bulk magnet. The modulation with the wave vector $q=2k$, by virtue of magnetoelasticity, mixes spin waves with wave vectors near $k$ and $-k$. This leads to lifting the degeneracy of the symmetric and antisymmetric eigenstate combinations of these waves. The resulting picture reminds one of a tunneling particle in a symmetric double-well potential. Here, a moving spin wave being subjected to the $2k$-lattice modulation after some time alters its propagation direction to the opposite one, and so on. The effect can be utilized for the control of the spin-wave propagation that can be useful for spintronic and magnonic applications. The control may include a delay line element, filtering, and waveguide of the spin waves.

H-Band Broadband Balanced Power Amplifier in 250-nm InP HBT Technology Using Impedance-Transforming Balun

A broadband power amplifier in a 250-nm InP HBT technology is presented, working at full <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -band (220–320 GHz). A cascode transistor is employed as a power cell to achieve high gain and power at <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -band. Two-stage cascode power amplifier is designed with input and output impedance of not 50 but 25 Ω, reducing the impedance transformation ratio and allowing the broadband matching networks. Two power-amplifier channels are power-combined using on-chip baluns which performs the impedance transformation from 25 to 50 Ω. The balun operation is based on the electromagnetic field conversion between coplanar waveguide and microstrip line. It does not rely on long transmission lines with frequency-dependent length, so that it occupies a very compact area and exhibits a broadband performance. It also enables power amplifiers to operate in the balanced mode, allowing the area reduction and stable operation. Substrate modes and in-band resonances in InP substrate, which seriously degrade circuit performance and limits bandwidth, are effectively suppressed by the reduced on-chip ground and balanced operation. The fabricated power amplifier shows a measured small-signal gain of 20.8 dB at 232 GHz with a 3-dB bandwidth larger than 51 GHz (20.8%). Output power also exhibits a broadband performance of 8.0±1.5 dBm from 220 to 295 GHz with power gain larger than 10.5 dB, corresponding to a large-signal 3-dB bandwidth larger than 75 GHz. This belongs to an excellent bandwidth in both small- and large-signal performance among the reported <italic xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">H</i> -band power amplifiers.

A dual-beam lens-free slot-array antenna coupled high-T c superconducting fundamental mixer at the W-band

This paper presents a W-band high-T c superconducting (HTS) Josephson-junction fundamental mixer which is coupled using a dual-beam lens-free slot-array antenna. The antenna features a uniplanar six-element slot array fed by an ungrounded coplanar waveguide line, of which each element is a long slot loaded by four rectangular loops. Highly directional radiation is therefore realized by utilizing the long slots and array synthesis to form a relatively large antenna aperture. The antenna also enables asymmetric dual-beam radiation in opposite directions, which not only reduces the RF coupling losses but greatly facilitates the quasi-optics design for the integration of the HTS mixer into a cryocooler. The electromagnetic simulations show that a coupling efficiency as high as −2.2 dB, a realized gain of 13 dB and a front-to-back ratio of 10 dB are achieved at the frequency of 84 GHz. Using this on-chip antenna, a W-band HTS fundamental mixer module is experimentally developed and characterized for different operating temperatures. The measured conversion gain is −10 dB at 20 K and −14.6 dB at 40 K, respectively. The mixer noise temperature is predicted to be around 780 K at 20 K and 1600 K at 40 K, respectively. It is also analyzed that the mixer performance can be further improved if the Josephson junction parameters were optimized.

Efficient electromagnetic transducers for spin-wave devices

This paper presents a system-level efficiency analysis, a rapid design methodology, and a numerical demonstration of efficient sub-micron, spin-wave transducers in a microwave system. Applications such as Boolean spintronics, analog spin-wave-computing, and magnetic microwave circuits are expected to benefit from this analysis and design approach. These applications have the potential to provide a low-power, magnetic paradigm alternative to modern electronic systems, but they have been stymied by a limited understanding of the microwave, system-level design for spin-wave circuits. This paper proposes an end-to-end microwave/spin-wave system model that permits the use of classical microwave network analysis and matching theory towards analyzing and designing efficient transduction systems. This paper further compares magnetostatic-wave transducer theory to electromagnetic simulations and finds close agreement, indicating that the theory, despite simplifying assumptions, is useful for rapid yet accurate transducer design. It further suggests that the theory, when modified to include the exchange interaction, will also be useful to rapidly and accurately design transducers launching magnons at exchange wavelengths. Comparisons are made between microstrip and co-planar waveguide lines, which are expedient, narrowband, and low-efficiency transducers, and grating and meander lines that are capable of high-efficiency and wideband performance. The paper concludes that efficient microwave-to-spin-wave transducers are possible and presents a meander transducer design on YIG capable of launching varvec{lambda = 500},nm spin waves with an efficiency of − 4.45 dB and a 3 dB-bandwidth of 134 MHz.

Triple Band Compact Monopole Antenna for Applications Like Bluetooth, WiMAX and WLAN

In this work, a novel triband antenna is developed for wireless local area network (WLAN), worldwide interoperability for microwave access (WiMAX), and Bluetooth application. The proposed antenna is printed on a low-cost FR-4 substrate and has an overall size of 25 mm × 40 mm × 1.6 mm. Coplanar waveguide (CPW) line with characteristic impedance of 50 Ω is used as feed for the designed antenna. A prototype of this antenna is fabricated and tested to validate the simulation results. The measured result shows that the antenna has the triple-band response with frequency bands that correspond to S11<−10 dB 2.36 − 3.17, 3.8 − 4.35, and 5.69 − 6.02 GHz. The measured gains of the antenna at resonant frequencies of 2.61, 4.115 and 5.85 GHz are 0.756, 0.925 and 1.589 dBi, respectively. Maximum decrement in measured gain is only 0.671 dB which is attributed to losses from connectors and cables. A novel approach, based on a combination of a cap-shaped ground plane and gap coupling technique in the form of an interdigital capacitor (IDC), is used to achieve the characteristic of triple frequency bands. Finally, the utility of the proposed antenna is checked with a four-element MIMO antenna.

Modeling of Semiconductor Substrates for RF Applications: Part II—Parameter Impact on Harmonic Distortion

This article presents the accurate modeling results of the nonlinear behavior of a wide range of silicon-based substrates at RF. The TCAD-based model includes carrier inertia effects and captures the transient nonequilibrium phenomena in the semiconductor substrate regions in response to a large-amplitude RF signal. The model is applied to coplanar waveguide (CPW) lines measured on 19 different silicon-based samples that have key differences in their material and interface parameters, such as different values for nominal doping, interface oxide charge, the presence or not of a trap-rich passivation layer, and characteristic dimensions. Furthermore, the CPW line's distortion levels are measured from 25 °C up to 175 °C and at five fundamental frequencies under large-signal excitation from 50 MHz to 5.4 GHz. An excellent model to experiment correlation is achieved under all of these conditions, and the impact of the material and excitation parameters are discussed with strong physical insight provided by the simulation tool.

A low-cost invasive microwave ablation antenna with a directional heating pattern

Microwave ablation (MWA) is a cancer treatment method. The tumor tissue absorbs electromagnetic energy, which heats and kills it. A microwave ablation antenna plays a critical role in this process. Its radiation field must completely cover the tumor but not the healthy tissue. At present, the radiation pattern of most invasive ablation antennas is spherical. However, in the clinic, the shape of some tumors may be asymmetrical or the antenna cannot be inserted into the center of the tumor for some other reason. In order to solve these problems, a directional heating antenna for microwave ablation is proposed in this paper. The proposed antenna, operating at 2.45 GHz, consists of a monopole and a reflector. The feed is given by a substrate integrated coaxial line (SICL) and coplanar waveguide (CPW). The omnidirectional radiation field of the monopole is reflected by a reflector that is extended from the outer conductors of the SICL to form a directional radiation field. The impedance matching network is designed on SICL to match the antenna to 50 Ω. The antenna is fabricated using a mature printed circuit board (PCB). The reflection coefficient of the antenna in porcine liver tissue measured by a vector network analyzer shows good agreement with the simulations. Then, an ablation experiment in porcine liver is conducted with power of 10 W for 10 min, and the experimental results confirm the validity of the design.

The end‐fire Vivaldi antenna based on spoof surface plasmon polaritons

AbstractThis letter proposes an end‐fire Vivaldi antenna based on spoof surface plasmon polaritons (SPPs). SPP is generated by a periodic corrugated metal–insulator–metal (CMIM) waveguide on which the odd mode of the SPP is propagated and is rarely used in the design of antenna transmission lines. Gradient corrugations and slotlines form the transitional part to achieve momentum matching and impedance matching between the microstrip feed line and plasma waveguide. In addition, one parasitic patch is introduced in flare aperture to improve the performance of the radiation. Both the simulation and measured results are carried out and match well with the theoretical design. This antenna generates end‐fire radiation beams within 4‐9 GHz frequency range (S11 &lt; –10 dB). Measured results show that the realized gain is higher than 8.87 dB and the 3 dB beam width is stable between 31 and 36° over the operation frequency.

Cost-Effective Surface-Mount Off-Center-Fed Dipole Antenna Element and Its Array for 5G Millimeter Wave New Radio Applications

A cost-effective ball grid array (BGA) packaged surface-mount off-center-fed dipole antenna element and its array are proposed for 5G millimeter-wave new radio (NR) applications. The proposed antenna element exhibits a compact size of 0.61 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.61 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.16 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ( λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> is the wavelength in free space at the center operating frequency) and is realized by only one FR4 layer to minimize cost. Plated through holes (PTHs) connect the dipole patch on the top layer to the bottom layer. Furthermore, tin-lead solder balls are mounted under the bottom layer to form the BGA packaging. The surface-mountable feature enables the antenna element to be integrated with other surface mount devices without any waveguide or coaxial connectors. The evaluation board uses a 50- Ω grounded coplanar waveguide (GCPW) line to test the performance of the antenna element and array. The antenna prototype and evaluation board have been manufactured and measured. The measurement results show that the -10-dB impedance bandwidth of the proposed antenna element achieves 35.7% in the range of 25.1-36 GHz. The measured peak gains of the antenna element and the 1 ×8 arrays are 6.72 and 13.53 dBi, respectively.

A Survey: Slot Antenna and Antenna Array.

Slots are generally introduced in the antenna or antenna to improve the impedance matching, improve the bandwidth, and gain. Sometimes slots are introduced in the ground planes, or between antenna elements to reduce the mutual coupling between elements. The antenna being an important element in wireless communication technology, the design of the same with different requirements is important. This paper gives the survey of the slot antenna and antenna array constructed through waveguide and microstrip lines, to meet different antenna parameters as required in various wireless communication technology.

A Linear Microwave Plasma Source Using a Circular Waveguide Filled with a Relatively High-Permittivity Dielectric: Comparison with a Conventional Quasi-Coaxial Line Waveguide

For a conventional linear microwave plasma source (LMPS) with a quasi-coaxial line transverse electromagnetic (TEM) waveguide, a linearly extended plasma is sustained by the surface wave outside the tube. Due to the characteristics of the quasi-coaxial line MPS, it is easy to generate a uniform plasma with radially omnidirectional surfaces, but it is difficult to maximize the electron density in a curved selected region. For the purpose of concentrating the plasma density in the deposition area, a novel LMPS which is suitable for curved structure deposition has been developed and compared with the conventional LMPS. As the shape of a circular waveguide, it is filled with relatively high-permittivity dielectric instead of a quasi-coaxial line waveguide. Microwave power at 2.45 GHz is transferred to the plasma through the continuous cylindrical-slotted line antenna, and the radiated electric field in the radial direction is made almost parallel to the tangential plane of the window surface. This research includes the advanced 3D numerical analysis and compares the results with the experiment. It shows that the electron density in the deposition area is higher than that of the conventional quasi-coaxial line plasma MPS.

Study of Nanowire-Based Integrated via Technology for CMOS Application in Millimeter-Wave Frequencies

This work shows a novel integrated via structure based on 1.2- μm thick copper nanowires (NWs) for use in CMOS applications at millimeter-wave frequencies. Coplanar waveguide (CPW) lines are fabricated on a 5000-Ω-cm high-resistivity silicon wafer and connected by NW vias that are grown in integrated anodized alumina oxide (AAO). The AAO layer is fabricated by anodizing an evaporated aluminum layer onto the silicon wafer. This cointegrated technology has 0.095-dB insertion loss for 0.3-mm long circuits with two vias at 40 GHz. The results are promising with an estimated loss per via of approximately 0.0275 dB. The fabricated structure shows great performance agreement with its reference test circuits of similar length. The design comparisons of circuits with different via dimensions and positions show that the shorter the via length, the wider the via width; and placing the via on the CPW ground plane closer to the signal line provides better performance.

A terahertz on-chip InP-based power combiner designed using coupled-grounded coplanar waveguide lines* *Project supported in part by the National Natural Science Foundation of China (Grant No. 61871072).

This article presents the design and performance of a terahertz on-chip coupled-grounded coplanar waveguide (GCPW) power combiner using a 50μm-thick InP process. The proposed topology uses two coupled-GCPW lines at the end of the input port to substitute two quarter-wavelength GCPW lines,which is different from the conventional Wilkinson power combiner and canavailably minimize the coverage area. According to the results obtained, forthe frequency range of 210–250z, the insertion losses for each two-waycombiner and four-way combiner were lower than 1.05 dB and 1.35 dB,respectively, and the in-band return losses were better than 11 dB. Moreover,the proposed on-chip GCPW-based combiners achieved a compromise in low-loss, broadband, and small-size, which can find wide applications in terahertz bands, such as power amplifiers and signal distribution networks.

Basic Principles of Microwave Communication

Microwave is a form of electromagnetic radiation with one meter to the one-millimeter range. It has the excellent capacity to carry a lot of information and is a good choice to deal with data crisis. It can be used in many fields, and the development of microwave technology is being studied extensively. Microwaves can be used in scientific research, and the structure of the internal substances can be analyzed according to the different degrees of microwave absorption by different substances. Also, the microwave physiotherapy instrument created by microwave technology can kill some diseased cells and play a therapeutic role. This thesis will discuss and introduce some basic knowledge and equipment of transmission line theory, waveguide theory and microwave chemistry, to have a basic understanding of microwave technology. The results show that microwaves should have optical characteristics, skin effects, and other properties. Antennas, radars, transmission lines, and remote sensing measurement applications are all related to these characteristics

Time Refraction of Spin Waves.

We present an experimental study of time refraction of spin waves (SWs) propagating in microscopic waveguides under the influence of time-varying magnetic fields. Using space- and time-resolved Brillouin light scattering microscopy, we demonstrate that the broken translational symmetry along the time coordinate results in a loss of energy conservation for SWs and thus allows for a broadband and controllable shift of the SW frequency. With an integrated design of SW waveguide and microscopic current line for the generation of strong, nanosecond-long, magnetic field pulses, a conversion efficiency up to 39% of the carrier SW frequency is achieved, significantly larger compared to photonic systems. Given the strength of the magnetic field pulses and its strong impact on the SW dispersion relation, the effect of time refraction can be quantified on a length scale comparable to the SW wavelength. Furthermore, we utilize time refraction to excite SW bursts with pulse durations in the nanosecond range and a frequency shift depending on the pulse polarity.

A 90 GHz SINIS Detector With 2 GHz Readout

A superconductor-insulator-normal metal-insulator-superconductor (SINIS) detector integrated in a planar 90 GHz band twin-slot antenna with a 2 GHz superconducting resonator readout was fabricated and experimentally studied. In order to achieve high pixel count, the traditional dc readout of the SINIS detector is replaced by NbN coplanar 13.850 mm long superconducting resonator. SINIS detectors have traditionally dc Junction Field Effect Transistor (JFET) room-temperature readout. Such readout requires individual wiring for each pixel, while the microwave readout is far less cluttered as only one coaxial line is needed for hundreds of devices. Such readout operates similar to frequency domain multiplexing (FDM) for microwave kinetic inductance detectors (MKID). The planar twin slot antenna has two parallel slots in a metal ground plane which are excited coherently by short sections of a coplanar waveguide (CPW) line with a SINIS detector at the center. One section of the CPW is extended past the slot in a long superconducting section which functions as a quarter wavelength resonator. This resonator is short circuited to the ground plane at the far end, with the expected open circuited end terminated by the SINIS detector in the antenna. We measured the response of sample to black body radiation temperatures 6 K and 9 K. The corresponding dynamic resistance maximum drops from 50 kΩ down to 30 kΩ. An RF readout channel comprising a coplanar coupler and a coplanar resonator has a resonant frequency of 1.8 GHz. Unloaded Q factor (without incoming irradiation) is 200. The signal spectral characteristics and the response to the black body radiation have shown design values as expected.

Multidisciplinary optimization of the waveguide transmission line for ITER HFS reflectometry

The research is devoted to the application of parametric optimization methods to the design of the waveguide line of ITER High Field Side Reflectometry (HFSR) diagnostic system. This waveguide line in the Interspace and Port Cell zones, on the one hand, must provide enough flexibility of the structure to withstand interface mechanical loads, and on the other hand, must ensure low signal losses. In order to satisfy these two contradicting requirements, an optimization problem was formulated and solved. Two different parametric optimization algorithms were used in conjunction with MATLAB and ANSYS software to find a reasonable design of the HFSR waveguide. MATLAB was used to construct the bend path with the minimal signal losses, and ANSYS was used to calculate the mechanical response of the constructed waveguide to the applied loads.