Microwave Circuitry Research Articles

Interconnect for Dense Electronically Scanned Antenna Array Using High-Speed Vertical Connector.

We present the design and the performance evaluation of a new interconnect for large-scale densely packed electronically scanned antenna arrays that utilize a high-speed digital board-to-board vertical connector. The application targets microwave tissue, imaging in the frequency range from 3 GHz to 8 GHz. The tissue-imaging arrays consist of hundreds of active antenna elements, which require low-reflection, low-loss, and low-crosstalk connections to their respective receiving and transmitting circuits. The small antenna size and the high array density preclude the use of coaxial connectors, which are also expensive and mechanically unreliable. Modern board-to-board high-speed connectors promise bandwidths as high as 12 GHz, along with high pin density, mechanical robustness, and low cost. However, their compatibility with the various transmission lines leading to/from the miniature printed antenna elements and microwave circuitry is not well studied. Here, we focus on the design of the transitions from coplanar waveguide transmission lines to/from a high-speed vertical connector. The performance of the interconnect is examined through electromagnetic simulations and measurements. Comparison is carried out with the expensive sub-miniature push-on sub-micro coaxial connectors commonly used in miniature radio-frequency electronics. The results demonstrate that high-speed vertical connectors can provide comparable performance in the UWB frequency range.

Tunable capacitor for superconducting qubits using an InAs/InGaAs heterostructure

Adoption of fast, parametric coupling elements has improved the performance of superconducting qubits, enabling recent demonstrations of quantum advantage in randomized sampling problems. The development of low loss, high contrast couplers is critical for scaling up these systems. We present a blueprint for a gate-tunable coupler realized with a two-dimensional electron gas in an InAs/InGaAs heterostructure. Rigorous numerical simulations of the semiconductor and high frequency electromagnetic behavior of the coupler and microwave circuitry yield an on/off ratio of more than one order of magnitude. We give an estimate of the dielectric-limited loss from the inclusion of the coupler in a two qubit system, with coupler coherences ranging from a few to tens of microseconds.

Solid-State Microwave Magnetometer with Picotesla-Level Sensitivity

Magnetometry with diamond nitrogen-vacancy (NV) ensembles has enabled devices with picotesla sensitivity at static and low-frequency fields, but their performance at higher frequencies lags far behind. The authors solve the technical challenges and demonstrate a microwave-frequency NV magnetometer with picotesla sensitivity, by implementing a pulse scheme for noise cancellation and employing a custom-grown diamond. This sensitivity enhancement could be extended into a far broader range of frequencies using spin-locking and quantum frequency mixing. These results could lead to applications such as near-field antenna characterization and microwave circuitry imaging.

Classification of rat mammary carcinoma with large scale in vivo microwave measurements

Mammary carcinoma, breast cancer, is the most commonly diagnosed cancer type among women. Therefore, potential new technologies for the diagnosis and treatment of the disease are being investigated. One promising technique is microwave applications designed to exploit the inherent dielectric property discrepancy between the malignant and normal tissues. In theory, the anomalies can be characterized by simply measuring the dielectric properties. However, the current measurement technique is error-prone and a single measurement is not accurate enough to detect anomalies with high confidence. This work proposes to classify the rat mammary carcinoma, based on collected large-scale in vivo S_{11} measurements and corresponding tissue dielectric properties with a circular diffraction antenna. The tissues were classified with high accuracy in a reproducible way by leveraging a learning-based linear classifier. Moreover, the most discriminative S_{11} measurement was identified, and to our surprise, using the discriminative measurement along with a linear classifier an 86.92% accuracy was achieved. These findings suggest that a narrow band microwave circuitry can support the antenna enabling a low-cost automated microwave diagnostic system.

Multiband Reconfigurable Antennas for 5G Wireless and CubeSat Applications: A Review

The rapid development of wireless technology has sparked interest in multi-band reconfigurable antennas as devices and satellites are innovating toward miniaturization. With limited space, reliable and efficient high bandwidth antenna systems are needed for current and next-generation wireless technology as well as for the revolutionary small satellites. The fifth generation of mobile communication technology promises high data rates, low latency and good spectrum efficiency. One of the key enablers of this technology is the integration of satellite technology-particularly CubeSats with terrestrial communication technologies. Next-generation antennas that can meet functional requirements for 5G and CubeSat applications are therefore of fundamental importance. These antenna systems should have large bandwidth, high gain and efficiency and be compact in size. Reconfigurable antennas can provide different configurations in terms of the operating frequency, radiation pattern and polarization. Tuning reconfigurable antennas can be done by changing the physical parameters of the antenna elements through electronic switches, optical switches and the use of meta-materials. The most popular implementation method for reconfigurable antennas for wireless and satellite communication is the electronic switching method due to its high reliability, efficiency, and ease of integration with microwave circuitry. In this article, different techniques for implementing reconfigurable and multi-band antennas are reviewed, with emphasis on two main application areas; 5G wireless communication and CubeSat application. Different reconfiguration techniques have been studied for application in various wireless communication systems such as satellite communication, multiple-input multiple-output (MIMO) systems, cognitive radio and 5G communication. It has been found that reconfigurable antennas have favourable properties for next-generation wireless technology and small satellites. These properties include low cost, less volume requirements and good isolation between wireless standards.

Structurally Integrated Radar in an Aerospace Composite Laminate

This article presents a fabrication method for a <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$C$ </tex-math></inline-formula> -band, low-power, frequency-modulated continuous wave (FMCW) radar front–end technology demonstrator that is fully embedded in a representative aerospace composite structure. This demonstrator uses a structural glass-fiber-reinforced polymer laminate as both the mechanical load-bearing element and the multilayer substrate for the integrated microwave circuitry. The system design and optimization have been described in detail. The electromagnetic simulation of the technology demonstrator was shown to be in excellent agreement with the measurement results. Finally, the FMCW radar front-end was tested as a complete system and shown to yield correct distance-to-target estimations. The demonstrated integration technique will lead to smart skins where electronic circuits and complete systems are embedded in load-bearing composite structures to yield truly multifunctional capabilities.

An impedance matched interdigital capacitor at 1.5 GHz for microfluidic sensing applications

In this paper, a novel microwave sensor is realized by double stub matching a deionized (DI) water loaded interdigital capacitor to 50 Ω to create a minimum in reflection coefficient around 1.5 GHz. Glucose, l-proline and glycine solutions with different concentrations are loaded into the sensor and consequently impact the frequency of the minimum reflection coefficient. The proposed sensor achieves a linear correlation between its minimum reflection coefficient frequency and permittivity of the loaded solutions. Mixtures between fetal bovine serum (FBS) and phosphate-buffered saline (PBS) having FBS volume fractions of 0%, 20 %, 40 %, 60 %, 80 % and 100 % are also loaded into the proposed sensor. A linear relationship between the volume fractions of the loaded mixtures and the minimum reflection coefficient frequency point of the proposed sensor is as well achieved. Measurement results demonstrate the potential of the proposed miniaturized sensor, coupled with the dislocated-of-the-chip and space-consuming supporting microwave circuitry, for applications such as sample preparation at the microfluidic scale.

A dielectric resonator based line stripe miniaturized ultra‐wideband antenna for fifth‐generation applications

SummaryThis work presents an original dielectric resonator based line stripe miniature ultra‐wideband (UWB) antenna for 5G applications. The length, width, and height of the designed antenna are 23, 15, and 1.605 mm, respectively. The projected antenna prototype is composed of a simple line structure‐based modified scattered patch and a rectangular ground plane consisting of a saw tooth orientation in the upper end. A number of rectangular resonators are placed on both sides of the patch and ground to optimize the desired results. This technique ensures the lower operating band and made a significant improvement of efficiency without compromising the antenna size. The proposed design obtained the range of frequency bandwidth from 3.55 to 4.2 GHz under the −10‐dB scale, which covers the lower fifth‐generation (5G) communication band offered by Federal Communications Commission (FCC). The moderate gain and more than 80% radiation efficiency at a resonant point with strong fidelity factor confirms the usability and lower signal distortion of the antenna. The design offers an omnidirectional radiation pattern with 90° elevated directivity for cross polarization. This proposed design is compact in size and can be integrated into limited space around microwave circuitry with low manufacturing cost. The performance parameters like operating bandwidth, antenna size, and area of application, dielectric constant, fractional bandwidth, and omnidirectional radiation pattern were proposed as a suitable candidate for 5G application.

Three Different Compact Elliptical Slot Ultra -Wide band Antennas for Wireless Communication Applications

From this current paper, 3 separate elliptical slotted ultra- wide band (UWB) antennas are being proposed. These antennas have been designed with a standard PCB design process to be capable of integrating with radiofrequency or microwave circuitry. Two designs were presented in which the initial design comprised a half circular ring radiator and the remaining one considers a half elliptical ring radiator. The third design of the radiator is in the shape of a crescent. The impedance bandwidth of all these presented antenna designs varies from 2.5GHz and reaches to 14GHz with a S11 less than -10GHz. Here, every proposed antenna design also has a consistent radiation pattern across its frequency band of interest. The performance of the antenna is impressive for lower band frequency in UWB system, which differs in a range of 3.1GHz to 5.1GHz. Across the whole frequency band the antenna shows a 10db return loss bandwidth. The antenna is fabricated on RT-duroid substrate and fed with 50 Ω coupled tappered transmission line.

A 3.5-GHz pseudo-correlation type radiometer for biomedical applications

A pseudo-correlation type radiometer based on astrophysical instrumentation is proposed for biomedical applications. The working frequency band is centred at 3.5 GHz. The prototype performance and functionality are assessed. The theoretical analysis of the receiver topology is described, as well as the subsystems employed in its configuration, such as a customized on-body antenna and microwave circuitry based on off-the-shelf devices. Experimental characterization of the individual subsystems and preliminary measurements of the radiometer prototype are presented. Furthermore, customized phantoms, based on polyvinyl alcohol cryogel, are employed for the characterization of the on-body antenna, as well as the radiometer.

Optical-vibration and intrinsic dielectric properties of low-k high-Q Zn2GeO4 ceramics

Polycrystalline Zn2GeO4 powders and sintered ceramics were prepared by the microwave–assisted solid-state reaction method. Structural, chemical, and morphological properties, as well as the optical-vibration features of the obtained materials, were investigated by XRD, scanning and transmission electron microscopies, polarized micro-Raman scattering, and infrared spectroscopy. Single-phase, high-purity, crystalline powders and ceramics belonging to the rhombohedral R3‾ space group showed excellent polarized Raman response, which allowed us to determine and assign 39 gerade phonons out of the 42 optical modes predicted for Zn2GeO4 by group theory. Also, the 29 most relevant polar phonons (ungerade) of the sintered material were revealed and the dielectric strengths of the modes that contribute to the dielectric response were obtained. The infrared dispersion parameters allowed us to calculate the extrapolated dielectric constants ε0 = 7.02 and ε∞ = 2.41, and an intrinsic quality factor Qu × f = 187 THz, at 10 GHz, values that are quite suitable for applications as low-k high-Q materials in microwave circuitry. The very comprehensive set of phonon modes obtained here should be useful for understanding the behavior of the material, needed to improve their already numerous optical applications (luminescence, photocatalysis).

Polarized Raman scattering and infrared dispersion analysis of Na2ZnGeO4 ceramics

AbstractThe structural, chemical, morphological, and optical‐vibration properties of Na2ZnGeO4 ceramic samples prepared by conventional solid‐state processing and sintered at 1,100°C are investigated in detail. X‐ray diffraction (XRD), scanning electron microscopy (SEM), transmission electron microscopy (TEM), energy dispersive spectroscopy (EDS), and electron energy‐loss spectroscopy (EELS) showed that single‐phase samples belonging to the monoclinic Pn (= ) space group were obtained. Optical‐vibration investigations by polarized Raman and infrared spectroscopies altogether allowed us to present the characteristic features of the relevant polar phonons of the material, for the first time. Twenty‐nine out of the 45 optical modes predicted for Na2ZnGeO4 by group theory were determined, and their symmetries are revealed. The dielectric strengths of the modes that contribute to the dielectric response were obtained. Besides, the infrared dispersion parameters allowed us to calculate the extrapolated dielectric constants ε0 = 7.62 and ε∞ = 2.80, and an intrinsic quality factor Qu × f = 154 THz, at 10 GHz. The obtained values show that this material can be classified as a low‐k high‐Q ceramics, which potential applications in microwave circuitry.

Reconfigurable Antennas: Switching Techniques—A Survey

Due to the fast development of wireless communication technology, reconfigurable antennas with multimode and cognitive radio operation in modern wireless applications with a high-data rate have drawn very close attention from researchers. Reconfigurable antennas can provide various functions in operating frequency, beam pattern, polarization, etc. The dynamic tuning can be achieved by manipulating a certain switching mechanism through controlling electronic, mechanical, physical or optical switches. Among them, electronic switches are the most popular in constituting reconfigurable antennas due to their efficiency, reliability and ease of integrating with microwave circuitry. In this paper, we review different implementation techniques for reconfigurable antennas. Different types of effective implementation techniques have been investigated to be used in various wireless communication systems such as satellite, multiple-input multiple-output (MIMO), mobile terminals and cognitive radio communications. Characteristics and fundamental properties of the reconfigurable antennas are investigated.

Microwave signal switching on a silicon photonic chip

Microwave photonics uses light to carry and process microwave signals over a photonic link. However, light can instead be used as a stimulus to microwave devices that directly control microwave signals. Such optically controlled amplitude and phase-shift switches are investigated for use in reconfigurable microwave systems, but they suffer from large footprint, high optical power level required for switching, lack of scalability and complex integration requirements, restricting their implementation in practical microwave systems. Here, we report Monolithic Optically Reconfigurable Integrated Microwave Switches (MORIMSs) built on a CMOS compatible silicon photonic chip that addresses all of the stringent requirements. Our scalable micrometer-scale switches provide higher switching efficiency and require optical power orders of magnitude lower than the state-of-the-art. Also, it opens a new research direction on silicon photonic platforms integrating microwave circuitry. This work has important implications in reconfigurable microwave and millimeter wave devices for future communication networks.

Multilayer ion trap with three-dimensional microwave circuitry for scalable quantum logic applications

We present a multilayer surface-electrode ion trap with embedded 3D microwave circuitry for implementing entangling quantum logic gates. We discuss the electromagnetic full-wave simulation procedure that has led to the trap design and the characterization of the resulting microwave field-pattern using a single ion as a local field probe. The results agree with simulations within the uncertainty; compared to previous traps, this design reduces detrimental AC Zeeman shifts by three orders of magnitude. The design presented here can be viewed as an entangling gate component in a library for surface-electrode ion traps intended for quantum logic operations.

Toroidal metasurface resonances in microwave waveguides

We theoretically investigate the possibility to load microwave waveguides with dielectric particle arrays that emulate the properties of infinite, two-dimensional, all-dielectric metasurfaces. First, we study the scattering properties and the electric and magnetic multipole modes of dielectric cuboids and identify the conditions for the excitation of the so-called anapole state. Based on the obtained results, we design metasurfaces composed of a square lattice of dielectric cuboids, which exhibit strong toroidal resonances. Then, three standard microwave waveguide types, namely parallel-plate waveguides, rectangular waveguides, and microstrip lines, loaded with dielectric cuboids are designed, in such a way that they exhibit the same resonant features as the equivalent dielectric metasurface. The analysis shows that parallel-plate and rectangular waveguides can almost perfectly reproduce the metasurface properties at the resonant frequency. The main attributes of such resonances are also observed in the case of a standard impedance-matched microstrip line, which is loaded with only a small number of dielectric particles. The results demonstrate the potential for a novel paradigm in the design of “metasurface-loaded” microwave waveguides, either as functional elements in microwave circuitry, or as a platform for the experimental study of the properties of dielectric metasurfaces.

Multiplexed readout of four qubits in 3D circuit QED architecture using a broadband Josephson parametric amplifier

We propose and demonstrate a frequency-multiplexed readout scheme in 3D circuit-quantum electrodynamics (cQED) architecture. We use four transmon qubits coupled to individual rectangular cavities which are aperture-coupled to a common rectangular waveguide feedline. A coaxial to waveguide transformer at the other end of the feedline allows one to launch and collect the multiplexed signal. The reflected readout signal is amplified by an impedance-engineered broadband parametric amplifier with 380 MHz bandwidth. This provides us high fidelity single-shot readout of multiple qubits using compact microwave circuitry, an efficient way for scaling up to more qubits in 3D cQED.

Multilayer ion trap technology for scalable quantum computing and quantum simulation

We present a novel ion trap fabrication method enabling the realization of multilayer ion traps scalable to an in principle arbitrary number of metal-dielectric levels. We benchmark our method by fabricating a multilayer ion trap with integrated three-dimensional microwave circuitry. We demonstrate ion trapping and microwave control of the hyperfine states of a laser cooled 9Be+ ion held at a distance of 35 above the trap surface. This method can be used to implement large-scale ion trap arrays for scalable quantum information processing and quantum simulation.

Multilayer protective coatings obtained by pulsed laser deposition

Devices developed for the aeronautic or space industries must be able to operate in harsh environments. In order to protect devices such as microstrip antennae, various coatings have to be used. Herein, we present the results of obtaining YSZ/Al2O3 heterostructures by Pulsed Laser Deposition (PLD) for the protection of planar monopole antennas without changing their performances after the deposition process. The theoretical SRIM-TRIM simulation code results on the effects of ionized radiations incident on a YSZ/Al2O3 heterostructure, as well as the physical properties of the YSZ/Al2O3 thin films obtained by the PLD technique are also presented. The SRIM studies show that at the same energy range the proton penetration depth is higher than the alpha penetration depth, giving insights about the penetration depth of proton and alpha particles in the studied targets. Our goal is to obtain a multilayer structure able to enhance the endurance of the antenna and microwave circuitry in harsh space environment without reducing the performances under nominal operation conditions.

Multi-Band MIMO Antenna Design with User-Impact Investigation for 4G and 5G Mobile Terminals.

In this study, we propose a design of a multi-band slot antenna array applicable for fourth-generation (4G) and fifth-generation (5G) smartphones. The design is composed of double-element square-ring slot radiators fed by microstrip-line structures for easy integration with radio frequency (RF)/microwave circuitry. The slot radiators are located on the corners of the smartphone printed circuit board (PCB) with an overall dimension of 75 × 150 mm2. The proposed multiple-input multiple-output (MIMO) antenna is designed to meet the requirements of 4G and 5G mobile terminals with essential bandwidth for higher data rate applications. For −10 dB impedance bandwidth, each single-element of the proposed MIMO design can cover the frequency ranges of 2.5–2.7 GHz (long-term evolution (LTE) 2600), 3.45–3.8 GHz (LTE bands 42/43), and 5.00–5.45 GHz (LTE band 46). However, for −6 dB impedance bandwidth, the radiation elements cover the frequency ranges of 2.45–2.82 GHz, 3.35–4.00 GHz, and 4.93–5.73 GHz. By employing the microstrip feed lines at the four different sides of smartphone PCB, the isolation of the radiators has been enhanced and shows better than 17 dB isolation levels over all operational bands. The MIMO antenna is implemented on an FR-4 dielectric and provides good properties including S-parameters, efficiency, and radiation pattern coverage. The performance of the antenna is validated by measurements of the prototype. The simulation results for user-hand/user-head impacts and specific absorption rate (SAR) levels of the antenna are discussed, and good results are achieved. In addition, the antenna elements have the potential to be used as 8-element/dual-polarized resonators.