External Phase Shifter Research Articles

Substrate-Integrated Cylindrical Cavity Controlled Hexa-Polarization Flexible Cylindrical Dielectric Resonator Antenna for Ku-Band Applications

A substrate-integrated cylindrical cavity (SICC) fed polarization flexible cylindrical dielectric resonator antenna (CDRA) is presented in this literature. To excite the CDRA, a unique and simple feeding approach based on substrate-integrated waveguide (SIW) technology is demonstrated. This SICC is fed by two 50Ω microstrip lines, oriented orthogonally to each other. The SICC with a cross slot on its top metalized surface and the TM110 mode excites inside it act together to couple energy efficiently to the CDRA. Applying different phase combinations signals at the two input ports of the SICC, the CDRA can radiate in four different orientations linear polarization (LP) (along φ = 0°, 45°, −45°, and 90° ), left-handed circular polarization (LHCP), and right-handed circular polarization (RHCP). A conventional cylindrical dielectric resonator having relative permittivity ϵd = 10 is preferred. Its diameter, height, and cross-slot dimensions are optimized to operate the CDRA over Ku-band with 12% impedance bandwidth, 2-dB axial ratio (AR) bandwidth of 11%, and 3-dB gain bandwidth of 12%. In this operating band, CDRA resonates at three different higher-order modes (HEM32δ, HEM113, and HEM12δ+2) with 8 ± 1.6 dBi/dBic gain for all the polarization states. The measurements of this antenna are conducted using two external phase shifters and one power divider.

Design and simulation of phased array antenna 5G applications

Modern mobile communication faces challenges due to the limited frequency spectrum, driving the need for antennas that are simple, low-profile, and robust. Microstrip patch antennas and arrays are ideal choices due to their size, cost, and performance advantages. Polarization is crucial, especially in mobile and space communications, where antenna misalignment requires constant reorientation. Rectangular microstrip patch antennas can help mitigate signal loss and multipath effects in such scenarios. Phased array subsystems are becoming essential in next-generation mobile communication for their ability to electronically steer antenna beams without physical movement. Previous methods for rectangular microstrip patch radiation using orthogonal modes with a 90° time-phase difference resulted in poor axial ratio, gain, and return loss. These methods also used complex dual-feed excitation with an external 90° power divider and external phase shifters for beam steering. This paper proposes a simpler approach using a corner trimming technique for radiation and progressive phase excitations at source ports for phased arrays. The design and optimization for 26 GHz operation are achieved using simulation-based modeling software, ANSYS HFSS, on substrates like FR4 epoxy and Rogers RT or Duroid 5880. This paper includes the design and simulation of rectangular microstrip patches and 1x2 and 1x4 linear phased arrays to operate at 26 Ghz.

Combinatorial logic devices based on a multi-path active ring circuit.

In this work, we describe a logic device in which an act of computation is associated with finding a path connecting input and output ports. The device is based on an active ring circuit comprising electric and magnetic parts. The electric part includes an amplifier, a phase shifter, and an attenuator. The magnetic part is a multi-port magnetic matrix comprising delay lines and frequency filters. Signals propagating on different paths may accumulate different phase shifts. Auto-oscillations occur in the circuit when the magnetic and electric parts match each other to meet the resonance amplitude and phase conditions. The system naturally searches for a resonance path that depends on the position of the electric phase shifter and amplification level. The path is detected by the set of power sensors. The proposed logic device can be used for solving a variety of computational problems. We present the results of numerical modeling illustrating prime factorization and finding the shortest path connected selected points on the mesh. We also present experimental data on the proof-of-the-concept experiment for the two-path device. The magnetic part consists of two waveguides made of single-crystal yttrium iron garnet Y3Fe2(FeO4)3 (YIG) films. Different phase shifts per delay line are achieved by adjusting the magnitude and direction of the bias magnetic field. The auto-oscillation signal changes the propagation path in the magnetic matrix depending on the position of the outer electric phase shifter. The power difference between the active and passive paths exceeds 40 dBm at room temperature. The described logic devices are robust, deterministic, and operate at room temperature. The number of possible paths increases factorial with the size of the mesh. It may be possible to encode information in paths and retrieve it using the external phase shifters and attenuators. Potentially, combinatorial logic devices may compete with quantum computers in functional throughput. Physical limits and constraints are also discussed.

Prime factorization using coupled oscillators with positive feedback

Prime factorization is a procedure of determining the prime factors of a given number N that requires super-polynomial time for conventional digital computers. In this work, we describe an approach to prime factorization using coupled oscillators with positive feedback. The approach includes several steps, where some of the steps are accomplished on a general type computer, and some steps are accomplished using coupled oscillators. We present experimental data on finding the primes of N = 817. The experiment is performed on a system of two coupled active ring oscillators. Each of the oscillators possesses its own set of eigenfrequencies that can be independently controlled by the external phase shifter. The coupling allows us to check on any common frequency that leads to the phase lock-in and power increase in the circuit. One of the ring oscillators includes a spin wave magnetic delay line made of Y3Fe2(FeO4)3, while the second oscillator includes an ordinary coaxial cable as a delay line. There are 22 eigenfrequencies for the spin wave oscillator and 4 eigenfrequencies for the oscillator with coaxial cable in the frequency band of operation. It takes less than 10 μs for the system to find the common frequency (if any). The most appealing property of the proposed circuit is that the processing time does not scale with the number of eigenfrequencies. Potentially, circuits with coupled active ring oscillators can be utilized to solve a variety of computational problems.

Further compactifying linear optical unitaries

Quantum integrated photonics requires large-scale linear optical circuitry, and for many applications, it is desirable to have a universally programmable circuit, able to implement an arbitrary unitary transformation on a number of modes. This has been achieved using the Reck scheme, consisting of a network of Mach–Zehnder interferometers containing a variable phase shifter in one path as well as an external phase shifter after each Mach–Zehnder. It subsequently became apparent that with symmetric Mach–Zehnders containing a phase shifter in both paths, the external phase shifters are redundant, resulting in a more compact circuit. The rectangular Clements scheme improves on the Reck scheme in terms of circuit depth, but it has been thought that an external phase-shifter was necessary after each Mach–Zehnder. Here, we show that the Clements scheme can be realized using symmetric Mach–Zehnders, requiring only a small number of external phase-shifters that do not contribute to the depth of the circuit. This will result in a significant saving in the length of these devices, allowing more complex circuits to fit onto a photonic chip, and reducing the propagation losses associated with these circuits. We also discuss how similar savings can be made to alternative schemes, which have robustness to imbalanced beam-splitters.

Spin wave interference detection via inverse spin Hall effect

In this Letter, we present experimental data that demonstrate a spin wave interference detection using an inverse spin Hall effect (ISHE). Two coherent spin waves are excited in a yttrium-iron garnet waveguide by continuous microwave signals. The initial phase difference between the spin waves is controlled by the external phase shifter. The ISHE voltage is detected at a distance of 2 and 4 mm away from the spin wave generating antennas by an attached Pt layer. Experimental data show ISHE voltage oscillation as a function of the phase difference between the two interfering spin waves. This experiment demonstrates an intriguing possibility of using ISHE in a spin wave logic circuit converting a spin wave phase into an electric signal.

Planar Feeding Circuit Integrated With a Compact Dielectric Resonator for Polarization Diversity

A compact two-port feeding circuit that supports a dielectric resonator (DR) element is presented for applications requiring polarization diversity. The L-band structure consists of a cylindrical DR that can generate right-handed circular polarization (RHCP), left-handed circular polarization (LHCP), and linearly polarized radiation. The DR dimensions have been optimized considering a relative dielectric constant of ε <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">r</sub> = 27, and the entire structure (the circuit and DR) has dimensions of 9 cm ×9 cm ×2 cm (or about 0.3 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.3 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> ×0.07 λ <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">0</sub> at the lower operational frequency range). Radiation by the DR originates from four orthogonal HE <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">11δ</sub> modes that are excited by four radial slots etched out of the ground plane (all underneath the DR) printed on top of an FR-4 substrate. Each of these four slots is unconventionally driven by two 50- Ω microstrip lines, and all four radial slots conform to the shape of the top cylindrical DR element. Polarization diversity is achieved with this DR and circuit system (DRCS) arrangement, mainly by the design of its fully integrated and planar circuit, which routes power to the eight microstrip lines for DR excitation. This FR-4 printed circuit board (PCB) feeding system consists of two meandered Wilkinson power dividers, two 180° delay lines, and four surface mount 90° hybrid couplers. The complete DRCS is compact in size, is broadband (more than 40%), and offers the advantage of requiring only two external ports, one for LHCP the other for RHCP, while an external phase shifter and a combiner are needed for linearly polarized radiation.

Interference based square lattice photonic crystal logic gates working with different wavelengths

We propose a new configuration of interference based OR, XOR, NOT and AND optical logic gates on a two dimensional square lattice photonic crystal (PhC) platform. The working of these devices was analyzed by the FDTD method and the operating frequency range was explored using the plane wave expansion method. The XOR and NOT gates have high contrast ratio which is more than 35dB between high and low logic states, for a particular wavelength. All these devices are operating with multiple wavelengths. The impact of structural parameter like radius on the operating wavelength and Contrast Ratio (CR) was analyzed. It is found that the optimization of structural parameters makes it possible to obtain the operating wavelength allowed by band structure. These proposed devices were made up of linear waveguides and square ring resonator waveguides, without using nonlinear materials, optical amplifiers and external phase shifters.

Design of all-optical logic gates avoiding external phase shifters in a two-dimensional photonic crystal based on multi-mode interference for BPSK signals

In this paper several new structures of all-optical logic gate in a two-dimensional photonic crystal (PC) based on multi-mode interference (MMI) are proposed and designed. 3π/2 phase shift is introduced between two input ports in the photonic crystal devices through different lengths of the waveguide of two input ports, which makes the logic gates to be directly used for logic operations of binary-phase-shift-keyed (BPSK) signals. XOR, XNOR, OR and NAND logic gates are realized. In order to simulate the performance of the proposed logic gates, the plane wave expansion method (PWEM) and finite difference time domain (FDTD) method are employed. Numerical results reveal that the contrast ratio between Logic 1 and Logic 0 logic-levels is more than 21dB for XOR, 17dB for XNOR, and 13dB for OR and NAND logic operations in the whole C-Band (1530–1565nm). This kind of structure does not adopt nonlinear optical properties, and hence, the power consumption of the device is very low and the size of the device is very small. Therefore, the proposed logic gate has the potential to constitute photonic integrated components that will be used in all-optical signal processing, photonic computing and all-optical networks.

Superconductor/ferromagnet current source

We demonstrate that a multiply connected superconducting structure in combination with a perpendicularly magnetized magnetic dot can be used as a current source for superconducting elements and as an external phase shifter. The concept has been tested by measuring the superconducting Tc(B) phase boundary and critical current of an Al superconducting loop placed on the top of a micron-sized Co∕Pd magnetic dot. A pronounced asymmetry in the voltage–current characteristic of the loop with respect to the polarity of the external magnetic field, as well as a shift of the Tc(B) phase boundary along the field axis indicate the presence of a persistent current in the loop.

Characteristics of Surface Acoustic Wave Coupler Using Quadrature Unidirectional Transducer Structure

A new type of surface acoustic wave (SAW) coupler has been proposed, which is composed of a cascaded group type unidirectional interdigital transducer (UDT) structure to achieve desired performances without gratings and external phase shifters. In order to confirm the performances, simulations and experiments are applied. Predictions are also verified by simulations and experiments. A linear circuit composition procedure for multiport elements is applied in order to explain the meander resistive effect. Cascade-connected ports are prepared for the meander electrode. An improved cascaded UDT structure has been proposed to achieve wideband performances. A filter with a bandwidth twice as that of the conventional one is obtained. Furthermore the structure is applied to a Ring-type filter. High sidelobe rejection and low loss performances, and the miniature chip size of the filer are observed.

Single‐phase unidirectional magnetostatic forward volume wave transducer using internal metal reflective arrays

AbstractThis paper describes the experimental results of a single‐phase unidirectional magnetostatic forward volume wave transducer (MSFVW); this transducer effectively utilizes the reflections of metal strips placed asymmetrically in it. To design a single‐phase unidirectional transducer having internal reflectors, it is necessary to know the reflection characteristics of the metal strips but no study has been performed as yet to find the magnitude and phase of the reflection coefficient. Here, the reflection characteristics of a metal strip array for MSFVW are studied experimentally. For the single strip electrode, the reflection coefficient is in the range of 0.3 – 0.4, which is about one order higher than the value for surface acoustic wave (SAW) devices. Then it is shown for the first time that by properly utilizing the metal strip reflections, a unidirectional transducer can be realized without attaching an external phase shifter. The directivity of 13 dB was obtained for a transducer using four reflecting strips (which is a large value of directivity by a comparatively small number of elements). The phase of strip electrodes as determined from the direction was −90 deg, which is 180 deg different from the SAW devices.

Frequency Variable Oscillator Using a Monolithic SAW Phase Shifter

A new frequency variable oscillator with a monolithic SAW phase shifter is reported. A 214 MHz monolithic SAW phase shifter is fabricated on a silicon substrate with ZnO film. A voltage controlled phase shift is measured and discussed. An SAW oscillator is implemented with this phase shifter and its frequency is controlled by external voltage. A frequency shift of 120 kHz (a relative variation of 560 ppm) and excellent modulation characteristics are obtained without an external phase shifter.