Ring Coupler Research Articles

Miniaturized and Large-Division-Ratio Ring Coupler Using Novel Transmission-Line Elements

In this letter, a novel transmission-line element that is able to exhibit a high-impedance passband is proposed and applied for coupler realization with a large power division ratio. The analysis of the transmission-line element was conducted by its equivalent circuit model and the closed-form equations for the pole and zero frequencies of the effective impedance were derived to help control the passband impedance and phase responses by the lumped parameters. The high-impedance feature of the presented artificial line was exploited to experimentally develop a 12 dB ring coupler, which occupies only 29% footprint of the conventional coupler at 3.5 GHz. Experimental results are in good agreement with the simulation data.

Empirical Formulas For Designing Gap‐Waveguide Hybrid Ring Coupler

ABSTRACTA new type of hybrid ring coupler (or rat‐race coupler)—the gap‐waveguide ring hybrid has been developed in this work. The advantages of the new gap‐waveguide ring hybrid are low manufacturing cost since the good electrical contact between metal plates is not required, and lower transmission loss compared to microstrip line since there is no dielectric material needed. Therefore, the gap‐waveguide technology opens up a possibility of waveguide integration circuit from millimeter wave up to terahertz. We present an empirical formula for designing the gap‐waveguide ring hybrid based on simulated data and has been verified by measurements of a prototype of the ring hybrid realized at 16 GHz. The prototype has an operating frequency band of 2 GHz around 16 GHz, with a reflection coefficient below −10 dB and a phase difference between two output ports of 182° ± 2°. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:1917–1920, 2013

A universal ring 0°/180° coupler for arbitrary power division

A universal ring structure is presented for the 0°/180° coupler operation with arbitrary power division ratios. The ring circuit topology is investigated for the 0°/180° coupler operation based on the 4-port admittance parameter analysis. The universal design equations are derived in terms of 4-port admittance parameters of the coupler and the 2-port branch parameters of the ring. The universal conditions for the coupler operation are presented in terms of the self and the mutual admittances of the ring. The universal ring topology under consideration is quite general with minimized circuit restrictions and the presented results are applicable to almost all types of ring coupler structures including the lumped as well as the distributed circuit implementations. As an example, the presented results for the universal ring are applied successfully to the design of uniform transmission line ring couplers with arbitrary values for the line impedances, electrical lengths, and the power division ratios. © 2012 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:543–547, 2013; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.27351

DESIGN METHOD OF MINIATURIZED RING COUPLER USING PHASE SHIFTERS CONSISTING OF FULLY-DISTRIBUTED COMPOSITE RIGHT/LEFT-HANDED STRUCTURES

A new method to design a miniaturized ring coupler consisting of multiple open stubs on the inside of the ring is proposed. It is shown that this coupler topology may be seen as fully-distributed composite right/left handed (CRLH) small-size phase shifters, cascaded in a ring conflguration. The CRLH phase shifter is analyzed in detail and a design method is proposed, pointing out the condition to obtain a reduction of its length. Using the fully- distributed CRLH based phase shifter, a ring coupler is conflgured and analyzed in comparison with the traditional ring coupler, showing that both couplers have similar characteristics. To validate the proposed design method, a 3-dB CRLH based ring coupler is designed and fabricated. The experimental results show a very good agreement with the predicted results obtained by electromagnetic simulation. The printed area of the fabricated coupler is 49% smaller compared to the traditional ring coupler.

Electromagnetic Devices Applications of EBG for Systems Communications

This paper presents the study and applications of EBG (Electromagnetic Band Gap)/PBG (Photonic Band Gap) substrates, of planar microstrip structures, including quadrature directional couplers, rat-race (ring coupler) and impedance transformers. Through specific programs developed in FORTRAN PowerStation, the frequencies and couplings for each structure are obtained. Also are used the PACMO—Computer Aided Design in Microwave program developed by H.C.C. Fernandes. Results of the dimensions and coupling of these devices, varying the frequency band (cellular communication and Wimax systems) and permittivity of the substrate, are obtained, comparing the results of conventional materials with EBG/PBG materials in the s and p polarizations.

Small-size ring coupler design method based on fully distributed composite right/left-handed approach

A new method to design a small-size ring coupler is proposed, showing that the coupler may be seen as consisting of fully distributed composite right/left-handed phase shifters. A 3 dB ring coupler is designed by using the proposed method. The coupler is analysed numerically and then experimentally characterised. It is shown that the experimental results are in very good agreement with the expected ones. For the designed and fabricated coupler, the area reduction is about 50%, compared to the conventional ring coupler.

Wide aperture circularly polarized antenna for small telemetry satellites

This paper focuses on the design of a telemetry antenna system intended for small satellites. It provides an axial ratio (AR) lower than 3 dB over ±60° conical space angle with over 20% of bandwidth. The antenna consists of a multilayer patch element fed by a wideband feeding circuit. The latter is an appropriate adjustment of 90° hybrid couplers and 180° ring coupler. We show that this design provides high-quality circular polarization properties for agile small satellites without having to suspend their mission to download their data and also without sacrificing the antenna low profile and wide bandwidth. The antenna is fabricated and the experimental performance is presented and followed by a discussion.

A wide tunable fiber laser for two independent C-band and l-band wavelengths

A double-ring laser with a single 1480nm pump was proposed and demonstrated using the combination of a ring coupler and a C/L-band coupler. One ring for an L-band wavelength was pumped by a lasing light which was transferred from the other ring for a C-band wavelength. The laser had a total bandwidth of 70nm, with 35nm continuously tunable at each wavelength band within a 1dB power deviation. High lasing powers of more than 0dBm were maintained as the pump power decreased to 60mW. This laser also supported two independent tunable lasing wavelengths at the same time. The 1557nm pumped L-band lasing had 25% improvement in power conversion efficiency and 60% reduction in threshold pump power compared with directly 1480-nm-pumped L-band lasing. This wide bandwidth and highly power-equalized laser was achieved with high output lasing power and low power consumption.

Miniaturized Ring Coupler with Arbitrary Power Divisions Based on the Composite Right/Left-Handed Transmission Lines

A novel and miniaturized ring coupler capable of presenting arbitrary power divisions is proposed using the composite right/left-handed (CRLH) transmission lines. The unbalanced CRLH transmission lines that can be easily tailored to implement transmission lines of high or low Bloch impedance are applied to enhance the coupler's capability of arbitrary power divisions. To support our idea, a ring coupler that offers a 6 dB power division ratio and occupies only 44% of the conventional footprint was experimentally realized. Experimental results agree well with the simulation data. The proposed CRLH configuration demonstrates an alternative for implementing a compact ring coupler with arbitrary power division ratios.

Ridge Substrate Integrated Waveguide (RSIW) Dual-Band Hybrid Ring Coupler

A novel dual-band ring coupler is proposed in Ridge Substrate Integrated Waveguide (RSIW) technology. The structure is based on two concentric rings with the outer ring loaded by a low insertion loss de-multiplexing scheme allowing independent dual band operation. The RSIW ensures a wide-band fundamental mode operation covering both frequency bands while providing a compact design. A C/K band coupler is experimentally verified showing coupling bandwidths of 6.9% and 14.6% centered at 7.25 and 20.5 GHz, respectively.

CONTOUR- AND GRID-BASED ALGORITHM FOR MIXED TRIANGULAR-RECTANGULAR PLANAR MESH GENERATION

A mesh generation algorithm for the Method of Moments (MoM) is described. The algorithm, named CGSM, can mesh arbitrary planar shapes described with line segments and circular arcs into mixed triangular and rectangular cells. CGSM creates contours of the meshed shape and uses them to provide edge mesh (denser mesh near edges), creates an adaptive grid and uses it to insert axis-aligned rectangles in the interior, and flnally, triangulates the remaining area (the Delaunay condition is imposed on the triangulation). CGSM is compared to two commercial applications (Designer r and IE3D TM ) on the example of a 2-GHz hybrid ring coupler. The same simulation results are obtained. However, with CGSM, simulation time is signiflcantly reduced.

Miniaturized Hybrid Ring Coupler Using Electromagnetic Bandgap Loaded Ridge Substrate Integrated Waveguide

A novel compact Ridge Substrate Integrated Waveguide (RSIW)-based hybrid ring coupler is hereby presented. The size miniaturization is accomplished through a twofold approach. First, the RSIW is used to reduce the coupler waveguide transverse dimension. The RSIW of the hybrid ring is then loaded by Electromagnetic Bandgap (EBG) structures, etched in its non-ridged broadwall, exploiting their slow wave effect to reduce the longitudinal dimension. It is demonstrated that the use of EBG-loaded RSIW can lead to a size reduction of more than 48% and 91% with respect to the unloaded RSIW and conventional SIW hybrid ring couplers, respectively.

Design of Ring Couplers for Arbitrary Power Division With 50 $\Omega$ Lines

A new 0°/180° ring coupler structure is proposed for the arbitrary power division ratios. The proposed coupler consists only of 50 Ω transmission lines with the simple ring structure. The electrical lengths of the 50 Ω branches are adjusted to obtaining any desired values of the power division ratio without changing the impedance. A very wide range of power division ratios can be obtained easily with the simple 50 Ω line based ring structure.

Compact and broadband tunable hybrid ring coupler using synthetic left- and right-handed transmission lines

In this letter, we present a frequency tunable hybrid ring coupler based on the concepts of a synthetic left- and right-handed transmission line.The proposed ring coupler makes use of lumped inductor-capacitor (LC) elements to greatly reduce the circuit size; meanwhile, the frequency responses of the coupler can be tuned by direct current (DC) bias voltages. The fabricated hybrid ring coupler shows a wideband performance with an insertion loss of less than 2.5 dB from 1.7 to 3.3 GHz. For this frequency band, the isolation is maintained at more than 24 dB. When the circuit is excited to get a pair of differential signal, less than ±5° phase error is observed for the whole frequency range. This hybrid has a 78% size reduction compared to the conventional ones and achieved a 64% of fractional bandwidth at 2.5 GHz. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:1379–1382, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25959

A Compact Wideband Ring Coupler Utilizing a Pair of Transitions for Phase Inversion

A new wideband ring coupler utilizing a pair of ultra-wideband planar transitions is introduced in this letter. The two types of transitions (in-phase and inverted phase transitions) are coplanar waveguide-to-parallel stripline transitions, and very similarly structured except for the phase inversion part. The area of the proposed ring coupler is only 41.4% of the conventional ring coupler. The measured bandwidth of the implemented ring coupler with more than 10 dB return loss is 92.5% with the Σ port excitation, and 81.3% with the Δ port excitation. Also, due to good matched properties of the transitions, the ring coupler shows less than ± 0.7 dB amplitude mismatch, less than 4 <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">°</sup> phase difference, and more than 30 dB isolation over the operating frequencies.

Interdigital Ring Coupler Sensor for Parameter Estimation of Moving Objects

Generally, a laser Doppler velocimetry can estimate particle velocity by forming a standing wave region with crossed beams and by counting the brinks of particle scattering. If we apply this concept to microwave measurement in near field, an arrayable measurement of object parameters will be expected with low cost. This paper presents a novel velocity and volume estimation method of small object based on reflection coefficient measurement using near field sensor with an interdigital ring coupler structure. The sensor is designed with electrostatic analysis and FDTD analysis. Experiments are carried out with a constructed sensor. Experiments and simulation results agree well. It implies that this sensor has possibility to measure not only the velocity but also the volume of the target.

A superconducting 180° hybrid ring coupler for circuit quantum electrodynamics

Superconducting circuit quantum electrodynamics experiments with propagating microwaves require devices acting as beam splitters. Using niobium thin films on silicon and sapphire substrates, we fabricated superconducting 180° microstrip hybrid ring couplers, acting as beam splitters with center frequencies of about 6 GHz. For the magnitude of the coupling and isolation, we find −3.5±0.5 dB and at least −15 dB, respectively, in a bandwidth of 2 GHz. We also investigate the effect of reflections at the superconductor-normal conductor contact by means of low temperature laser scanning microscopy. Our measurements show that our hybrid rings are well suited for on-chip applications in circuit quantum electrodynamics experiments.

Metamaterial inspired enhanced far‐field transmission through a subwavelength nano‐hole

AbstractIn the present study, we first demonstrate the polarization and orientation dependent transmission response of split ring resonators at the infrared and visible band. Then, we numerically demonstrate a configuration for the enhancement of power passing through an electrically small hole. By using deep subwavelength optical split ring resonator antennas and couplers we achieved a 400‐fold enhanced transmission from a subwavelength aperture area of the electrical size λ2/25. The power was transmitted to the far field with 3.9 dBi directivity at 300 THz. (© 2010 WILEY‐VCH Verlag GmbH &amp; Co. KGaA, Weinheim)

The Mathematical Basis of Adjunctive Techniques for Enhancement of Vessel Caliber to Maximize Coupler Ring Size for Microanastomoses

The use of ring-pin devices as a nonsuture alternative for microanastomoses is expedient and highly practical, with excellent patency rates. A frequently encountered problem, though, is a significant discrepancy between the donor and recipient vessel lumen size. Rather than accepting the choice of a smaller ring size corresponding to the caliber of the smaller vessel, it may be preferable to instead increase the latter's circumference for potential eversion on the pins by either beveling or "fish-mouthing" the end of the vessel. Arithmetical calculations suggest that a 25% increase in dimensions can thereby be possible at least for thin-walled venous structures. Not only does the capability for selection of a size larger ring simplify drawing the vessel wall through the ring orifice prior to pin impalement, but the resulting larger anastomotic lumen should theoretically increase the potential flow rate across the microanastomosis.

Novel MEMS Dipole/Monopole Antenna for Wireless Systems Operating at 77 GHz

In this paper, we present a novel MEMS antenna designed for operation at 77GHz. The antenna consists of two right-angle metal arms which are supported by two vertical silicon walls. These walls are fabricated using bulk micromachining through Deep Reactive Ion Etching (DRIE) process. The two right-angle arms are fed via a microstrip ring coupler which has two input ports. A new process ∞ow is introduced in this paper, which allows the realization of the proposed antenna on a single silicon wafer. The antenna is analyzed and optimized thoroughly using Ansoft/HFSS. The results show that based on the selection of port of excitation, the proposed antenna can radiate either dipole or monopole patterns. In the dipole (monopole) mode, the antenna has impedance bandwidth of 4.3% (4.2%), gain of 8.9dBi (5.5dBi), radiation e-ciency of 94% (95%). Micromachining technology is very attractive for integrated antennas as it ofiers e-cient packaging, high radiation e-ciency, wide impedance bandwidth, and less mutual coupling between antenna elements. These advantages are more di-cult to be achieved using the conventional planar technol- ogy especially at high frequencies. Research carried out on MEMS antennas can be classifled into two main categories. The flrst category features a ∞at antenna, such as patch, realized on a thin membrane surrounded by air. The membrane can be fabricated via either bulk (1) or surface (2) micromachining technology. This results in reducing the efiective dielectric constant of the medium around the antenna and consequently increases the bandwidth and radiation e-ciency. The second category features a 3D antenna, such as horn or waveguide, realized by etching grooves in a number of silicon wafers via bulk micromachining (3). The walls of these grooves are covered with metal. Each groove represents part of the desired 3D structure. The wafers are bonded together to form the complete 3D antenna. In this paper, a novel MEMS antenna design is presented. The proposed antenna is 3D in shape and it can be fabricated on a single silicon wafer without any need for wafer bonding or hybrid integration. The proposed antenna is capable of operating as either dipole or monopole based on the selection of the port of excitation. 2. ANTENNA STRUCTURE AND FABRICATION TECHNOLOGY The proposed MEMS antenna is shown in Fig. 1. It has two vertical silicon walls that can be fabricated using bulk micromachining through 0.675mm thick high resistivity silicon wafer with dielectric constant of 11.9 and conductivity of 0.05S/m. The width, length, and depth of each wall are 70m, 953m, and 475m, respectively. The last two dimensions correspond to ‚g=2 and ‚g=4 at the operating frequency of 77GHz. The thickness of the remaining silicon substrate is 200m. Two horizontal metal arms are covering the top surfaces of the walls. Two vertical pillars with square cross section of 55m £ 55m are drilled through the entire wafer. The inner surfaces of these pillars are covered with vertical metal arms, as shown in Fig. 1. It can be seen in this flgure that there are gaps between the vertical and horizontal arms. The top surface of the substrate is covered with slotted ground metal plane, through which the silicon walls are going up. This plane serves as a re∞ector that increases the directivity of the antenna. Moreover, it isolates between the antenna and the bulk silicon substrate, which reduces the surface wave losses and increases the radiation e-ciency. All metallic parts of this structure are made of copper with thickness of 3m. From the bottom side of the substrate, the vertical arms are connected to the two output ports of a ring coupler made of microstrip lines. Two feeding microstrip lines are connected to the input ports of the ring coupler. The width of each line is 200m which corresponds to 50› at 77GHz. The ring is made of a microstrip line whose width and characteristic impedance are 88m