Showing papers on "Return loss published in 1994"
TL;DR: In this paper, an all-fiber narrowband transmission filter (FWHM=0.25 nm) that is compact and exhibits high return loss (30 dB or better) is demonstrated using simultaneously written matched-pair, side-by-side Bragg gratings in a Michelson interferometer configuration.
Abstract: An all-fiber narrowband transmission filter (FWHM=0.25 nm) that is compact and exhibits high return loss (30 dB or better) is demonstrated using simultaneously written matched-pair, side-by-side Bragg gratings in a Michelson interferometer configuration. >
97 citations
TL;DR: In this article, a theoretical study of microstrip crossovers is presented, where the insertion of discrete shunt capacitors is investigated and treated as linear lumped elements and connected by via-holes of rectangular cross section.
Abstract: A theoretical study of microstrip crossovers is presented. For an air-bridge interconnect in a crossover configuration, the equivalent circuit examined exhibits low-pass filter characteristics. To reduce the return loss in the passband, insertion of discrete shunt capacitors is proposed and investigated. These shunt capacitors are treated as linear lumped elements and connected by via-holes of rectangular cross section. It is emphasized that air-bridges, via-holes and lumped elements used in this particular application are all rigorously included in a full-wave spectral-domain analysis. >
76 citations
TL;DR: In this paper, the characteristics of center probe-fed cylindrical dielectric ring resonator antennas with an air gap were studied both theoretically and experimentally, and the return loss of the TM01δ mode was evaluated by using the finite-difference time-domain (FDTD) method and the result agrees well with the measured data.
Abstract: The characteristics of centre probe-fed cylindrical dielectric ring resonator antennas with an air gap are studied both theoretically and experimentally. The return loss of the TM01δ mode is evaluated by using the finite-difference time-domain (FDTD) method and the result agrees well with the measured data. It is demonstrated that the impedance bandwidth can be improved by adjusting the air-gap spacing.
57 citations
TL;DR: In this paper, a complete linear automatic-gain control (AGC) amplifier for a 10 Gb/s optical fiber link was integrated on a single chip, using a Si-bipolar production technology with f/sub T/spl ap/22 GHz.
Abstract: A complete linear automatic-gain-control (AGC) amplifier for a 10 Gb/s optical-fiber link was integrated on a single chip, using a Si-bipolar production technology with f/sub T//spl ap/22 GHz. It is characterized by a high gain of 37 dB, linear operation over a wide input dynamic range of 47 dB, a maximum data rate of 13 Gb/s, and a gain-independent 3-dB cut off frequency of 10 GHz. The circuit consumes 850 mW at a single supply voltage of -6.5 V. It can be operated in both a single-ended and differential mode. A novel 50-/spl Omega/ input matching circuit with only small return loss is used. Two separate output buffers with a constant output voltage swing of 500 mV/sub p-p/ allow splitting up the output signal without use of external components. >
54 citations
Patent•
19 May 1994
TL;DR: In this article, a transmission line driver circuit for data communication transmitters that is capable of meeting the return loss specifications as well as the electrical interface specifications as defined by C.I.T. standards for E1/T1 transmission is presented.
Abstract: A transmission line driver circuit for use in data communication transmitters that is capable of meeting the return loss specifications as well as the electrical interface specifications as defined by C.C.I.T.T. standards for E1/T1 transmission. The line driver circuit of the present invention maintains minimum output impedance during the entire dynamic range of the transmit signal while meeting the pulse shape template requirements. The circuit includes a predriver stage that controls the slew rate of the transmit signal within the constraints of the pulse template. This allows a subsequent output driver stage to enjoy fast slew rates, large gain and dynamic range, and very small output impedance to meet the return loss specification.
25 citations
01 Sep 1994
TL;DR: In this article, the first active coplanar circulators for the 40 GHz band were designed and fabricated using the CPW model library in the CAD package LIBRA, and they were used for InP and GaAs for frequencies up to 80 GHz.
Abstract: For the first time, several active coplanar circulators have been designed and fabricated for the 40 GHz band. The technology for these circuits is the PM-HFET technology from Daimler Benz in Ulm. The introduced designs utilize the new CPW model library in the CAD package LIBRA. The return loss of the electronic circulator is better than ?15 dB and the insertion loss is typically ?3 dB for a bandwidth of about 6 GHz at a center frequency of 40 GHz. The isolation between the ports is better than ?20 dB in the frequency band. New designs on InP and GaAs have been made for frequencies up to 80 GHz.
17 citations
20 Jun 1994
TL;DR: In this article, a rigorous calculation of the magnetic current distribution and the radiated field for slot antennas in uniplanar technology is presented, based on use of the integral equations technique associated with a 2D method of moments.
Abstract: A rigorous calculation of the magnetic current distribution and the radiated field for slot antennas in uniplanar technology is presented. The analysis is based on use of the integral equations technique associated with a 2D method of moments. The calculated results are compared to the experimental ones. A precision of 1% for the return loss and a good agreement for radiation patterns are obtained.
14 citations
Patent•
03 Jun 1994TL;DR: In this article, an iterative ladder network constructed according to a point discontinuity model for individual components of the system in which input and output reflection coefficients and an attenuation coefficient are calculated for each component based on measured or specified insertion loss and VSWR or return loss values, and the ladder is analyzed by processing the coefficients forward in the direction of power flow.
Abstract: A method of facilitating construction of a microwave system which permits the evaluation of a variety of hardware construction options and subsequent evaluation of their effectiveness by measuring or otherwise determining appropriate physical parameters of selected components arranged in a selected order to predict the power response uses an iterative ladder network constructed according to a point discontinuity model for individual components of the system in which input and output reflection coefficients and an attenuation coefficient are calculated for each component based on measured or specified insertion loss and VSWR or return loss values, and the ladder is analyzed by processing the coefficients forward in the direction of power flow.
12 citations
TL;DR: In this paper, a novel ferrite grid electromagnetic wave absorber composed of sintered ferrite is proposed, which is based on the condition that the return loss should be above 20 dB at 30 MHz, its wideband characteristics for suppressing reflections compared to a single-layer absorber are demonstrated by computer simulation.
Abstract: A novel ferrite grid electromagnetic wave absorber composed of sintered ferrite is proposed. Based on the condition that the return loss should be above 20 dB at 30 MHz, its wideband characteristics for suppressing reflections compared to a single-layer absorber are demonstrated by computer simulation.
Calculating the return loss by varying the geometrical parameters of the ferrite grid, an optimum structure is determined which gives the maximum frequency band. In addition, it is found that the return loss of the grid absorber is impaired by an air gap between the ferrite and conductor. Moreover, the operating characteristics of the grid absorber are demonstrated by experimental models.
9 citations
TL;DR: In this article, the authors presented a technique based on the full-wave, two-dimensional spectral domain method and the distributed transmission line approach to analyze structures with a combination of conductor width and dielectric height variations.
Abstract: This paper presents a technique based on the full-wave, two-dimensional spectral domain method and the distributed transmission line approach to analyze structures with a combination of conductor width and dielectric height variations. The technique is applied to a regular taper and the results are compared with existing models. A matched taper transition is then designed based on simultaneous variation of the conductor width and dielectric height such that their ratio is kept constant. The analysis of such tapers is carried out and compared to measured data. It is shown that significant reduction in the return loss can be achieved with such transitions over fairly wide, tunable frequency ranges. >
8 citations
TL;DR: In this paper, an analytical expression for determining load-reflection coefficient phase-angle values that will lead to maximum and minimum return losses from a terminated two-port network is derived in terms of S-parameters and a load whose reflection-coefficient magnitude can be any value greater than zero and less than or equal to unity.
Abstract: An analytical expression is derived for determining load-reflection coefficient phase-angle values that will lead to maximum and minimum return losses from a terminated two-port network. The expression is derived in terms of two-port network S-parameters and a load whose reflection-coefficient magnitude is a constant but can be any value greater than zero and less than or equal to unity. The equation is useful for cases where it is desirable to know how to position a load (1) to obtain maximum return loss for network-matching purposes or (2) to obtain minimum return loss for some types of reflector antenna applications. Two examples are given: One shows that for some types of reflector antennas with a mesh-type surface that is backed by another reflecting surface, a resonance phenomenon can occur and cause unexpectedly large dissipative losses (>30 dB) to occur. The other example shows that when a particular type of reflector antenna with a dielectric layer becomes wet from rain or condensation, large (>10 dB) signal losses can occur. For both examples, equations presented in this article were used to calculate the exact load-reflection coefficient phase values that led to worst-case return loss values. In practical situations, once the phenomenon is understood and predictable, steps can be taken to avoid these resonance regions. >
22 May 1994
TL;DR: In this paper, a two stages four sections GaAs monolithic matrix distributed amplifier covering the frequency range from 2 to 52 GHz was designed and the achieved gain is about 9 dB and the return loss is better than 12 dB.
Abstract: This paper discusses design, performance and fabrication of a two stages four sections GaAs monolithic matrix distributed amplifier covering the frequency range from 2 to 52 GHz. The achieved gain is about 9 dB and the return loss is better than 12 dB. The devices we used are 2/spl times/25 /spl mu/m, 0.2 /spl mu/m recessed gate AlGaAs HEMTs and the coplanar waveguide was the propagation medium for this broadband amplifier. The chip dimensions of the amplifier including the bias networks are 2.0 mm/spl times/2.5 mm. >
16 Oct 1994
TL;DR: In this article, a 1.5 V operating GaAs 2/spl sim/9 GHz ultrawide-band MMIC amplifier for portable wireless LAN, microwave link and satellite communication applications has been developed.
Abstract: A 1.5 V operating GaAs 2/spl sim/9 GHz ultrawide-band MMIC amplifier for portable wireless LAN, microwave link and satellite communication applications has been developed. This amplifier has 16/spl plusmn/1 dB gain and more than 10 dB input and output return loss in the 2/spl sim/9 GHz frequency range with 118 mA operating current. Measured 1-dB compression power is 13 dBm at 0 dBm input power and minimum noise figure is 4.8 dB. When operated at 3 V and 128 mA, this amplifier has up to 18/spl plusmn/1 dB gain, 18 dBm 1-dB compression power, more than 10 dB return loss and 4.9 dB minimum noise figure.
25 Jul 1994
TL;DR: In this paper, the authors compared the performance of the fiber-to-waveguide (F2W) connection in terms of insertion loss, time requirement, return loss and environmental performance.
Abstract: The technique of the fibre to waveguide connection are described and compared in terms of insertion loss, time requirement, return loss and environmental performance. The most promising techniques are outlined together with the latest technical improvements.
20 Jun 1994
TL;DR: In this paper, an inserted coplanar feed line for matching the MCP antenna to 50/spl Omega/ impedance is developed based on the resolution of the electric field integral equations (EFIE) by the method of moments (MoM) where triangular subdomain discretization is used to handle the arbitrary shape of the radiating elements.
Abstract: Planar antennas are widely used as radiating elements in large arrays. The commonly used microstrip shapes are rectangular and circular patches. The microstrip circular patch (MCP) requires less area compared to the rectangular one. However, the edge-fed circular patch antenna presents a high return loss which restricts the use of a 50/spl Omega/ microstrip transmission line as a feed. In the present work, an inserted coplanar feed line for matching the MCP antenna to 50/spl Omega/ impedance is developed. The analysis is based on the resolution of the electric field integral equations (EFIE) by the method of moments (MoM) where triangular subdomain discretization is used to handle the arbitrary shape of the radiating elements. Two new MCP antennas which improve the matching performances at the resonance frequencies of the TM/sub 11/ and TM/sub 12/ modes are discussed. >
Journal Article•
TL;DR: Using a calcite crystal as a directional coupler in return-loss meters effectively separates out return loss contributions arising from connections and the target fiber as discussed by the authors, which can be used in return loss meters.
Abstract: Using a calcite crystal as a directional coupler in return-loss meters effectively separates out return-loss contributions arising from connections and the target fiber.
TL;DR: In this paper, a tapered ferrite rod antenna at 20 GHz was used to achieve phase shifts of greater than 100°/λ 0 with a better than 10 dB return loss over the complete bias range.
Abstract: Experimental investigations were performed on a tapered ferrite rod antenna at 20 GHz. By inserting a section of the rod into a solenoid, phase control was achieved by varying the applied DC solenoid current. Phase shifts of greater than 100°/λ0 were attained. The gain and radiation patterns did not change significantly with the applied bias. The return loss was somewhat more sensitive, but a better than 10 dB return loss was obtained over the complete bias range.
Patent•
22 Aug 1994TL;DR: In this paper, a return-loss detector for a serial digital signal source uses a return loss bridge circuit to exploit the broadband spectral characteristics of a signal source to monitor the termination conditions of a system being driven.
Abstract: A return-loss detector for a serial digital signal source uses a return-loss bridge circuit to exploit the broadband spectral characteristics of a serial digital signal from the signal source to monitor the termination conditions of a system being driven. A differential pair of serial digital signals from the source are input to the bridge circuit having a reference termination in one leg and the system termination in the other. A broadband detector is used at the output of the bridge circuit to generate an error signal, which is measured by a detector or metering circuit. The measured signal may be displayed as a value in dB or may be input to a comparator to provide an alarm or warning signal to an operator.
20 Jun 1994
TL;DR: In this article, two configurations to match the coupled slots antenna to the coplanar waveguide are proposed, based on the use of integral equations technique solved by a 2-D method of moment.
Abstract: Several coupled slots antennas fed by a coplanar waveguide in uniplanar technology have been investigated using a full wave analysis. It is based on the use of integral equations technique solved by a 2-D method of moment. Theoretical results are compared to measured ones, and a good agreement is obtained for either return loss and the radiation patterns. Two configurations to match the coupled slots antenna to the coplanar waveguide are proposed.
23 May 1994
TL;DR: In this article, the authors presented a broadband quadrature coupler implemented with a unique braided microstrip structure, which is completely compatible with MMIC processing, employing only the processing steps required to fabricate MIM capacitors.
Abstract: This paper presents a broadband quadrature coupler implemented with a unique braided microstrip structure. This novel structure consists of 64 air bridge crossovers and is completely compatible with MMIC processing, employing only the processing steps required to fabricate MIM capacitors. The airbridge crossovers create extremely tight coupling coefficients which are independent of the substrate thickness and, therefore, can be used on the thin substrates employed for MMICs. This paper contains the test results of a 2.5 to 8 GHz coupler fabricated on a 125 /spl mu/m GaAs substrate. The coupler achieved less than /spl plusmn/25 dB of amplitude imbalance with better than 17 dB return loss and 11 dB of isolation over the almost 2 octave bandwidth. This bandwidth and performance are the best reported for braided structures on thin GaAs substrates. >
Patent•
19 Aug 1994
TL;DR: In this paper, the authors proposed a small-sized optical fiber line switching device where an excess connecting point with an optical fiber is removed, whose mechanism is simple, and where insertion loss and return loss are small.
Abstract: PURPOSE:To obtain a small-sized optical fiber line switching device of 2:2 where an excess connecting point with an optical fiber is removed, whose mechanism is simple, and where insertion loss and return loss are small. CONSTITUTION:This device is provided with a 1st optical fiber line constituted of a pair of optical fibers 1 and 2 whose tip parts pierce inner rings 41a and 42a rotatably attached to bearings 41 and 42 and which are fixed in parallel with the inner rings, and a 2nd optical fiber line constituted in the same manner; and provided with an aligning member 30 in which the tip parts of the 1st and the 2nd optical fiber lines are respectively inserted from both sides so that they may be positioned to be opposed to each other, and rotating mechanisms 20 to 22 rotating the inner ring 41a fixing the 1st optical fiber line and the inner ring 42a fixing the 2nd optical fiber line by 90 deg. in a reverse direction to each other, then the connection of the 1st and the 2nd optical fiber lines is switched.
27 May 1994
TL;DR: In this paper, a monolithic six-port module MSPM with resistive bridges is presented, which can act as directional resistive couplers and is shown how these simple structures may act as a directional coupler.
Abstract: This paper presents the design of monolithic six-port module MSPM with resistive bridges. It shows how these simple structures may act as directional resistive couplers. Final MMIC circuit includes six-port junction and matched MESFET detectors covering an area of 1.2 mm2 in the frequency range 100 MHz to 3 GHz. The MSPM was bonded in a MIC structure with output coaxial connectors. Experimental results obtained using a commercial network analyzer and our measurement system are in good agreement. The magnitude and the phase variation between the two measurement systems are equal to .2dB and 2 degrees for respective modulus values of 0, 6, 12 dB. For a nominal 20 dB return loss load, the differences are respectively equal to 0.5dB and 5 degrees in the operational frequency band. In a second step, the measurement system was integrated inside the tips of a probe station and experimental results will be available at the ARFTG session.
23 May 1994
TL;DR: A planar 3 dB coupler in the form of an 8-port elliptical disc is investigated theoretically and experimentally in this paper, where the hybrid consists of additional reactive stubs and impedance steps for tuning purposes.
Abstract: A planar 3 dB coupler in the form of an 8-port elliptical disc is investigated theoretically and experimentally. The hybrid consists of additional reactive stubs and impedance steps for tuning purposes. The new device features flat coupling, good return loss and isolation over a 20% relative bandwidth. >
23 May 1994
TL;DR: In this paper, the authors presented a miniature fixture, in which a semiconductor chip can be assembled, attached to the end of a long 19 mm diameter metal pipe, which is part of the refrigeration system.
Abstract: Research of sub micrometer structures in semiconductor physics often requires measurement of extremely weak signals at millimeter wave frequencies generated by small semiconductor chips at temperatures close to the absolute zero. In this paper we present a miniature fixture, in which such a semiconductor chip can be assembled. The fixture is attached to the end of a long 19 mm diameter metal pipe, which is part of the refrigeration system. These mechanical and environmental constraints dictate special design to achieve good performance up to 40 GHz. The complete fixture with a 50 ohm microstrip line exhibits a loss of 0.5 db at 20 GHz and 1.3 db at 40 GHz. The return loss is better than 15 db at 20 GHz and better than 10 db at 40 GHz, which is more than adequate for the required measurements. >
20 Jun 1994
TL;DR: In this article, the authors demonstrate that the bandwidth of a center probe-fed cylindrical dielectric ring resonator antenna can be increased by stacking another DR of the same dimensions on the top of the fed DR.
Abstract: Dielectric resonators (DR) find application in the design of microwave antennas. The radiation patterns of DR antennas are related to their excited resonant model(s). Dielectric resonators of low dielectric constant are usually employed to give a reasonable impedance bandwidth. We demonstrate that the bandwidth of a center probe-fed cylindrical dielectric ring resonator antenna can be increased by stacking another DR of the same dimensions on the top of the fed DR. The return loss and the radiation patterns of the stacked DR antenna are computed using the finite difference time-domain (FD-TD) method. The numerical results so obtained are compared to experimental measurements. >
TL;DR: In this article, the authors presented a broadband quadrature coupler realized using a novel braided microstrip structure that consists of 64 air-bridge crossovers, which achieved better than 17dB return loss, 11 dB of isolation and ± 0.75 of amplitude variation over the almost 2-octave bandwidth.
Abstract: This article presents a broadband quadrature coupler realized using a novel braided microstrip structure that consists of 64 air-bridge crossovers. The test results of the 2.5–8-GHz single-section coupler fabricated on a 125-μm-thick GaAs substrate are presented. This coupler achieved better than 17-dB return loss, 11 dB of isolation and ±0.75 of amplitude variation over the almost 2-octave bandwidth. This bandwidth and performance are the best reported for a braided microstrip coupler. © 1994 John Wiley & Sons, Inc.
22 May 1994
TL;DR: In this article, a complete linear automatic-gain control (AGC) amplifier for a 10 Gb/s optical fiber link was integrated on a single chip using a Si-bipolar production technology.
Abstract: A complete linear automatic-gain-control (AGC) amplifier for a 10 Gb/s optical fiber link was integrated on a single chip using a Si-bipolar production technology. It is characterized by a high gain of 37 dB, linear operation over a wide input dynamic range of 46 dB, a maximum data rate of 13 Gb/s, and a gain-independent 3-dB cut-off frequency of 10 GHz. Moreover, a special 50-/spl Omega/ input termination circuit with only small return loss as well as two separate output buffers are used. >
Patent•
22 Dec 1994
TL;DR: In this article, the authors proposed a light receiving device with a high return loss characteristic capable of unnecessitating the adjustment of an optical axis, reducing man-hour and dealing with automation in assembly.
Abstract: PURPOSE:To provide a semiconductor light receiving device with a high return loss characteristic capable of unnecessitating the adjustment of an optical axis, reducing man-hour and dealing with automation in assembly. CONSTITUTION:This device is provided with a semiconductor photodetector 1, an optical fiber 3, a concave mirror 2 optically connecting the semiconductor photodetector 1 with the optical fiber 3, and the outgoing end of the optical fiber 3 is placed on a position shifting from the central axis of the concave mirror 2, and the semiconductor photodetector 1 is arranged on the position where a light beam radiating from the outgoing end of the optical fiber 3 is reflected and converged/image formed, and the direction of the light receiving surface is decided so that an incident beam on the light receiving surface of the semiconductor photodetector 1 is reflected outside the concave mirror 2, and the high return loss characteristic is provided by suppressing a beam returning to the optical fiber 3.
20 Jun 1994
TL;DR: In this paper, planar fed printed dipoles have been demonstrated and two planar feeders have been implemented in MMIC and MIC circuits and allow for easy insertion of printed antennas for a multitude of applications.
Abstract: Two novel planar fed printed dipoles have been demonstrated. One utilizes a CPW to slotline transition and the other an original microstrip to slotline transition. In both cases, proper selection of dielectric constant and thickness for the substrate relative to the wavelength is required to ensure proper antenna performance. The radiation patterns and return loss measurements for these antennas revealed that excellent performance can be achieved by both feeding methods. These designs are straightforward to implement in MMIC and MIC circuits and allow for easy insertion of printed antennas for a multitude of applications. >