Showing papers on "Insertion loss published in 1981"

Coupled lossy transmission line characterization and simulation

Abstract: It has been shown that the frequency domain solution of the coupled lossy transmission line differential equations has a similar appearance to that of the single line. The frequency-dependent n × n characteristic admittance matrix Y0 and propagation matrix Γ can be obtained from network analyzer insertion loss data treating the coupled transmission lines as a 2n-port network. This paper develops a transient simulation technique for coupled lossy transmission lines based on frequency-dependent Y0 and Γ data. Simulation results agree very well with transient measurements.

Piezoelectric polymer probe for ultrasonic applications

Abstract: Miniature piezoelectric polymer hydrophones for ultrasonic field characterization in the low megahertz region have been developed and tested. The principal advantages of these devices over conventional hydrophones are their uniform frequency response and minimal perturbation of the field. These characteristics are achieved by rendering a small central region of a thin sheet of the polymer polyvinylidene fluoride locally piezoelectric, and then supporting the sheet in the field by holding it taut in a metal hoop having dimensions larger than the field being probed. Both single elements having diameters less than 1 mm and multielement arrays have been formed on the polymer. Methods of construction, signal amplification, and, in one design, rf shielding are discussed, and data are presented on insertion loss, sensitivity, frequency response, and immunity to rf interference.

Distributed coupling on polished single-mode optical fibers.

Abstract: The core of a single-mode fiber can be reached by an optically controlled polishing technique which does not alter the fiber's mechanical strength. A directional coupler using two such fibers was designed showing a power extinction ratio from zero to more than 35 dB over a wide range of structure parameters with easy alignment operations and insertion loss lower than 1 dB.

Optical switch attenuator

Abstract: An optical switch having low insertion loss and low crosstalk is provided by two slabs of birefringent material having a polarization rotator as a control element interposed therebetween. By controlling the polarization rotator electrically, a selectable ratio of transmitted-to-displaced output optical power is realized. The optical switch therefore can function as an attenuator to a light beam traversing through it. In the preferred embodiment calcite crystals are used for the slabs, and a liquid crystal cell for the polarization rotator.

Semileaky thin‐film optical isolator

Abstract: Two interesting effects have been experimentally demonstrated for the first time: (1) simultaneous reciprocal and nonreciprocal mode conversion to achieve an isolation effect and (2) magneto‐optic switching between guided and radiation modes. These effects were observed in connection with the construction of a previously proposed thin‐film optical isolator. The isolator consists of a piece of LiNbO3 placed on top of a thin film of yttrium ion garnet (YIG) with a selenium layer to avoid optical contact problems. The isolator, which is 1 cm long, exhibited 10 dB of isolation at λ = 1.15 μm. The observed isolation was better than theoretical predictions and a mysterious isolation direction dependence on mode order was observed. Although the device had 10 dB of insertion loss and required a magnetic field of 40 Oe, with a slight change in wavelength and film composition, it should be possible to reduce the insertion loss and field required to under 1 dB and 0.1 Oe, respectively. These characteristics combined...

Low-cross-talk 2 x 2 optical switch

Abstract: An electro-optical 2 x 2 switch for fiber-optic applications has been developed. Optical cross talk is reduced significantly by inserting two 2 x 1 switches in each optical path. A compact structure is used to contain the four 2 x 1's that are required. We observed -27-dB cross talk and 2.5-dB insertion loss in both switching states. The device is controlled by a 5-V twisted-nematic liquid-crystal cell. Multimode, unpolarized light is switched.

Photon probe fault locator for single-mode optical fiber using an acoustooptical light deflector

Abstract: A new backscattering technique for diagnosing the attenuation characteristics, spatial imperfections with length (fault location), and splice loss in a single-mode optical fiber has been developed by using a TeO 2 acoustooptical light deflector operating at 120 MHz. Due to the small insertion loss and high extinction ratio of the deflector, the dynamic range of the backscattered signal has been increased by at least 10 dB, which corresponds to the extension of 5 km in measurable length for fiber loss of 1 dB/km, compared with the conventional back-scattering technique in which the beam splitter and polarizer-analyzer combination are utilized. Another advantage of this technique is in that the saturation of the amplifier is avoided by arbitrarily cutting off a large power in the early stage of the Rayleigh scattering signal. A single-mode fiber of 19.2 km in length has been examined, and the distance for fault location up to 18.4 km was obtained.

Resonated GaAs FET devices for microwave switching

Abstract: Several designs of monolithic switches for X-band applications have been fabricated and tested. These switches, which consist of two parallel-resonated GaAs FET's in a series SPDT configuration, have very low dc power dissipation, low insertion loss, and are bidirectional. An insertion loss of 0.7 dB with 28-dB isolation at 10.2 GHz has been measured for these devices. A simple equivalent circuit model is presented which explains reasonably well the basic features of resonated GaAs FET switches. The tradeoffs between performance and bandwidth, and the important design criteria, particularly with respect to the layout of monolithic inductors, are investigated.

Modeling and Characterization of Microstrip-to-Coaxial Transitions

Abstract: A simple circuit model for the transition from a Iossy microstrip to coaxial line has been developed on an experimental basis. The proposed model can be used to predict accurately the insertion loss and insertion phase over a wide frequency range. Since explicit formulas for the model element values are given, these elements, representing the parasitic of the transitions, can be taken into account very easify when the microstrip is used as a test fixture for measuring the parameters of solid-state devices. The practical use of the model has been examined for several Z/sub 0/=50-omega lines on both Epsilam-10 and 99-percent alumina substrates with standard SMA coaxial connectors.

Insertion loss studies on models of automotive exhaust systems

Abstract: Transmission loss, noise reduction, and insertion loss are the three main characteristics used to describe the performance of a muffler in an automotive exhaust system. Of these characteristics, insertion loss is the most useful. Unlike transmission loss and noise reduction, insertion loss is dependent on both source and radiation impedances. In this paper, source and radiation impedances were measured. The insertion loss of exhaust systems was predicted using theoretical values of radiation impedance and measured values of source impedance. Comparisons of predicted and measured insertion loss are given for various source and radiation conditions. So far the investigations are confined to an electroacoustic driver source and an expansion chamber muffler.

Computer-Optimized Design of Quarter-Wave Acoustic Matching and Electrical Matching Networks for Acoustic Transducers

Abstract: An iterative computer program was developed to optimize the parameters for the acoustic matching layer(s) and the electrical matching network of a transducer for a minimum length of the impulse response. By including the interactions between electrical and acoustic matching in the authors' model, the quality of the transducers has been significantly improved. A 3.65 MHz center frequency transducer, made of Murata PZT, was constructed to verify the computer results. The impulse response was approximately 2-1/2 cycles long with a round trip insertion loss of 10.9 dB at the center frequency, and the 40 dB ringdown time was 1.5 ..mu..sec when working into a water load.

ZnO varistors for protection against nuclear electromagnetic pulses

Abstract: The use of ZnO‐based metal‐oxide‐varistor materials in a transient protection device for communications circuits against the effects of nuclear electromagnetic pulses (NEMP) is discussed. The guidelines for such devices call for subnanosecond response time to NEMP and an insertion loss of less than 0.4 dB at 100 MHz. We have measured the response of varistor materials to ∼500‐ps rise time pulses of various amplitudes and durations. No varistor ’’turn on’’ time is evident in these data indicating that the initiation of the highly nonlinear conduction process takes place in less than 5×10−10 s. The insertion loss is calculated from the known high‐frequency electrical properties and found to agree quite closely with the experimentally determined value of 0.1 dB at 100 MHz for varistor chips of cross section 0.025×0.025 cm and thickness 0.01 cm. A packaging configuration for these chips is also described. We conclude that ZnO varistors have application in an NEMP protective device.

Expanded-beam connector design study.

Abstract: A theoretical analysis of an expanded-beam connector is presented, and it is shown that considerable scope exists for optimization of the design. A ray-tracing technique is used to quantify the importance of various parameters in determining the insertion loss. The design guidelines are presented in graphical form, and their usefulness is demonstrated in several examples of practical interest.

A Dual Six-Port Automatic Network Analyzer

Abstract: A 2- to 18-GHz dual six-port automatic network analyzer using diode power detectors is described. An analysis of the calibration technique is discussed in detail. Measurement accuracies of better than 0.1-dB up to 40-dB insertion loss from 2 to 7 GHz are reported. Possible causes of the errors observed at higher frequencies are given.

Branching elements for optical data buses.

Abstract: Asymmetric 4-port couplers and star couplers with 60 ports for multimode fibers are described. The power variations in the output fibers over a −40–+120°C temperature range are reported as is the insertion loss. The optimum output coupling required for minimum path attenuation is computed for a T-bus with symmetric and asymmetric couplers.

Performance of Optically Microwave Switching Devices Coupled

Abstract: The performance of optically coupled microwave switching devices for pulse generation or other applications is detailed The bias dependence of the RF power transfer is presented for a range of operating frequencies, thereby establishing the bias conditions required for a given ON/OFF ratio and insertion loss Limits on peak RF power level and pulse repetition rate, as well as limitations arising from harmonic distortion and shot noise, are also examined

Microwave transmission devices comprising gyromagnetic material having smoothly varying saturation magnetization

Abstract: A multi-port microwave device, such as an isolator or circulator, for transmission of electromagnetic energy in TEM and higher order modes non-reciprocally between parts. The device exhibits low insertion loss, high return loss (low VSWR) and high isolation and is operable over a 100 percent or more bandwidth. The microwave device includes a composite ferrite body between a circuit conductor and a ground plane. The composite ferrite body includes ferrite material having a saturation magnetization gradient for providing different frequency characteristics over the frequency pass band of the device.

A Quasioptical Circuit Technology for Shorttillimeter-Wavelength Multiplexer

Abstract: This paper describes constructions and electrical performances of shortmillimeter-wavelength quasioptical passive circuits using the Gaussian beam mode, i.e., beam mode Iaunchers, polarization-independent beam splitters, circular polarization duplexers, filters, diplexers, and multiplexer. The diplexers were devised to handle wide bandwidths with fairly low loss and to have a sharp cutoff response so that they can be applied to telecommunications systems. Experiments on these components including frequency multiplexers and antenna feed systems were carried out in the 100-GHz band. It is shown that quasioptical circuits are particular useful in reducing insertion loss of multiplexing systems for shortmillimeter wavelengths.

Low-Insertion-Loss Fin-Line Filters for Millimetre-Wave Applications

Abstract: A design theory is described for low-insertion-loss fin-line filters with fin-line gap widths over the total height of the waveguide housing. The theory includes both higher order mode propagation and the finite thicknesses of the dielectric and the metallic fins. An evolution strategy synthesis method yields optimum design data for three- and five resonator-type fin-line filters with several substrate thicknesses. The midband frequencies chosen are about 13, 34, 66, and 75 GHz. Measured minimum insertion-losses in the passband are about 0.2 dB (13 GHz), 0.5 dB (34 GHz), and 1.9 dB (65 GHz) for three-resonator-type filters as an example.

A high performance edge filter for wavelength-division multi-demultiplexer units

Abstract: The theory for realizing edge interference filters, exhibiting minimum polarization at the wavelengths to be separated, despite oblique beam incidence, is extended to versions for any angle. An edge filter (19 alternating layers of SiO 2 and TiO 2 ) for a beam incident at 20° from glass realized through tradeoff between acceptable insertion loss and desired crosstalk attenuation is presented. Due to its steep edge, it is capable of separating the emissions of two led's at close wavelengths. Whereas the reflectance for the wavelength to be passed is almost zero, that for the wavelength to be reflected is almost complete.

Coupler having arbitary impedance transformation ratio and arbitary coupling ratio

Abstract: of EP0066015An impedance transforming coupler (27, 28) is disclosed which may be used as a power divider or power combiner at microwave frequencies. The power division or power combination ratio is arbitrary, and the impedance transformation ratio is arbitrary. These couplers may be used in a circuit to power-combine amplifiers (11, 12). The insertion loss of the circuit is low and the bandwidth is improved by an order to two to one over prior art systems which had separate circuits for matching the impedance and providing power combining. The coupler is optimally a branch line coupler having four curved branches a quarter wavelength long at the center frequency. The output ports are 90 DEG out of phase. Simple formulas are given relating the desired admittances of each of the four branches to k, the desired power coupling ratio, and Y, the desired admittance transformation ratio.

Design considerations and test results of an evanescent switch-attenuator.

Abstract: An implementation technique of an evanescent switch using a cylindrical piezoelectric driver material is discussed. The driver has provisions for fine alignment of the prisms. The selection criteria for the choice of the prism material are evaluated in detail. The measured insertion loss was 10% ± 2%, and these are a 4000: 1 extinction ratio at 10.6 μm between the ON and OFF positions of the switch. The curve showing attenuation vs voltage applied across the piezoelectric driver indicates a large dynamic range for the device as a variable attenuator.

Wide band modem for high speed data transmission

Abstract: A method and apparatus are described for coupling a high-speed data communication modem to a communication line such as a coaxial cable with minimal transmission losses when the modem is not transmitting data. The transmitter coupling apparatus comprises a transformer, first and second transistors, biasing circuits for each of the transistors and a low-pass filter. The data signal to be transmitted is applied to the first transistor which is biased for linear amplification when data are being transmitted and for saturation when data are not being transmitted. The output of the first transistor is applied to the primary winding of the transformer where it is coupled to the secondary winding which is connected in series with the central conductors of the coaxial transmission line. When saturated, the first transistor grounds the winding terminal to which it is connected. The second transistor is biased so as to couple a power supply through the low-pass filter to the other terminal of the primary winding when data are being transmitted and to be non-conducting when data are not being transmitted. The low-pass filter and the first transistor provide a short circuit with respect to high frequency signals across the primary winding when data are not being transmitted. The receiver is likewise transformed coupled with its primary winding being in shunt across the transmission line. As a result of these connections, the output impedance of the transmitter can be made small enough so that the modem insertion loss is about 0.2 db.

Optical mode conversion using chirped gratings

Abstract: A design is presented for a 3 dB TE0-TE1 optical waveguide mode convertor using a chirped grating. Devices were fabricated in Ti in-diffused lithium niobate by ion beam etching the grating pattern into the waveguide surface. TE0-TE1 mode coupling was observed experimentally with an insertion loss of 1.5 dB.

Low-Loss, Low Ripple SAW Filters Using Group-Type Unidirectional Transducers

Abstract: Surface acoustic wave (SAW) filters using group-type unidirectional transducers on LiNb03 have been built with 5 dB loss and 0.01 dB in-band ripples. An impulse model is used to synthesize the transducers and calculate the values of the tuning elements for matching and phase shifting. The model agrees well with experimental results. Filters were tested at center frequencies of 360 and 650 MHz with fractional bandwidth of about 3%. The differences in filter characteristics for both Y-2 cut and 128 -rotated Y-X cut LiNbOJ are examined. By proper weighting of the transducers, proper fabrication control and careful choice of the matching elements, the insertion loss can be as low as 5 dB, the ripples as low as 0.01 dB (peak-to-peak) and the out-of-band-rejection as high as 40 dB.

94-GHz Beam-Lead Balanced Mixer

Abstract: Using a newly developed GaAs beam-lead diode, we have developed and evaluated a balanced mixer at 94 GHz. The various components of the mixer were separately optimized using carefully designed low-frequency model studies as our primary design aid. These studies included the determination of guide impedance and guide wavelength for suspended stripline, and optimization of a waveguide to suspended stripline transition, low-pass filters, and diode location. This 94-GHz mixer exhibits an average single sideband (SSB) conversion loss of 6.2 dB over a 6-GHz RF bandwidth. Together with a bipolar IF amplifier, the system exhibits a 4.5-5.1-dB double sideband (DSB) noise figure over a 50-700-MHz IF bandpass. LO-to-RF isolation was greater that 27 dB over this range of operating frequencies. Finally, severe environmental test were successfully performed on the mixer between sucessive electrical characterization.

Coupler Design in Open Dielectric Waveguide with Web Registration

Abstract: The design and evaluation of an open dielectric waveguide 3 dB coupler with web registration is described. The design includes the selection of waveguide permittivity, size and shape. This design achieved 3 percent bandwidth with 0.7 dB insertion loss, and greater than 22 dB isolation.

Optical branching filter

Abstract: PURPOSE:To improve the attenuation of near-end crosstalk with out reference to an increase in insertion loss, by composing an optical branching filter of an optical filter and >=2 kind of optical media differing in refractive index. CONSTITUTION:In an optical branching filter 5 of a two-wavelength duplex multiplex transmission system which uses 2 kinds of light emitting diodes having different band spectra 21 and 22 as light sources, the optical path wherein transmitted light after passing through a filter 6 propagates until a photodetecting terminal 7 is composed of 0.08/mum wavelength dispersion optical glass 8 and 0.02/mum wavelength dispersion optical glass 9, for example, and signal light reaches the photodetecting terminal 7. The optical glass 8 and optical glass 9 are not bonded together. If light incident to the filter 6 is at 14 deg. and the length of the optical path is of 20mm., the arrival position of unnecessary light, causing near-end crosstalk, at the photodetecting terminal 7 is shifted by about 30mum. Therefore, the attenuation of near-end crosstalk is improved without entailing an increase in insertion loss.