Showing papers on "Insertion loss published in 1969"

Interdigitated Stripline Quadrature Hybrid (Correspondence)

Abstract: lnterdigitated microstrip couplers consist of three or more parallel striplines with alternate lines tied together. A single ground plane, a single dielectric, and a single layer of metallization are used. Thus the approach is eminently suited for monolithic or hybrid thin-film microwave integrated circuitry. Tight coupling is achieved much more easily than with noninterdigitated edge-coupled lines. Fabrication and tolerance problems make it almost impossible to build noninterdigitated 3-dB edge couplers. Also, current crowding at the edges, which can result in high loss, is much less severe for the interdigitated coupler. Previously, tight coupling in directional couplers for microwave integrated circuits has been achieved by broadside coupling, reentrant sections, tandem sections, or branch-line couplers. Some of the disadvantages of these approaches are narrow bandwidth, large substrate area, and the need for multilayer circuitry. A 3dB directional coupler (quadrature hybrid) for S band has been fabricated in microstrip on 40-mil alumina. A single quarter-wave section was used. The hybrid showed a directivity of over 27 dB, a return loss of over 25 dB, an insertion loss of less than 0.13 dB, and an imbalance of less than 0.25 dB over a 40 percent bandwidth.

Design of Surface Wave Delay Lines with Interdigital Transducers

Abstract: Design aspects and tradeoffs are presented for nondispersive, analog Rayleigh wave delay lines with interdigital transducers. Design procedures are based on a one-dimensional piezoelectric transducer model whose applicability has been confirmed by experimental data taken on transducers operating at 100 MHz. For transducers with series inductive tuning, optimum aperture and number of interdigital periods are given for several attractive piezoelectrics, such that insertion loss and phase dispersion are minimized while bandwidth is maximized. High-triple transit suppression designs are given for bidirectional transducers, implying some sacrifice in insertion loss. Using directional transducers, low insertion loss and high triple transit suppression are achieved simultaneously at some sacrifice in bandwidth. Finally, two approaches are given for making with presently available piezoelectrics, bandwidths higher than those attainable with a single tuning inductor. The first of these uses a coupled resonator electrical matching network, while the second employs a transducer with graded periodicity.

Active Filters for UHF and Microwave Frequencies

Abstract: A technique is described for using transistors directly as high-Q inductors at microwave frequencies. Several experimental band-pass filters have been built and tested to verify usefulness of the inductive transistor circuit. Stable filters with unity insertion loss have been realized at UHF. Observations made during temperature cycling show that environmental stabilization can also be achieved. Analysis has been made of noise figure and nonlinear distortion, and supporting experimental data are provided. The inductive transistor circuit is expected to be practical for a variety of small-signal filtering and multiplexing applications.

Slot Line Application to Miniature Ferrite Devices

Abstract: This paper presents preliminary results and conclusions of experimental investigation of the potential usefulness of slot transmission line. Measurement of phase constant, insertion loss, and other general characteristics are presented and compared with theoretical predictions. Transitions from slot to coax and slot to microstrip are described.One of the more interesting characteristics of slot line, the existence of an elliptically polarized H field, is applied in planar ferrite phase shifter design. Experimental data are presented including preliminary latched phase shift results.

Dispersive delay lines using ultrasonic surface waves

Abstract: Surface ultrasonic wave delay lines with dispersive time-frequency characteristics have been made using interdigital electrode arrays with variable element spacings on LiNbO 3 . The devices operate at 60 MHz with low insertion loss and a 3-dB bandwidth over 25 percent. A model has been devised which accurately predicts the phase and amplitude characteristics of the devices. "Weighting" the array to improve the phase characteristic is described.

1.75‐GHz ACOUSTIC‐SURFACE‐WAVE TRANSDUCER FABRICATED BY AN ELECTRON BEAM

Abstract: Surface‐acoustic‐wave interdigital transducers operating at 1.75 GHz have been fabricated on y‐cut z‐oriented LiNbO3 and y‐cut x‐oriented quartz substrates by electron‐beam techniques. The transducers consist of 25 pairs of interleaved aluminum ``fingers'' 0.3 μ wide and 0.7 μ apart. Used as a surface acoustic wave delay line, the insertion loss has been measured to be as low as 25 dB with a bandwidth of 70 MHz for 2.2‐μsec delay. The parameters of the equivalent circuit of the transducer have been measured and agree with the theoretical calculation.

The Generation and Propagation of Acoustic Surface Waves at Microwave Frequencies

Abstract: The generation and propagation of acoustic surface waves is reviewed with particular emphasis on the microwave-frequency range. Theoretical work on optimizing the generation efficiency and the bandwidth of interdigital transducers is compared with recent experimental results. The minimum Iinewidth of 0.9 /spl mu/m which can be produced by optical photolithographic techniques places an upper limit of about 1 GHz on the maximum frequency that can be generated at the fundamental mode. Overtone operation has been used to generate 3 GHz surface waves on LiNbO/sub 3/ but this method has the disadvantage of reduced efficiency plus the complication of volume-wave generation. A better solution for generation above 1 GHz is the fabrication of interdigital transducers by means of electron beam exposure of the photoresist. The surface-wave propagation loss gives a significant contribution to the total insertion loss of delay lines operating at microwave frequencies. Losses of 1.1 dB//spl mu/s and 3.8 dB//spl mu/s at 0.9 GHz and 2 GHz, respectively, have been measured for propagation along the Z-direction of Y-cut LiNbO/sub 3/ by means of a laser deflection method. Larger losses have been observed for quartz. The additional complexities for surface-wave propagation due to the anisotropic single-crystal substrates which are necessary at microwave frequencies are also described.

A Multiple-Diode High-Average-Power Avalanche-Diode Oscillator (Correspondence)

Abstract: This correspondence presents a simple circuit which allows direct combining of the power obtainable from several avalanche diodes. The circuit does not require extremely close matching of dc or RF diode characteristics, and no particular isolating networks such as hybrid combiners are necessary. CW power output exceeding 4 watts at 7 GHz and 3 watts at 9 GHz has been demonstrated in a device employing five diodes. The number of diodes which can be combined using this technique is limited by geometric and heat sink considerations. Descriptions of typical single-diode and multiple-diode oscillators are given along with equivalent circuits. The circuits employ resistors or resistor networks to suppress low-frequency oscillations and undesired resonances which occur when several oscillators are coupled together. Negligible insertion loss is incurred at the design output frequency. Measured performance is given on similar single- and multiple-diode oscillators. Data include frequency, power, AM noise, FM noise, temperature, and loaded Q.

Unidirectional surface wave transducer

Abstract: A surface wave transducer is described which radiates acoustic power in essentially one direction. Using Y cut, Z axis propagating lithium niobate and unidirectional transducers, a delay line has been constructed that exhibits 6.5-dB insertion loss and 52-dB triple-transit echo suppression at 106.5 MHz.

Acoustic surface wave coupling across an air gap

Abstract: Transfer of acoustic surface waves between two noncontacting surfaces by means of passive, co‐directional piezoelectric coupling is achieved in LiNbO3. Minimum coupling loss is less than 3 dB. When the surfaces are maintained parallel, periodic variation of insertion loss with coupling length is observed. Measurements are in close agreement with predictions using coupled mode theory. A 100‐MHz delay line with a mechanically variable, nondispersive differential delay of 6.1 μsec and a total insertion loss less than 17 dB which utilizes this coupling mechanism is reported.

Piezoelectric Semiconductor Acoustic Delay Lines

Abstract: The delay of signals for microsecond time periods in monolithic structures using piezoelectric semiconductors is described. Thin resistive regions were formed by the diffusion of compensating impurities in semiconducting crystals of ZnO, CdS, CdSe, and GaAs and used as transducers for the excitation and detection of acoustic waves in the 30-MHz to 1.0-GHZ region. Time delays from 200 ns to 5.0 /spl mu/s were achieved using simple acoustic transmission structures. Insertion loss values less than 10 dB were achieved in ZnO for microsecond delays up to 600 MHz. Frequency-tuned bandwidths of 70 to 90 percent were obtained. The frequency-loss characteristics of the delay structures could be quantitatively related to a simple theoretical model. The performance characteristics of representative matched and packaged acoustic delay lines is described.

A 50 Hz–250 MHz computer-operated transmission measuring set

Abstract: A computer-operated transmission measuring set has been developed for the 50 Hz to 250 MHz frequency range. Use of the computer in this system has significantly effected the test set design and the measurements obtainable. Compared with previously available transmission measuring sets, the computer-operated set increases speed more than 300 : 1. This speed, along with state-of-the-art accuracy and increases in operating range, flexibility, and convenience, enables the set to be used for types and quantities of measurements previously not practical. It has already been applied to laboratory and production testing with resulting improvements in the quality and reliability of manufactured product designs. In addition to the directly measured quantities of insertion loss and phase, the set provides insertion delay, impedance, and two-port parameters as derived quantities. The two-port data conversion program provides H, T, Z, G, T, S, ABCD and ABCD−1 parameters with a number of useful options. Results of transmission measurements, impedance measurements, and two-port measurements are presented. Some of the error mechanisms and means of measuring them are discussed. Further development of centralized measuring facilities, with the computer operated set as a basic element, is discussed.

Computer Design of Filters with Lumped-Distributed Elements or Frequency Variable Terminations

Abstract: A method for realizing prescribed insertion loss characteristics is presented which is applicable to mixed distributed lumped parameter systems, as well as to transmission line structures which operate into resistive frequency variable terminations. The method utilizes scattering matrix renormalization and is implemented by a computer program. Examples given include capacitor and inductor loaded transmission line sections, as well as a TEM filter terminated in TE/sub 10/ wave impedances. The insertion loss characteristics have equal ripple passband behavior.

Microwave Silicon Windows for High-Power Broad-Band Switching Applications

Abstract: Theoretical and experimental results obtained with a novel silicon window utilizing double-carrier injection to achieve high-power broad-band microwave switching are presented. The device consists of a wafer of high-resistivity silicon inserted across a waveguide with thin-line junction structures oriented orthogonal to the RF electric field. These line junctions provide hole-injecting contacts on one face and electron-injecting contacts on the other. With zero bias, the window appears as a thin low-loss dielectric slab, and the RF signal is transmitted. With forward bias, the window appears as a highly conductive slab due to the injected electron-hole plasma, and the RF signal is reflected. Calculations show that X-band windows 8 mils thick have a switching ratio of 0.5 to 15 dB if the resistivity change is from 300/spl Omega//spl dot/cm to 1/spl Omega//spl dot/cm. X-band windows have been fabricated having an insertion loss as low as 0.3 dB and a VSWR below 1.3 in the transmission state and an isolation as high as 18 dB (5 amperes at 1 volt) in the reflecting state. These characteristics are maintained across the complete waveguide band (8.2 to 12.4 GHz). Windows have been tested to 50-kW peak power without degradation in switching characteristics. The main advantages of the window over conventional p-i-n diodes are an order of magnitude or more increase in power handling (50 kW peak measured while 300 kW is predicted compared to 5 kW for a single p-i-n diode X-band high-power switch), full guide bandwidth operation (compared to 10 percent bandwidth for the conventional p-i-n), simpler bias circuitry (no reverse bias is required in the transmission state), and higher temperature operation (since no reverse voltage is needed).

Method and system for adjusting electrical components using alternately applied signals

Abstract: A crystal filter or similar electrical component is adjusted by application to the filter of a characteristic adjusting medium, such as evaporated or sputtered gold, in order to provide a desired differential insertion loss with respect to output signals corresponding to two input signals generated at two frequencies of interest. The two input signals are applied sequentially to the filter with the signal levels of the input signals calibrated to differ by a quantity equal to the desired differential insertion loss. An initial calibration, utilizing a signal attenuator, provides this differential. Treatment then occurs, with the output of the crystal being continuously monitored by a signal amplitude measuring device. An AC monitoring signal, representing the alternating output signal levels corresponding to the sequentially applied input signals, is generated from the signal amplitude measuring device. A phase reversal in the AC monitoring signal is sensed by a phase detector, which generates a control signal to terminate the treatment operation. The phase reversal occurs at the instant that the desired differential insertion loss value is attained.

Miniature broad band low pass filters with multiturn tape wound inductors

Abstract: A miniature broadband high frequency low pass filter having at least one multiturn tape wound core inductor and at least one ceramic capacitor whereby the resultant filter exhibits improved insertion loss characteristics even in filter applications having certain amounts of DC or low frequency current passing therethrough.

Active Interference Cancellation System.

Abstract: : The report discusses the principles and performance of an active Interference Cancellation System fabricated for UHF communication applications. The system employs a synchronous cancellation technique for the suppression of adjacent channel interferences. Two experimental models were fabricated for checkout in operational situations where transmitting sources are collocated with the receiver. The Interference Cancellation System (ICS) is designed such that no existing equipment modification is necessary for the cancellation of any selected interference. The system involves linear processing. The experimental models provide 80 dB of suppression to AM without tuning in the 225 to 400 MHz band. They are capable of simultaneously suppressing two interfering signals with levels as high as +20 dBm and frequency separations as low as .025 MHz. The insertion loss for the desired signal is less than 5 dB. (Author)

Low insertion loss directional detector

Abstract: The directional detector includes input and output terminals connected by a bridge resistance R1 . A pair of diagonal resistances R2 , R3 having the same impedance as the transmission line to which the device is connected are connected to a common node and across to each of the input and output terminals respectively. A third resistance R4 is connected from the common node to ground node which also connects the ground side of the input and output terminals. The resistances R1 and R4 are related by the equation Zo2 =R1 R4 . Otherwise, R1 , R4 can be chosen arbitrarily to provide specified insertion insertion loss and attenuation. A detecting element is connected in parallel across one of the diagonal resistors for providing a voltage indication of power reflected into the node to which that diagonal resistance is connected, either input or output. Typically, the detecting element is a high frequency, high-impedance diode connected in series with a resistance and DC blocking capacitor to provide enhanced flat frequency response over a wide bandwidth. Another embodiment of the invention utilizes printed circuit techniques in stripline to obtain higher frequency of operation.

Equivalent Circuit and Loss Invariant for Helicon Mode Semiconductor Devices

Abstract: A basic nonreciprocal two-port component in the HF range is considered consisting of two spatially orthogonal coils wound on an indium antimonide slab. A dc magnetic field is impressed perpendicular to the axes of the coils. Local helicon mode theory, assuming a single type of carrier, is used to derive the frequency-dependent network matrix of the device. From this matrix a broadband equivalent circuit is synthesized, which contains one gyrator. The resultant network structure is then analyzed to arrive at a loss invariant or figure of merit for the nonreciprocal device and the invariant is found to be frequency independent. This loss invariant is used to calculate the minimum possible insertion loss of an isolator formed by imbedding the helicon mode element in the most general lossless reciprocal circuit. The minimum loss is shown to be Minimum insertion loss = 10 \log \left( 1 + \frac{1}{u^{2}} \right) dB , where u is the tangent of the Hall angle in the InSb slab. Two-port experimental measurements were made (using a low-frequency embodiment of a microwave directional coupler) over the frequency band 5-15 MHz to verify the equivalent circuit and the value of the invariant. These data provided reasonable verification of the equivalent circuit, the invariant, and the minimum loss figure. A circuit for a minimum insertion loss isolator was constructed, and at fields of 2600 and 5600 gauss the measured minimum insertion loss at room temperature was found to be 2.8 and 1.5 dB, respectively. This data compares with the theoretically predicted figures of 3.1 and 1.0 dB. These results are all under infinite isolation conditions. A derivation is given to show the optimum benefits to be obtained by trading reduced isolation for improved insertion loss. Finally, the theory of invariance is employed to derive expressions for the minimum insertion loss of a helicon mode gyrator and three-port circulator.

Some Magic Tees with 2 to 3 Octaves Bandwidth

Abstract: Techniques have been developed which extend the frequency range of ring magic tees to 7:1 or more. Experimental 250 to 1000 MHz ring magic tees have been built with 0.6 db insertion loss (above the 3 db power split), 0.2 db amplitude balance, 2/spl deg/ phase balance, and a 1.5:1 maximum VSWR over the 2-octave frequency range. An experimental 300 to 1800 MHz ring magic tee has been built with the performance shown in Figure 5. Figure 1 shows schematically the basic ring magic tee, and a typical curve of VSWR versus electrical length. The four transmission lines are nominally 70.7 ohms characteristic impedance for a maximally flat design. If the line impedances are made 65 ohms, then the basic design has an equal ripple 1.18:1 VSWR bandwidth of one octave.

Dielectric Constant and Loss Tangent Measurement of High-Temperature Electromagnetic Window Materials.

Abstract: : The research performed in the development of a new technique for measuring the complex permittivity of electromagnetic window materials from ambient temperatures to 4500F is described in this report The measurement technique employs a focused, free-space microwave bridge and a rotating disk sample heated on one side by oxy-acetylene flames Provisions were made for eliminating flame from the microwave measurement area Data are included to substantiate the feasibility of the measuring technique Surface temperatures of the sample were measured by optical pyrometers, and internal temperatures were determined by embedded thermocouples Dynamic measurements were made of the sample insertion phase and insertion loss A transient heat conduction analysis was used to determine temperature profiles within the sample, and the electrical transmission data were correlated with the temperature profiles to give dielectric constant and loss tangent as functions of temperature The relative dielectric constant versus temperature function of high purity slip-cast fused silica (85 percent density) is a segmented straight line (Author)

Microwave ferrite film circuit configuration

Abstract: DESCRIBED IS MICROWAVE MINIATURIZED SIGNAL PROCESSING CIRCUITRY FOR RADAR AND THE LIKE APPLICATIONS EMPLOYING FERRITE FILMS CAPABLE OF EFFECTING A PHASE SHIFT IN WAVE ENERGY PASSING THROUGH THE CIRCUITRY, AND WHEREIN THE INSERTION LOSS OF THE DEVICE IS MINIMIZED. THIS IS ACCOMPLISHED BY PROVIDING A STRUCTURE WHEREIN THE WAVE ENERGY NEED NOT PASS THROUGH A CERAMIC OR THE LIKE SUBSTRATE, BUT RATHER IS CONFINED ESSENTIALLY WITHIN THE FERRITE MATERIAL ITSELF.

Some RF Characteristics of Bonding Systems

Abstract: The measurement of bonding impedance has been typically limited to dc or to relatively low (<20 MHz) frequencies. However, the impedance characteristics of the bonding system should not be simply ignored at higher frequencies. To do so may be neglecting a serious source of electromagnetic interference. This paper presents techniques for the measurement and interpretation of bonding impedance characteristics through the VHF region. A measuring device based on the insertion loss technique is described. Calibration curves of typical models of this device show its usefulness for measurements up to 400 MHz. The application of this device to the measurement of bonding systems in field installations is also explored. From data obtained with the insertion loss device, an equivalent circuit of a typical bonding system is developed which incorporates the contributions of the equipment case as well as those contributions of the bonding straps to the overall impedance characteristics. It is shown that typical bonding systems exhibit regions of parallel resonance which are often at relatively low frequencies. Within these regions, the impedance of the bonding path is often very high. Because of this high impedance, the equipment case can act as a very effective antenna. Evidence is presented to show that the case voltages induced by a radiated field in the resonant frequency region may increase as much as 25 dB for a bonded system over a system that is not bonded.

Active Impedance Matching for Microwave Acoustic Delay Lines (Correspondence)

Abstract: Some experimental results are presented which demonstrate the feasibility of using transistor circuits (of the inverted common-collector type) as elements in impedance-matching networks for microwave acoustic delay lines. This technique is shown to offer the possibility of realizing matched delay lines having both low insertion loss and low spurious triple-transit echo level.

High frequency switch

Abstract: A switch for conducting or interrupting the flow of current through spaced electrical conductors which introduce a minimum impedance discontinuity and insertion loss when operating in its current-conducting mode. Rapid initiation and termination of current flow is achieved by rapidly displacing a pool of electrically conducting liquid into and out of conducting position, respectively.

N-input aperiodic hybrid coupler

Abstract: An aperiodic coupler having any number of inputs and comprising the same number of two-wire lines, each associated with a high permeability magnetic core. Its insertion loss is negligible and it has substantial decoupling between any two inputs.