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The purpose of the program is to continue the research on 10.6 micrometer image upconversion detectors and to determine the feasibility of developing a 10.6 micrometer range gated upconversion imaging laser radar receiver with 150 by 150 resolution elements. An experimental model image upconverter capable of real time direct viewing has been assembled. Imaging characteristics such as resolution, field of view, and the upconversion efficiency of the experimental model were measured by arranging the model in the Fourier space and the image space configurations. Analysis describing the optical transfer function of the Fourier space configuration and the line spread functions of non-Fourier space configuration are presented. The crystal birefringency is included in the analysis. Calculation of resolving power and some consideration on the object optics are also included. Measurements of conversion efficiency and realistic estimates of practically achievable efficiency are presented and realistic values for the SHG d coefficients of proustite are considered., See also AD741227.

The Seventh Communications Division of the International Civil Aviation Organization (ICAO) has recommended the adoption of a digital code for automatic height transmission via the AIR TRAFFIC CONTROL RADAR BEACON SYSTEM. Salient features of the code are (1) One-hundredfoot digitizing increments; (2) Range from -1000 feet to +126,750 feet; (3) Compatibility with limited- capability 500-foot incremented code; (4) Unambiguous unit-distance characteristic; (5) Height transmission with respect to a fixed datum of 1013.2 millibars (29.92 inches of mercury). The code, as recommended by ICAO, is tabulated for height increments in increasing numeric order and for the equivalent octal Mode 3/A reply in increasing numeric order. The PULSE POSITIONS column lists the timesequence assignment of the pulse-transmission reply, and the HEIGHT CODE POSITIONS column gives a rearrangement of the code information in significant-digit sequence. Five-hundred-foot increments are extracted from the tables by omitting the C information pulses for the appropriate integer multiple of 500-foot height.

Research was continued on the development of a low noise, small signal, varactor diode parametric amplifier operating over a range of 2 to 4 gc. Two single-diode varactor mounts, each having a 40-percent instantaneous bandwidth, were cascaded to yield an overall gain of 10 db from 2 to 3 gc (3-db points). The noise factor of these combined amplifiers varied linearly from 1.8 db at 2 gc, to 3 db at 2.8 gc. The noise factor above 2.9 gc peaked very sharply to about 5.5 db. The reason for this peak is not yet apparent. The configuration of the final engineering model was fixed-four stages will be used and the package will accommodate either the balanced or unbalanced varactor mount.

Elements of the basic system for spotting airborne objects are described, and by means of a model radar set, the effects of such parameters as frequency, pulse width and repetition frequency, bandwidth of receiver and antenna beamwidth are evaluated, particularly with respect to range. Use of doppler effect and moving-target indicators described, also beacons. Principles of tracking radar.

The UHF Same Frequency Repeater suffered from low usable isolation because of the limitations in manually tuning the matching network of a hybrid to equal the constantly varying impedance of an antenna. Operation of the repeater was further hampered by the adjustments necessary to accommodate band switching. An Automatic Impedance Matching (AIM) network was developed to continuously adjust the impedance of the matching network to automatically maintain a high isolation between the transmitter and receiver ports of the hybrid. A common RF switch was also designed as part of this program so that channel switching could be accomplished with only one control, without the need to make readjustments. RFI due to incomplete transmitter shutdown was eliminated by the addition of a coaxial relay. Other sources of RFI were eliminated by replacing most RF cables with double-shielded coax., Supplement 1 to Rept. no. AIL-4190-2 dated Nov 69, AD-865 283.

This report describes an experiment that was performed to evaluate a new low-angle tracking (LAT) radar technique which uses array antenna technology. The process enables the radar to track targets in elevation in the low-angle region between one beamwidth and the horizon. The technique uses the array facility to form two beams, and a two-channel receiver system which forms the ratio of the signals from each beam. By design this ratio is proportional to target elevation angle. The antenna patterns are designed to suppress the multipath signal energy, but residual image signal energy entering the receiver is processed with the target signal without degradation of system performance. This technique was implemented and tested on an over-water range using an aircraft as the test target to gather data and evaluate system performance under varying reflective surface conditions. The system operated at 5.5 GHz and used a 12-foot array aperture. Tracking data was collected between elevation angles of 5 to 20 millirads with one-tenth beamwidth accuracy. A description of the flight test is given and a summary of the experimental data is presented. (Author)

The report describes a theoretical investigation of field effect transistor (FET) amplifiers and mixers. An experimental investigation of the FET amplifier was performed at VHF (60 MHz), and of the FET mixer at MF (500 kHz) and HF (20 MHz). The theoretical and experimental investigation was performed on four junction FET (JFET) devices (2N3823, 2N4416, CM647, CP650) and one Metal Oxide Silicon FET (MOSFET) device (3N152). The emphasis of the investigation was on the spurious signal generation and interference effects. A large signal model is developed for the FET and from this model, equations are derived that enable the circuit designer to predict levels of RFI in his circuits. Measurements were made of the significant interference effects in FET amplifiers and mixers and a comparison of the results showed good agreement. In addition to the discussion of RFI performance the tradeoffs between RFI performance and power gain, noise figure, and bandwidth are discussed. These considerations enable the circuit designer to make the necessary compromise to obtain a circuit that most nearly satisfies electromagnetic compatibility and system electrical performance simultaneously. (Author)

A Target Simulator was designed, built, and installed in the Signal Processing Test Facility (SPTF) located at the Floyd Test Annex, RADC, Rome, N.Y. It is used to generate fixed and moving targets for evaluation of the performance of the high-resolution Signal Processing Subsystem (SPSS). The fixed targets are delayed replicas of the transmitted radar signal and are introduced into the radar receivers at simulated ranges of approximately 100 and 500 miles. The moving target is internally generated by the target simulator and is used to test the performance of the range tracking subsystem of the SPSS. (Author)

The report covers research on microwave superconducting receiver techniques. An analysis of Josephson mixer operation, including characterization into a mathematical model suitable for analytical and computer study and a rigorous formulation of the generation of steps due to microwaves in the DC I-V characteristic, has been carried out. Experimental observation of the Josephson mixing action at 10 to 15 GHz has been obtained and is in agreement with the theory developed. The conversion loss, noise factor, and sensitivity of Josephson mixers have been measured. Using a point contact junction at 13 GHz, a minimum detectable signal of -90 dbm/MHz (measured) and -105 dbm/MHz (corrected) was obtained. Superconducting, miniature microstrip resonators operating at 10 to 15 GHz have been constructed using vacuum-deposited lead on low-loss sintered alumina substrate. Unloaded Q's (at 14.3 GHz) as high as 200,000 and 500,000 have been measured at 4.2 and 1.8 K respectively. The vacuum deposition technique used would permit the simulataneous fabrication of large numbers of miniature multielement filters and preselectors with low insertion loss and good skirt rejection. (Author)

A packaged infrared 10.6-micron heterodyne receiver was developed for radar application. It combines sensitivity approaching the quantum-noise limit with gigahertz IF bandwidth. Signal processing electronics was also provided for search and acquisition of the doppler-shifted radar return signal, and other functions. The receiver has as its principal components a cryogenically cooled Ge:Cu infrared mixer element, and associated broadband IF preamplifier, IF and signal processing electronics, and peripheral monitor and control electronics. The receiver is suitably packaged for operational use in a 10.6-micron pulsed radar system. Design considerations and measured receiver characteristics are presented. Receiver noise properties for IF frequencies up to 1200 MHz and mixer noise characteristics were measured. The measured noise equivalent power was 8.1 x 10 to the minus 20th power w/Hz at 1.4 kHz, less than 1.5 x 10 to the minus 19th power w/Hz from 10 to 800 MHz, and less than 2.25 x 10 to the minus 19th power w/Hz up to 1200 MHz. (Author)

The report covers research into superconducting receiver techniques concerned principally with the development of superconducting microwave mixers utilizing the Josephson effect and superconducting, ultra-high Q, microwave resonators, filters, and preselectors. The theory of operation of Josephson mixers, characterization into a mathematical model suitable for analytical and computer study, and a rigorous formulation of the DC I-V characteristics has been obtained. Experimental observation of the Josephson mixing action has been observed which is in excellent agreement with the theory developed. Superconducting, miniature microstrip resonators were built and the results of experimental determination of their Q's is reported. (Author)

The program has demonstrated the following technological elements. A structure to support a 3 x 3 configuration of high performance 10.6 micrometer mixer elements. An array of microlenses that generate receiving antenna beams in registration and crossing each other at a point 3 dB below their peak responses. A mixer-preamplifier combination with measured NEP values of better than 2 x 10 to the -19th power watts/Hz from 10 MHz to 1500 MHz. A microstrip cabling technique to handle the microwave IF signals detected by the infrared mixers. Adequate thermal conductivity in the array structure to extract the heat dissipated by the local oscillator beam and dc bias current. At least 30 dB of electrical isolation at 1500 MHz between adjacent cooled mixer elements.

The report covers the development of an X-band, integrated, low-noise sweeping receiver or Integrated Microwave Amplifier-Converter (IMAC) covering 8-10 GHz. Based on a system tradeoff study, the following components were selected for the IMAC: Wideband, circulator-coupled, tunnel diode RF amplifiers; varactor-tuned, tunnel diode oscillator; image-phased balanced mixer; wideband IF amplifier; narrowband IF filter. The report details the design, construction, and testing of the above components of the IMAC and includes a study of system reliability. (Author)

This research, primarily for the study and investigation of techniques leading to improved multicouplers, was part of the long range plan to improve the compatibility of collocated transceivers during adjacent channel operations. Of primary significance was the work done on superconducted resonators in the 225-400 MHz band. The information derived from this effort can be used as a basis for the design of diplexers utilizing superconducted resonators which, while somewhat costly to operate, may be required to solve specific interference problems on critical communication links. (Author)

A report is made on a program to demonstrate the feasibility of a 10. 6-micron coherent receiver array with 1.5-GHz IF bandwidth, 3 X 3 elements with -3 db antenna-beam crossovers, and near quantum-noise limited sensitivity. The two primary areas of investigation were: (1) coherent array development, which includes the formulation of an analytical model of a coherent multiple-beam array, computer-generated antenna patterns, laboratory verification of these patterns, and formulation of diffraction-limited image dissection techniques, and (2) mixer development, which included achieving Ge:Cu mixer response to 1.43 GHz (with NEP equal to, or less than 1.5 X 10 to the 19th power Hz/watt over this band), analysis of wideband photovoltaic mixing, measurements of 9 mixers of various types, and continued development of a single amplifier to cover the band from 10 MHz to 1.5 GHz.

This report describes a study and investigation of the split aperture technique for antenna intrabeam signal processing. This technique makes use of phase and amplitude information received on a number of subapertures of a large aperture antenna, in conjunction with a priori information on the number of targets in the antenna beam, to provide an improvement in angular resolution. A computer simulation is described which estimates the location of the multiple targets as a function of the relative target amplitudes and phases, S/N ratio, position in the beam and system measuring accuracy. Results obtained from an experimental setup to simulate two targets are presented and compared with the calculated results. Suggestions for possible system implementations are given. Section 1 presents a historical development of the problem, Section 2 a theoretical formulation of the split aperture technique, Section 3 the experimental measurements, and Sections 4 and 5 the conclusions and recommendations. The computer programs and signal processing techniques are presented. (Author)

A theoretical and experimental investigation of circuit techniques was conducted to provide circuits with minimum interference susceptibility for receiver application. The circuits considered are solid-state circuits for predetection functions in receivers, operating in the frequency range from 1 MHz to 10 GHz, and include bipolar transistor amplifiers, field-effect transistor amplifiers, parametric amplifiers, tunnel-diode amplifiers, crystal-diode mixers, and varactor-tuned filters. Investigations were also conducted to determine the nonlinearities and RFI characteristics of microelectronic receiver circuits and the Hall-effect mixer. Measured and predicted results of intermodulation, harmonic distortion, and cross-modulation are shown graphically for the circuits investigated. Techniques to minimize interference susceptibility and performance tradeoffs are discussed and are illustrated by developed circuits and measured data. (Author)

This report describes an investigation of radio frequency interence (RFI) in tunnel-diode amplifiers. Equations are derived which predict the harmonic and intermodulation power levels, or rejection of harmonics and intermodulation, and the percent cross-modulation as a function of tunnel-diode and circuit parameters. The parameters that must be known to make use of the equations are the diode peak voltage and current, bias voltage, source impedance, and amplifier gain. A push-pull, tunnel-diode amplifier was developed to demonstrate the feasibility and the advantages of a balanced amplifier. Measurements were made of the significant intermodulation and cross-modulation interference effects and then compared with the predicted effects. The results agreed with the theoretical predictions. (Author)

This report concerns the investigation of methods and techniques as well as the selection of materials and the evaluation of electronic components used in the final model. During this period, both types were re-designed several times in order to meet the electrical, thermal, and mechanical requirements of the program. All considerations which led to the adopted designs are presented and discussed. For detailed data, reference should be made to the four previously issued quarterly reports. Also described in this report are the difficulties encountered, their solutions, and the reasons for not meeting some of the objective specifications such as warm-up for the N13 oven.

Criteria are presented for the design of an optimally reproducible, low-cost, high-performance, parametric amplifier for use in electronically steerable radar systems. The basic amplifier configuration is that of a circulator-coupled balanced varactor parametric amplifier with the varactor pair connected essentially at the ferrite junction reference plane at the amplifier port of the circulator. A new signal frequency equivalent circuit of a pumped varactor pair has been presented with all circuit element values characterized in terms of fundamental varactor quantities. An existing design theory for a linear phase parametric amplifier has been extended to yield gain- and phase-bandwidth limitations and required circuit element values in terms of fundamental varactor quantities. The theory indicates that the gain-bandwidth and phase-linearity objectives can be met using two cascaded 10-db linear phase amplifier stages, each using a balanced pair of silicon varactor diodes of quality factor 21, a self-resonant frequency of 14.5 GHz, a nonlinearity ratio of 0.3 and a pump frequency of 17.87 GHz. A prototype model of a three-port stripline circulator was constructed for use in this amplifier. Its performance has been optimized with respect to ferrite material and magnetic field intensity for a suitable, though not sufficiently broad-band impedance characteristic over the 3.1 to 3.7 GHz range. (Author)

Design criteria are presented for the attainment of high-performance, low-cost parametric amplifiers for application to electronically steerable radar systems. A detailed comparison is made between the single-diode and balanced parametric amplifier configurations in order to establish optimum parameter requirements. It is shown that the balanced parametric amplifier offers the greatest potential for achieving the overall requirements of this program. The balanced paramp approach requires a varactor quality factor (M) of 15 to 20 GHz, and a corresponding idler frequency from 11.6 to 14 GHz. (Author)

Antenna systems consisting of two concave reflectors illuminated by a planar feed cluster were investigated. The primary reflector was a segment of a rotationally symmetrical paraboloid; the secondary reflector was on the opposite side of the primary focus and concave toward the primary focus. Its contour and size were variable; the planar feed cluster was normal to the axis of the primary reflector and located near its focus. These reflectors and feed were arranged in an offset configuration so the aperture blocking, usually caused by the secondary reflector, was eliminated. A computer study of the system geometry was extended to three dimensions (pervious work had studied the two-dimensional geometry) and a model antenna system was built and tested. The size, contour, and position of the secondary reflector were investigated in relation to the system's ability to scan, zoom, and correct for distortion. A model of this antenna system demonstrated good scanning and zooming ability as a result of linear and second-order phasing across the feed. The two-reflector geometry was too complex to permit any correlation of results from three-dimensional systems with results from two-dimensional (or cylindrical) calculations, even though the correlation has been demonstrated to be excellent for simpler cluster-feed systems. However, the extended analysis (three dimensional) led to a simple antenna design that provided the optimum results in both scanning and distortion correction; the simpler two-dimensional analysis had previously led to more complex geometries resulting in different antenna designs for each capability.

This report describes an experimental and theoretical study of Hall-effect mixers for use in receiver applications above 10 MHz. Equations were derived for conversion loss, noise figure and intermodulation. It was shown that the performance of a Hall-effect mixer degrades as frequency increases because of dissipation limitations in the Hall element. Thus, above 10 MHz, the conversion loss and noise figure of the Hall-effect mixer are extremely poor when compared with crystal diode mixers. It was also shown that the spurious responses of a Hall-effect mixer are comparable to those in a crystal-diode mixer for equal conversion loss in both devices. These and other considerations lead to the following conclusions: (1) The Hall-effect mixer can be made competitive with conventional mixers only if a material can be developed which would provide efficient operation without the need for low-temperature operation. (2) A Hall-effect mixer using existing materials for the Hall plate should not be considered as a preferred circuit for receivers at frequencies above 10 MHz.

This program called for the development of an ultra low noise broadband traveling wave Maser. This MASER had four separate electronic devices incorporated into the overall package; the TWM superconducting solid state limiters, superconducting solenoid and a superconducting RF pump source. A TWM was designed which had an inherent bandwidth of 300 MHz and a noise temperature of less than 9 degrees K. A low level power limiter using the mechanism of impact ionization in bulk germanium was demonstrated. The magnetic field for the TWM was provided by a superconducting solenoid that can be switched into a persistent mode of operation. Theoretical studies were conducted to determine the feasibility of the use of superconducting tunnel junctions as an RF pump source for the MASER. Present state-of-the-art techniques were not considered adequate for accomplishment of the desired design parameters. Conventional klystrons were therefore provided for the pumping circuitry. (Author)

The report covers plans for feasibility demonstration, prototype systems development, and limited production option., See also AD-772 595.

The report details technical aspects of AIL proposed MLS hardware development. Part 1.0 Volume 1.1 discusses the technique analysis. Part 1.0 Volume 1.2, Books I and II cover plans for feasibility demonstration, prototype systems development, and limited production option. Part 3.0, Volume 3.1, Books I and II present analysis of Critical Technical Areas. Part 3.0, Volume 3.2 covers the System Technique Summary, Functional Requirements Summary, and Detailed Feasibility Hardware Specifications. (Author), See also AD-772 598.

Part 3.0, Volume 3.2 covers the System Technique Summary, Functional Requirements Summary, and Detailed Feasibility Hardware Specifications., See also AD-772 595 and AD-772 597.

Part 3.0, Volume 3.1, Books I and II present analysis of Critical Technical Areas., See also AD-772 595 and AD-772 597.

Part 1.0 Volume 1.2, Books I and II cover plans for feasibility demonstration, prototype systems development, and limited production option., See also AD-772 596.

Part 3.0, Volume 3.1, Books I and II present analysis of Critical Technical Areas., See also AD-772 596 and AD-772 598.

The purpose of the program performed under this contract is to continue the research on 10.6-micrometer image upconversion detectors and to determine the feasibility of developing a 10.6-micrometer range-gated upconversion imaging laser radar receiver with 150 by 150 resolution elements. To meet the program objectives, the following areas were studied: Experimental determination of the effect of a diverging pump on image resolution for the image space configuration upconverter system and comparison of the results with analytical prediction; Analytical determination of the effect of birefringence and a truncated pump beam on image resolution; Development of techniques to handle power dissipation inside the nonlinear crystal; and, Investigation of techniques for improvement of optical efficiency.

The instruction manual is for a monitor unit designed and built to be used in conjunction with slightly modified conventional VOR monitor. It employs phase-lock loops to extract the precision signals and a programmed selector unit to sequence among eight field detectors in order to detect any conceivable ground-station fault. (Author), See also Volume no. 2, AD-666 576.

The operating specifications (modulation percentages, tolerances, bandwidth, etc.) of the precision multilobe VOR (PVOR(M)) are established. The criteria for selection of monitor field-detector positions and monitor tolerances are explained, and the flight test/computer program used to establish them is described. A simplified broad-band PVOR(M)/Doppler-VOR feed system to replace the feasibility model PVOR(M) feed system was developed during this program. It achieves isolation of the Doppler and PVOR(M) signals by means of high internal SWR's and lossy terminations rather than the frequency-sensitive coaxial hybrids of the original model. (Author), See also AD-666 576.

The volume is an instruction manual for PVOR signal generator, employing digital and linear integrated circuits, developed for test and alignment of PVOR(M) receivers. This unit generates the conventional VOR signals as well as the complete PVOR(M) signal spectrum, and exhibits a PVOR(M) azimuthal accuracy of better than 0.01 degree. (Author), See also Volume 1, AD-666 575.

The Precision VHF Omnirange (PVOR) consists of an International Civil Aviation Organization (ICAO) standard VOR that has been modified to transmit additional precision multilobe bearing information on the same channel. A standard airborne navigation receiver with a PVOR converter automatically resolves the ambiguities of the multilobe signal. An unmodified navigation receiver continues to use only the standard portion of the signal with no degradation in performance. Flight tests of the PVOR combined with a four-loop VOR and with a Doppler VOR indicate an improvement in system accuracy of better than 5 to 1. The overall reduction in siting effects is slightly better than that obtained with a Doppler VOR. The multilobe principle provides a potential 13-fold improvement in instrumentation and monitoring accuracy. The system described is a feasibility model. It is recommended that further effort be expended on an engineering model of a complete system, including monitoring and calibration equipment. (Author)

System feasibility checks, prior to NAFEC tests, on the Guide Light System show that it has high resolution and a reasonably good range and, depending on the results of accuracy tests, appears to be a promising technique for flight checking the accuracy of ILS installations. On a bright sunny day, the Guide Light System operating range was found to be about 3-1/2 nm; on a clear night, the range was about 5-1/2 nm. Ground tests showed that the course shift as a function of range was negligible. The Guide Light System that was designed and constructed consists of a ground station and an airborne flight-check receiver. At the ground station, the light from a 1-kilowatt tungsten-filament source is split into two light bands (infrared and visible) and modulated by a rotating drum. The flight-check aircraft receiver demodulates the light beams and, by measuring the phase angle between the demodulated audio signals, determines the in-space angular location of the aircraft. Angular information is contained in a 0.6-degree-wide beam symmetrically spaced about the center-line., Available copy will not permit fully legible reproduction. Reproduction will be made if requested by users of DDC. Copy is available for public sale.

This report contains an introduction to general navigational principles as applied to the use of doppler and inertial systems. This is followed by a description of both systems concerning methods of operation (such as steering), accuracy, etc. In-flight errors must be checked by some external ground-based navigation aids and this is discussed in some detail. A simplified procedure is given using VORTAC. After a description of airline flight planning, the impact of self-contained navigation techniques on the air-traffic-control system is discussed relative to en-route flying and the terminal area. It is concluded that doppler and inertial can be used successfully in domestic operations and that, subject to certain procedures, every encouragement should be given to all operators (including general aviation) to use doppler, and later inertial, in the domestic airspace. (Author)

This report describes the research activity on InSb varactors and the development of a cryogenically cooled, low noise, broadband parametric amplifier at X-band. Detailed measurements and evaluation of InSb and GaAs varactors have been made to determine their relative merits. Due to an anomalous current effect observed in InSb varactors, the final amplifier was delivered with a GaAs varactor. The amplifier had a noise temperature of 70 K, at 500 Mc bandwidth, and a mean gain of 16 db, when cooled to 77 K. (Author)

This report describes the results of a program aimed at demonstrating the feasibility of operating an advanced 2200-Mc traveling-wave maser amplifier with a closed-cycle refrigerator. The program proved the feasibility of such a system and tests indicate that the system is applicable to UHF telemetry stations. (Author)

The object of the research conducted under this contract is to determine whether techniques exist for raising the efficiency of electrically small and compact antennas used on aircraft, vehicle, and manpack communications equipment. A literature and patent search, and a state-ofthe-art review revealed the present status of small antenna technology, and indicated the directions on which further progress can be anticipated. Classical techniques of capacitive and inductive loading, of folding and arraying, and of ground decoupling, will receive further refinement. (Author)

Two service test models of the Antenna Coupler CU-613(XW-2)/GR, designed to prevent intermodulation of an associated 25-kw transmitter, met all electrical and environmental test requirements. The antenna couplers, tunable from 225 to 400 mc, provide a minimum rejection of 47 db to signals ! 5 mc from the resonant frequency with a maximum insertion loss of 0.63 db. The antenna couplers were tested to the environmental requirements of military specifications. Environmental conditions of extreme temperature, humidity, salt spray, shock, and vibration produced no degradation in the performance of the antenna couplers. (Author)

A miniature of solid-state comb-line switch has been developed which comes close to meeting all of the initial design goals. The switch, designed to operate in a circulator duplexer configuration, provides a 2-db bandwidth of 1000 MHz with greater than 10-db isolation. Over 90% of this band, the isolation is greater than 15 db. In the circulator configuration, the overall isolation would be well above the specified 20-db level. Diode power measurements indicate that both the specified peak and average power levels can be safely handled. Waveguide switch structures were considered and were found to be unable to provide sufficient bandwidth. (Author)

The objective of the study was to determine the feasibility of new technical concepts inherent in the design of F sub 1, F sub 1 repeaters. This technical report covers two novel versions of small F sub 1, F sub 1 radio repeaters designed for use with FM tactical transceivers. Both developmental models are linear, single frequency repeaters (F sub 1, F sub 1), one is high gain (50 db); the other wide-band (500 kHz). The design of these repeaters utilizes the concepts of hybrid isolation and precise antenna matching. The results indicate that true F sub 1, F sub 1 radio repeaters are feasible. Included are detailed discussions of: F sub 1, F sub 1 repeater concept; antenna matching and broadbanding techniques; hybrid isolation; amplifier and filter development; tests and evaluation; miniaturization; future trends and goals., Sponsored in part by the DARPA.

This final report represents a two-year effort on the development of a multielement tunable superconductive preselector, and the investigation into the RF properties of high-temperature superconductors, notably niobium-stannide (Nb3Sn). The program resulted in the following major accomplishments: (1) Developed the first multielement superconductive band-pass filter. (2) Demonstrated the feasibility of a high-temperature superconducting high-Q RF rilter (unloaded Q as high as 4.2 million was measured using niobium stannide superconductor). (3) Successfully demonstrated a complete high-temperature niobium stannide superconducting resonator cooled by a small compact closed-cycle refrigerator. (4) Showed that lucalox (aluminum oxide) dielectric combines, at cryogenic temperatures, the properties of very low dielectric loss and high thermal conductivity, needed for closed-cycle cooling. The report also presents the theory operation, electrical performance and the physical configurations of the filter models developed. (Author)

The objective of the program was to develop new components for extending the fundamental frequency operating range of the AN/GPM-59 In-Guide Spectrum Analyzer between 1.12 GHz and 11 GHz, with capabilities of detecting and measuring spurious signals up to 22 GHz. Through most of the measurement range, continuous spectrum measurements can be performed on any standard waveguide system with a decoupling of any combination of coupler and commutator assembly of less than 40 db (for the most part, typically 30 db). Components developed include: (1) two high sensitivity, non directional probe couplers; (2) a low frequency stripline commutator; (3) a high frequency waveguide commutator; (4) five pairs of nonlinear tapers; and (5) a synchronization power supply. The two couplers, fabricated in WR-975 and WR-284 waveguide, can be used with systems in which the fundamental frequency ranges from 1.12 GHz to 2.6 GHz and from 3.95 GHz to 11 GHz, respectively. The couplers and tapers are designed for use in standard radar systems which may be pressurized up to 30 psi and operated at peak power levels up to 6 megawatts. Limited testing in operational radars showed that the components did not induce arcing. (Author)

The purpose of the program was to determine and develop techniques for evaluating the performance of wide-band radar systems. A repeater technique was chosen as being most suitable and a wide-band radar evaluator was breadboarded employing this technique. The breadboard model was tested in the laboratory employing a wide-band radar system exciter and signal processor. The results obtained confirmed the feasibility and suitability of this technique. Sufficient knowledge was gained to generate an evaluator design for a particular wide-band radar system, the Floyd Site Radar. (Author)

This report describes an investigation of circuit techniques to minimize spurious responses in transistor amplifiers. An investigation was conducted of both bipolar transistor amplifiers and field-effect transistor amplifiers. For bipolar transistor amplifiers, equations were derived which predict harmonic generation, intermodulation, and cross-modulation. These equations include dependence upon circuit configuration (common emitter, common base, and common collector), load resistance, source resistance, frequency, feedback, cascading, and bias current and voltage. Extensive measurements verify the validity of the equations with good correlation under nearly all conditions for several transistors (2N2857, 2N3137, 2N3553, 2N3995, TIXS40). For field-effect transistor (FET) amplifiers, the nonlinear characteristics were determined by measurements of several FET's (K1201, K1003, 2N3823, TIXS35). It was shown that a simple graphical analysis can be used to determine the bias conditions for which the nonlinear effects are minimized. The measurements indicate that the FET is probably better than the bipolar transistor for equal transistor dissipation. Since present FET's do not have the dissipation capabilities of bipolar transistors, they are likely to be out-performed by bipolar transistors with higher dissipation capabilities. (Author)