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This paper presents an approach to detect people, or dismounts, using synthetic aperture radar (SAR). This approach is compared qualitatively with ground moving target indication (GMTI) radar and then quantitative results are presented using a P-band single phase center SAR. It is demonstrated that SAR provides an excellent methodology to detect dismounts., See also ADM002322. Presented at the IEEE International Radar Conference (9th), held in Arlington, VA on 10-14 May 2010. Sponsored in part by the Navy. The original document contains color images. Sponsored in part by AFOSR.

There is currently widespread interest in the development of radar sensors for the detection of surface and buried targets and the remote sensing of land, sea and ice surfaces. An important feature of electromagnetic radiation is its state of polarization and a wide range of classification algorithms and inversion techniques have recently been developed based on the transformation of polarization state by scattering objects. There are three primary ways in which multi-parameter radar measurements can be made: multi-frequency, single or multi-baseline interferometry and multi-polarization. While several airborne systems can now provide diversity over all three of these, it is the combination of polarimetry with interferometry at a single wavelength that forms the central focus of future challenges in developing new and original data processing. The main reason for this is the imminent launch of a series of advanced satellite radar systems such as PALSAR, an L-band SAR sensor on board the NASDA ALOS satellite and Radarsat II, a C-band polarimetric sensor. These are typical of a new generation of radars with the potential for providing data from various combinations of polarimetry and interferometry. This paper seeks to review recent progress in polarimetric and interferometric SAR data processing, covering advances and addressing the important topic of classification of polarimetric SAR data. Indeed, classification of Earth terrain components within a full polarimetric SAR image is one of the most important applications of Radar Polarimetry in Remote Sensing., Prepared in collaboration with the Remote Sensing Division, Naval Research Laboratory, Washington, DC. Presented at the Sensors and Electronics Technology Panel (SET) Lecture Series held in Warsaw, Poland on 21-22 March 2006. See also ADM001954. Published in RTO-EN-SET-081bis, Radar Polarimetry and Interferometry (La polarimetrie et l'interferometrie radar) Paper 7, p7-1 - 7-40, 2007. The original document contains color images.

This paper presents a novel concept for a low-mass 50m^2 deployable P-Band dual polarisation antenna, noting that P-Band observations can penetrate dense forests and possibly penetrate the earth to support searches for tunnels and caves. P-Band is important because existing optical or radar instruments cannot penetrate the forest canopy or the earth's surface in order to monitor suspicious activities. Existing space based Synthetic Aperture Radar (SAR) systems operate at a high frequency and the transmitted signals literally bounce off the canopy of these forests. Only with radars operating at P-Band or below can penetrate these forests. The antenna is designed to be used from a spacecraft in a low-Earth orbit. The antenna design has a monolithic array of feed and radiating patches bonded to a transversally curved structure consisting of two Kevlar sheets. The first sheet supports the array and the other sheet supports a ground plane. The two sheets are connected by a compliant Kevlar core that allows the whole structure to be folded elastically and to spring back without damage to its original shape on release. This structural concept has been given the acronym of FLATS (Folding Large Antenna Tape Spring). Test-pieces have been made to demonstrate both the RF and mechanical aspects of the design, particularly the RF performance before and after folding the structure. It is concluded that the proposed concept is the design with the highest potential for large low frequency antennas for low-cost missions. The difficulty facing the SAR system designer is that existing instruments at C-Band (5.3 GHz) already use antennas with areas greater than 10 m^2, and to maintain the same SAR performance, the antenna area varies inversely with frequency. Thus, at P-Band (0.435 GHz) an antenna of 50 to 100 m has to be launched and deployed in space. It is this packaging and structural problem and its unique solution that are the subject of this paper., Prepared in cooperation with the Department of Engineering, University of Cambridge, Cambridge, United Kingdom. Presented at the Specialists' Meeting organised by the Space Science and Technology Group, co-sponsored by the Romanian Space Agency and the US Air Force European Office of Aerospace Research and Development, at the National Military Circle, Bucharest, Romania, 6-7 Sep 2006 and published in the proceedings as paper 14. See ADM202419, Emerging and Future Technologies for Space-Based Operations Support to NATO Military Operations, RTO-MP-RTB-SPSM-001. The original document contains color images.

Density functional theory has been applied to a study of the electronic structure of the ideally-terminated, relaxed and H-saturated (0001) surfaces of b-Si3N4 and to that of the bulk material. For the bulk, the lattice constants and atom positions and the valence band density of states are all in good agreement with experimental results. A band gap of 6.7 eV is found which is in fair accord with the experimental value of 5.1?5.3 eV for H-free Si3N4. Using a two-dimensionally-periodic slab model, a p-bonding interaction is found between threefold-coordinated Si and twofold- coordinated N atoms in the surface plane leading to p and p* surface-state bands in the gap. A surface-state band derived from s-orbitals is also found in the gap between the upper and lower parts of the valence band. Relaxation results in displacements of surface and first-underlayer atoms and to a stronger p-bonding interaction which increases the p?p* gap. The relaxed surface shows no occupied surface states above the valence band maximum, in agreement with recent photoemission data for a thin Si3N4 film. The p* band, however, remains well below the conduction band minimum (but well above the Fermi level). Adsorbing H at all dangling-bond sites on the ideally-terminated surface and then relaxing the surface and first underlayer leads to smaller, but still finite, displacements in comparison to the clean relaxed surface. This surface is more stable, by about 3.67 eV per H, than the clean relaxed surface., Published in Surface Science, v579 p11-20, 2005.

The research funded the following projects - Metal-Insulator- Semiconductor Field-Effect-Transistor(MISFET), Ge/GaAs Heterojunction Bipolar Transistor (HBT), power HBT, and a theoretical investigation on Direct and Resonant Tunneling Diode (RTD). This project investigated the properties of MISFET type structures based on compound semiconductors. MISFET's have advantages over the aforementioned transistors in areas where high speed, simplicity of fabrication, uniformity of threshold voltages, low standby power, and high gate operational voltages are required. A major research goal is to investigate Ge/GaAs heterojunctions towards incorporating Ge in well established GaAs Heterojunction Bipolar Transistors (HBT's). This novel material combination will result in enhanced device performance. For HBT's, critical parameters affecting the device performance are base doping, base contact resistance, and band discontinuities at the emitter base junction. The semiconductor Ge has excellent potential to improve the performance of GaAs/A1GaAs HBT's. The third investigates the current handling capability of A1GaAs/GaAs HBT's. The idea is to use the HBT as a high- power and high-speed device. Multi-finger emitter and emitter ballasting resistor are used in the design of the HBT. The direct and resonant tunneling diode project used a k dot p band model to calculate the complex wave-vectors of the tunneling electrons in the calculation of the I-V characteristics of these types of diodes. Another important point in the calculation is the inclusion of semiconductor band-bending. (jhd)

This technical report presents the results of an analysis of the operational reliability for the EHF/UHF SATCOM System flight test program conducted by the Air Force Avionics Laboratory during the period of January 1976 to November 1977. The report was prepared as a case study covering a relevant literature review in such areas as reliability analysis models, methods to increase reliability, and SATCOM system reliability estimates. In addition, the study covered the data acquisition approach and data analysis results based on the reliability data obtained from the test program. Supporting appendixes covered such areas as the approach to estimating MTBF and the procedure for the calculation of the Confidence Interval as related to the MTBF.

The acronym METRRA represents 'Metal R-Radiating Radar'. The METRRA signature tests result from a third harmonic system, since the receive frequency is three times that of the transmit frequency. Of particular significance is METRRA's inherent ability to penetrate foliage. conventional radar systems provide returns from undesired targets such as trees, water, dense foliage, etc. , while the METRRA system does not. The METRRA process is responsive only to man made non linear junctions. Non linear junctions, when radiated by high power RF energy, convert the energy to harmonic frequencies and re-radiate.

A daily 24-hour monitor is maintained at Manila of total electron content and of scintillation at 136, 244, 257 and 1541 MHz signals from geostationary satellites. (Author)

As quantity and complexity of electronic systems on Navy ships increases, so does the probability of RF interference between systems, even those located on separate ships. This report briefly describes the coupling mechanisms possible between 200 MHz and 4000 MHz and supplies data in the form of graphs and describes a method whereby the magnitude of the interference can be quickly calculated for the various sea environments.

This note describes the design, construction, and performance of a 50 W UHF satellite transmitter which was built to demonstrate design and construction techniques that lead to easy replication of circuits in a manufacturing environment, without sacrifice in performance. High-efficiency performance is demonstrated over a 20 MHz band, centered at 260 MHz, with a fixed-tuned, single-ended design. (Author)

A radar experiment was conducted at Kwajalein Atoll, Marshall Islands to investigate the spatial relationship of 1-m equatorial spread-F irregularities to total electron content (TEC) depletion. A high-power radar was operated (1) in a backscatter scan mode to spatially map the distribution of 1-m irregularities, and (2) in a dual-frequency, satellite-track mode to obtain the longitudinal TEC variations. Using the radar data, we show that radar backscatter 'plumes' found in the disturbed, nighttime equatorial ionosphere are longitudinally coincident with TEC depletions. We suggest that the TEC depletions are probably due to the presence of plasma bubbles in the equatorial F layer. (Author)

This technical memorandum is presented in advance of formal reporting on the in-depth study of mechanisms and means for reducing intermodulation generation (IMG) in passive radio frequency (RF) hardware, presently under way at the Naval Research Laboratory (NRL). It is imperative that the communication community be again and quickly alerted to the harmonic and IMG interference danger of RF connectors and associated components which contain ferromagnetic materials (iron, nickel, cobalt, and their alloys). In a recent search for improved RF connector designs it became evident that the body structure of many of the newer type coaxial connectors and adapaters are being manufactured from stainless steel, type 303, a low permeability (2) ferromagnetic alloy. That such a material could be considered for fabricating RF connectors is difficult to understand because of the known non-linear effects of even small quantities of ferromagnetic contaminants in RF systems. To cut cost, nickel plating, another ferromagnetic material, is apparently also being widely substituted for previously used silver or gold plating of brass stock connectors. If satellite or other weak desired signal communication systems (utilizing multicarrier transmitters) are to succeed and/or survive, such interference generating materials must be eliminated in all transmission elements of the systems. To reverify the ferromagnetic threat and establish the magnitudes of interference, IMG tests of sample RF coaxial hardware were undertaken using the NRL IMG test facility.

A cross-slot antenna backed by a 33-in. square x 4.18-in. deep ridged cavity is described for operation in the 240 to 400 MHz band. The antenna was developed for a potential flight test evaluation using a satellite-to-aircraft communication link. Measured VSWR, radiation patterns and gain with the antenna mounted on a 9.5 ft x 9.5 ft cylindrically curved ground plane are shown. This curved ground plane simulates a section of the fuselage of a KC-135 aircraft., See also Rept. no. SAMSO-TR-75-241, ADA017298.

A unique approach is described for widening the bandwidth of a helical antenna with improved gain, pattern, and axial ratio characteristics. The antenna may be described as a non-uniform or quasi-taper helix, which consists of a combination of uniform and tapered helix sections. Measured patterns, gain, axial ratio, and VSWR for various helical antenna configurations are presented and compared. It is shown that a non-uniform, quasi-taper helix can provide an operating bandwidth twice that of a conventional uniform-diameter helix. (Author)

The objective of this handbook is to provide system designers with integrated circuit (IC) susceptibility information in terms of microwave signals. This is the final draft of the IC Handbook. The first and second drafts of the IC Handbook were reviewed by potential users, and their comments and suggestions have been incorporated where possible. The data in this handbook includes interference and damage susceptibility levels for digital and linear ICs. Actual test data is included when available. Modeling techniques are presented for the determination of device susceptibilities where no test data is available. The handbook explains an electromagnetic vulnerability (EMV) hardening approach for electronic systems. Coupling and shielding considerations are discussed. Susceptibility reduction techniques such as component screening, the use of lossy materials, and less susceptible circuit designs are also discussed. The handbook includes a description of the automated measurement system used to measure and analyze the IC susceptibility data. (Author), See also Rept. no. MDC-E1515, AD-A029 224 and Rept. no. MDC- E1669, AD-A043 777.

This patent discloses a P-band uniform loop antenna system simulating the small uniform in-phase current loop by using a number of smaller radiating elements that are connected in phase so that each current in each element is in phase. Thus, a small uniform loop radiation pattern is simulated, but the loop elements are arranged on a radius that is not small compared to a wavelength, and are located around a cylinder. (Author), Supersedes PAT-APPL-902 600-78.

The development and design of an electronically tuned, frequency tracked filter pair based on a combination of classifical microwave filter cavity designs and an electronically tuned resonator design technique is described. The filters, consisting of a 100 watt two pole filter and a 1000 watt single pole resonator, are intended to be placed at the input and output of a frequency hopping UHF power amplifier to reduce the broadband noise and spurious signal outputs of the resulting electronically tunable amplifier. The improvement in EMC (electromagnetic compatibility) performance allows the amplifier to be used in colocation environments with other equipment. The design of each of the electronically tuned filters is based on a previously developed method of tuning a high power resonator with PIN diode switched capacitors. The correlation of the design of both the combline input filter and the coaxial resonator output filter to the electronically tuned resonator with the susceptance slope parameters required is developed with mathematical models presented in the report. The primary result of this research is the development of an experimental model filter pair which demonstrates the feasibility of operating at power levels compatible with a 1000 watt power amplifier and tuning within the 350 to 400 MHz band in less than 60 microseconds.

It is anticipated that multipath propagation interference due to reflection from the sea will degrade APATS (ARIA Phased Array Telemetry System) reentry vehicle (RV) telemetry links. However, it is often feasible to reduce such interference by proper tailoring of the receiver position to the RV reentry parameters and telemetry characteristics. Theoretical analyses are presented which advocate specific ARIA flight constraints for several examples of P-band and S-band links in the context of nominal RV-aircraft (APATS) configurations. Issues such as APATs antenna gain, intersymbol interference, coherent and incoherent reflection from the sea, RV antenna gain, differential Doppler, RV-APATS geometry and RV trajectory are addressed in sufficient generally to permit application of basic multipath mitigation principles to a wide range of mission scenarios.

The new 35-GHz patrol radiometer at Sagamore Hill Solar Radio Observatory is described. The improved sensitivity of this system permits the detection of solar bursts down to about a 5-10 sfu level vs 50-100 sfu for the old system. This enhanced sensitivity will aid in the investigation of a wide range of topics pertaining to the physics of solar flares. These include but are not limited to spectral studies of large flare-bursts, correlations with hard x-ray data, and the detection of short cm-wavelength sharp-cutoff bursts. (Author)

Two broadband amplifier chains were developed for operation with a minimum output power of 10watts over the 225- to 400-megahertz band. Four stages were used in each chain, with each stage having 50-ohm input and output terminals. The stages in one amplifier chain operated in the common-base configuration; the other chain used common-emitter stages. Comparison of the rf performance of the two amplifier chains showed that common-base amplifiers provided a flatter output response, a higher power gain, and a lower input VSWR than common-emitter amplifiers. Infrared scanning performed on the output stages indicated that the common-base amplifier also had a lower junction spot temperature. In high-power common-base operation, extremely low base-lead inductance was necessary to prevent the amplifier from becoming regenerative. (Author)

The second and final phase of a terrain clutter study was completed at Naval Research Laboratory utilizing the Four-Frequency Radar System installed in a WV-2 (Super Constellation) aircraft, BuNo 128324. This system is capable of transmitting and receiving four frequencies (P,X,L, and C) consecutively with a choice of horizontal, vertical, and alternating polarizations. The returns are gated at a fixed range and analyzed in a digital computer. Absolute clutter measurements have been taken over several sites at angles of incidence from 5 degrees to 60 degrees. The parameter measured was the normalized radar cross section in terms of the median value of its probability distribution. Data were obtained for this parameter as a function of incident angle, transmitted and received polarization, and radar wavelength for a wide variety of terrain types such as desert, mountainous, urban, and water. A significant conclusion was that the wavelength dependence of the terrain clutter varies from n = 0 for urban terrain to n = 3/2 for marshes., See also Phase I rept. AD0653447.

Laboratory investigations have indicated that the phase shift amplifier has the capability of providing broadband low noise gain at frequencies as high as 1100 mc. The basic limitations of the phase shift amplifier are its intermodulation and cross-modulation characteristics which require it to be employed only in environments where there are no signals, within its band, having a power level greater than minus 40 dbm. For those applications where noise figure is not of primary concern, its power requirements and large physical size are also limitations when compared to transistor amplifiers. At higher frequencies, where transistor amplifiers are not available, the latter limitations become less significant., Rept. on Research and Development on Phase Shift Amplifiers in the 50-1100 MC band.

A tunnel-diode down converter designed and developed for conversion from X-band frequencies to UHF has proved that low noise figures are possible, when a forward bias voltage is chosen in the first region of the I-V characteristic of the tunnel diode so that the conductance Go is positive. When a sufficient local-oscillator voltage can drive the operating point into the negative-resistance region, the tunnel diode down converter exhibits a conversion gain and a noise figure 3 to 4 db lower than attainable with converters having common diodes. With a local oscillator frequency of 8.33 kMc and an IF of 30 mc, an average noise figure of 4.5 db was measured. For mismatched conditions of the in put admittance, a generator conductance Gg of 2 mhos was advantageously chosen in order to get a low noise factor and high gain. A microstrip line transformer was used to establish the high generator conductance. The measured noise figure of an improved second device, similar to the first one, was 3.0 db. The experimental devices are of attractively small size.

A final report of flame attenuation, as well as flame noise measurements made at AFETR on Titan IIIC, Test 8275/2250, April 28, 1967 is presented. Measurements were made at X-band(9100 MHz), C-band(5000MHz), S- band(2222 MHz), and P-band(220-250 MHz), frequencies at sites especially set up to yield a range of aspect angles, particularly at the low aspect angles of interest to AFWTR flights. Amplitude flame-noise measurements are reported for the first time for the Titan IIIC zero-stage. Power spectral density and probability distribution characteristics are presented. Also contained in this report are results of alkali-metal impurity measurements on the zero-stage, on the separation-rocket and the stage-I propellants; data on the effect of the exhaust flame on pulse transmission; and a plasma model of the zero-stage rocket exhaust from which predictions of rocket exhaust attenuation as a function of aspect angle and frequency can be made.

A study is presented of the integration of the digital data communications set AN/ASW-21 into the F8U-2N/2NE, A3D-2/2P/2Q, A4D-2/2N/5, A3J-1 and A2F-1 Aircraft. The AN/ASW-21 is a universal Data Link equipment which is designed for use with a wide variety of Navy aircraft. The AN/ASW-21 can be integrated into each aircraft with special mating equipments in the form of data processing, display, and autopilot coupling units, which will be provided by the aircraft manufacturers. The digital data communications set, AN/ASW-21, consists of a convertgital to-digital/analog, CV-1292/ASW-21, a computer, aircraft control, CP-671/ASW-21, and a control, data communications set, C-4085/ ASW-21.

The purpose of the project is to conduct a feasibility study of synchronous detection and direct signal conversion, and to fabricate an operating breadboard model. The ultimate objective is to incorporate microelectronic circuitry into a high-quality communications receiver for the 225- to 400-MHz band. A significant result is expected to be specifications for guiding the development of microelectronic circuits for receiver applications. (Author)

The work was oriented to define an operational telemetry system first, since the weight, size, power consumption, etc., affect the screening of candidate vehicles. The telemetry for R and D flights then can be configured to accommodate the additional R and D measurements by adding to the operational system.

Study and investigation was performed on the feasibility of a Solid State UHF Repeater/Amplifier. The goals set forth for the study program were an effective receiver sensitivity of one microvolt, an effective radiated power (ERP) of one watt, a dynamic range of 70 dB, retransmission within the same 50 KHz P-band channel as the received signal, operational capability over the entire 3500 channels of P-band, and the maximum weight of five points including antenna(s). Equipment limitations imposed by antennas, frequency errors, filters, integrated circuits, and frequency synthesizers were considered as a part of the study program. The study also included considerations of signal acquisition and tracking modulation compatibility, and protection of the receiver front end from desensitization by the retransmitted signal. The results of these several areas of study were used to design a configuration for the repeater amplifier that would satisfy the stated goals. (Author)

A circularly polarized radiating element with a gain of 10.5 plus or minus 1 dB over the 225- to 400-MHz band is described. The antenna consists of an open-sleeve dipole backed by a cavity 56 in. in diameter and 14.8 in. high. VSWR, axial ratio, pattern, and gain characteristics are presented. The measurements were made on a half-scale model, and all results are referred to the 450- to 800-MHz frequency band. (Author)

High reliability NPN transistors were designed and fabricated to operate at 50-watt output power levels in the frequency range from 225 to 400 MHz with power gains in excess of 5 dB. (1) A refractory metallization system consisting of Pt-Si, NiCr, W, Au was investigated and implemented. Devices were tested for electromigration induced failures and compared to those fabricated with an aluminum based system. (2) Geometrical design, material and processing were judiciously chosen to give the devices the required output power, gain and ruggedness under load mismatch conditions. The temperature distribution across the entire surface of the chip was measured under various adverse conditions to anticipate any reliability problems. Additionally, safe operational area testing was performed to check if secondary breakdown would occur at elevated levels of dc power dissipation. (Author)

The report documents the electrical and microelectronic design, battery development, demonstration tests, and environmental tests conducted on the engineering model of the Radio Set AN/PRC-63 (XN-1). It concludes in summary suggested design changes for improving reliability, maintainability and reduced size and weight. (Author), Available only for reference use at DDC field services. Copy is not available for public sale.