Showing papers on "Extremely high frequency published in 1994"

Active and nonlinear wave propagation devices in ultrafast electronics and optoelectronics

Abstract: We describe active and nonlinear wave propagation devices for generation and detection of (sub)millimeter wave and (sub)picosecond signals. Shock-wave nonlinear transmission lines (NLTL's) generate /spl sim/4-V step functions with less than 0.7-ps fall times. NLTL-gated sampling circuits for signal measurement have attained over 700-GHz bandwidth. Soliton propagation on NLTL's is used for picosecond impulse generation and broadband millimeter-wave frequency multiplication. Picosecond pulses can also be generated on traveling-wave structures loaded by resonant tunneling diodes. Applications include integration of photodetectors with sampling circuits for picosecond optical waveform measurements and instrumentation for millimeter-wave waveform and network (circuit) measurements both on-wafer and in free space. General properties of linear and nonlinear distributed devices and circuits are reviewed, including gain-bandwidth limits, dispersive and nondispersive propagation, shock-wave formation, and soliton propagation. >

Micromachined millimeter‐wave photonic band‐gap crystals

Abstract: We have developed a new technique for fabricating three‐dimensional photonic band‐gap crystals. Our method utilizes an orderly stacking of micromachined (110) silicon wafers to build the periodic structure. A structure with a full three‐dimensional photonic band gap centered near 100 GHz was measured, with experimental results in good agreement with theoretical predictions. This basic approach described should be extendable to build structures with photonic band‐gap frequencies ranging from 30 GHz to 3 THz.

Optical transmission of narrow-band millimeter-wave signals by resonant modulation of monolithic semiconductor lasers

Abstract: We demonstrate the use of monolithic semiconductor lasers as efficient narrow-band (20-300 MHz) millimeter-wave optical transmitters at a cavity round-trip resonant frequency of 45 GHz. The modulation efficiency within the passband is >10 dB above that of a conventional laser diode at frequencies below relaxation oscillation. At an input RF drive power of 10 dBm, a carrier-to-noise ratio of 90 dB (1 Hz) is achieved. We also present a system demonstration of this technique in which 50 Mb/s digital data is transmitted at a 45 GHz subcarrier over optical fiber. This is the highest subcarrier frequency transmission reported to date. >

A collision avoidance radar using six-port phase/frequency discriminator (SPFD)

Abstract: A novel technique is proposed for collision avoidance radar used in automobiles, in which a new six-port microwave/millimeter wave digital phase/frequency discriminator (SPFD) is used to measure Doppler frequency shifts. Both relative speed and moving direction of the target are readily obtained. Ranging is implemented by the measurement of phase difference at two adjacent frequencies. Preliminary experimental simulation proves the validity of the proposed alternative approach. >

Double‐etch geometry for millimeter‐wave photonic band‐gap crystals

Abstract: We have designed and developed a new double‐etch technique for fabricating three‐dimensional millimeter‐wave photonic band‐gap crystals. This technique doubles the band‐gap frequency obtainable from silicon wafers. By introducing overetching, the double‐etch geometry allows one‐way tuning of the midgap frequency. We have experimentally demonstrated this property by fabricating and testing structures with different overetch ratios. Terahertz spectroscopy techniques were used to measure photonic band‐gap crystals with midgap frequencies ranging from 340 to 375 GHz.

Millimeter wave narrowband optical fiber links using external cavity semiconductor lasers

Abstract: We present the theoretical analysis and the experimental implementation of a narrowband millimeter wave optical fiber communication system using an external cavity semiconductor laser. We derive analytic expressions and present experimental data for the modulation response, relative intensity noise, carrier-to-noise ratio, and harmonic distortion for a semiconductor laser in an external cavity operating as a transmitter in the millimeter wave frequency range. We present a system implementation of this capable of transmitting 40-Mbt/s digital data at a 35-GHz subcarrier frequency with bit-error rates below 10/sup /spl minus/9/ over a 6.3-km-long optical fiber link. >

Broad-band characterization of millimeter-wave log-periodic antennas by photoconductive sampling

Abstract: Results of photoconductive sampling measurements used to characterize millimeter-wave log-periodic antennas with continuous, simultaneous frequency coverage from 10 to 300 GHz are presented. Polarization properties are investigated employing wire-grid polarizers. This study reveals new information on structure resonances and antenna polarization. >

A broadband free-space millimeter-wave vector transmission measurement system

Abstract: We report both broadband monolithic transmitter and receiver IC's for MM-wave electromagnetic measurements. The IC's use a nonlinear transmission line (NLTL) and a sampling circuit as a picosecond pulse generator and detector. The pulses are radiated and received by planar monolithic bow-tie antennas, collimated with silicon substrate lenses and off-axis parabolic reflectors. Through Fourier transformation of the received pulse, accurate 30-250 GHz free space gain-frequency and phase-frequency measurements are demonstrated. Systems design considerations are discussed, and a variety of MM-wave broadband transmission measurements are demonstrated. >

Submillimeter wave generation and noise in InP diodes

Abstract: circuit are calculated using the MCP technique. It is shown that at the biases above the generation threshold the P, has a peak at the frequency f,, which corresponds to the highest generation frequency at the given R. The excess noise arises in the frequency region where the real part of diode impedance Re 2 has negative values. At the bias below the generation threshold (i.e., when Re Z is positive over entire frequency range) the P,(f) has the usual Lorenzian shape. The MCP simulation of Ps for 0.25~,um-length diode shows the Gaussian shape of the spectra at frequencies 517 and 622 GHz. The Ps broadening at higher frequencies is the result of interaction between the self-oscillations at frequency f,, and circuit-driven oscillations. I. INTRODUCTION Solid-state millimeter and submillimeter wave systems (MSWS) are very suitable for the communications and radar applications due to their broad bandwidths, high resolution, small size, light weight, resistance to jamming, and narrow beamwidth for pinpoint tracking. Their adverse weather operation is good compared with that of optical and infrared systems, which exhibit poor penetration characteristic in fog, haze, smoke, and dust. The above characteristics indicate that MSWS technology has major advantages over optical and infrared devices in seeker and detection systems. Millimeter wave systems (frequency range: 30-300 GHz) are relatively well developed. Submillimeter wave (300-3000 GHz) systems are still far from practical realization, due to a lack of high-frequency radiation sources. Therefore, an important task facing highspeed electronics is to increase the cutoff frequencies of * such major devices as diodes, transistors, etc.

Millimeter-wave imaging for nondestructive evaluation of materials

Abstract: A millimeter-wave imaging system has been developed in the W band (75--110 GHz) for nondestructive evaluation of low-loss materials. The system employs a focused beam to provide spatial resolution of about one wavelength. A plane-wave model is used to calculate the effective reflection (or transmission) coefficient of a multilayer geometry. Theoretical analysis is used to optimize the measurement frequency for higher image contrast and to interpret the experimental results. Both reflection and transmission images, based on backscattered and forward-scattered powers, were made with Kevlar/epoxy samples containing artificially introduced defects such as subsurface voids and disbonds. The results indicate that millimeter wave imaging has high potential for noncontact detection of defects in low-loss materials.

A 94 GHz MMIC tripler using anti-parallel diode arrays for idler separation

Abstract: A 31.33 to 94 GHz millimeter wave frequency tripler is described which employs large numbers of high cutoff frequency Schottky barrier diodes in compact series/parallel arrays. The high breakdown voltage, distributed nature of the diode array and all of the diodes being thermally in parallel result in high power handling capability. >

Tunable millimeter wave filter using ferromagnetic metal films

Abstract: The present invention discloses a frequency tunable filter which includes an electromagnetic (E-M) wave propagation line which includes a microstrip and a ground plane in the substrate for transmitting a sequence of E-M signals via the propagation line. The E-M wave propagation line includes a frequency tuning mechanism, i.e., the magnetic layer, which is capable of utilizing a ferromagnetic anti-resonance frequency response to the E-M signals transmitted via the propagation line for controlling and frequency tuning the E-M signal transmission. In one of the preferred embodiments, the E-M wave propagation line includes a microstrip forming on the top surface of a dielectric or semiconductor substrate for receiving and transmitting the E-M signals and a ground plane forming on the bottom surface of the semiconductor substrate. And, the frequency tuning mechanism includes a ferromagnetic layer formed in the substrate between the microstrip and the ground plane.

Terahertz bandwidth pulses for coherent time-domain spectroscopy

Abstract: Ultrashort pulses of electromagnetic radiation propagating through free space are used to perform coherent time-domain spectroscopy by probing the complex index of refraction of various materials, in particular thin films of high-critical- temperature superconductors and the microwave substrates that support them. The terahertz beam system utilizes Hertzian-dipole- like antennas consisting of a dc-biased photoconductive gap in a coplanar stripline as a transmitter, and an identical receiver with a photoconductive gap biased by the THz radiation. The transmitter is driven to produce the short radiation bursts by a 100-fs optical pulse from a Ti:sapphire self-mode-locked laser, while the receiver is synchronously gated by laser pulses split from the original beam. By performing measurements in the time domain and transforming data to the frequency domain, both the real and imaginary parts of the index of refraction of dielectrics and the conductivity of superconductors are determined over the entire range from approximately 200 GHz to several terahertz. This technique allows the direct broadband determination of these quantities in the mmw and sub-mmw regimes from the measurement of only a few time-domain waveforms and without the need for Kramers-Kronig analysis or complicated processing.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A new generation of SIS receivers for millimeter-wave radio astronomy

Abstract: A new generation of low-noise, dual-polarization heterodyne receivers covering all atmospheric windows between 68 and 300 GHz has been developed for the 12-m telescope on Kitt Peak, AZ, operated by the National Radio Astronomy Observatory (NRAO). A modular approach to the receiver construction has been used. Each receiver channel is constructed as a self-contained insert which is mounted in a dewar equipped with a closed-cycle 4 K refrigerator capable of cooling up to eight inserts, thereby enabling several frequency bands to be contained within one dewar. The telescope and receiver optics are so arranged that switching between frequency bands may be accomplished rapidly by rotating the optical elements placed in the signal path. Single-sideband noise temperatures ranging from 50 to 400 K are obtained across the frequency range. >

A new face‐centered‐cubic photonic crystal for microwave and millimeter‐wave applications

Abstract: Three-dimensional photonic crystals are fabricated that consist of a face-centered-cubic lattice of air atoms embedded in a synthetic dielectric matrix. The crystals are formed by stacking triangular arrays of cylindrical atoms in a close-packed arrangement. The fabrication technique is much simpler than previous methods and is well suited to producing photonic band gaps in the microwave and millimeter-wave regions. Microwave measurements provide strong evidence for a photonic band gap between approximately 17 and 18 GHz in a crystal having a volumetric air fraction of 60%. © 1994 John Wiley & Sons, Inc.

Detector for millimeter wave

Abstract: PURPOSE:To obtain an inexpensive detector of a millimeter wave whose manufacture is easy with excellent mass-productivity with respect to the structure of the detector for a millimeter wave including an antenna for a millimeter wave band. CONSTITUTION:A ground conductor film 2 and a dielectric film 3 are laminated on a 1st silicon-made semiconductor board 1, a plane antenna 4 and a feeding microstrip line 7 are formed on the dielectric film 3, and a 2nd gallium arsenide semiconductor board 5 on which a detection circuit is formed is mounted by a Phillips chip mount. Thus, an inexpensive silicon material is used for a part with a large area and expensive gallium arsenide is used for only an active element of a millimeter wave band to realize the detector inexpensively while keeping the high manufacture precision being a requirement for a millimeter wave band.

Performance of modulation-doped charge-coupled devices (MD-CCD's) in the microwave and millimeter-wave bands

Abstract: A two-phase, modulation-doped charge coupled device (MD-CCD) has been characterized by both phase shift and charge transfer efficiency (CTE) measurements from 1.25 MHz to 16.4 GHz. Both two-dimensional transient simulations and experimental evidence support the conclusion that the cutoff frequency for transport of discrete charge packets emulates the cutoff frequency of small signal HEMT devices in the short gate length regime. These simulations predict a CTE of almost 0.999 at 40 GHz for an In/sub 0.53/Ga/sub 0.47/As channel device. The device is fabricated using conventional MMIC processing techniques. In addition, measurement methods used for characterization of a prototype 5-stage delay line chip agree well with simulations using a new CCD SPICE model. >

Wide-band simulations and measurements of MM-wave indoor radio channels

Abstract: This paper provides the foundations for an image-based ray-tracing algorithm tailored to examine the propagation characteristics of millimeter wave indoor radio channels. In addition the implementation of a ray tracing algorithm is discussed. It is indicated that the ray tracing yields accurate results with respect to normalized received power and rms delay spread. In addition it is fast enough to support interactive radio system design on workstation or PC.

Integrated optically driven millimeter wave sources and receivers

Abstract: HBTs driven by mixing stabilized lasers and by mode locked semiconductor lasers have been used to make millimeter wave sources. New receiver configurations have been fabricated using edge coupled devices with integrated optical guides formed from InGaAsP quaternary layers and from polyimide. Further integration of our new polymer optical modulators now permits us to make modules suitable for applications in radar and communications. >

Electro-optic power control of a millimeter wave Gaussian beam

Abstract: The use of a molecular beam epitaxy (MBE) engineered III-V semiconductor to quasioptically modulate a millimeter wave Gaussian beam is presented. The effect is based on the generation of excess carrier densities under photonic excitation of the material. Low light power densities are required due to the high recombination lifetime achieved in the used material. A modulation depth of more than 15 dB and a dark insertion loss of less that 0.5 dB has been obtained at 100 GHz.© (1994) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

A compact high-performance dual-reflector millimeter-wave imaging antenna with a 20/spl times/20 degrees square field of view

Abstract: Several remote sensing applications require compact antennas capable of providing high-gain and narrow beamwidths over a wide frequency band and field of view. A high performance offset dual-reflector imaging antenna with a clear circular entrance aperture of 200 wavelengths in diameter, operating at 94 GHz, is presented. The antenna has concave ellipsoidal and hyperboloidal main- and sub-reflectors, respectively, with shape, location, and orientation determined by numerical optimization. It is capable of providing, across its entire 20/spl deg//spl times/20/spl deg/ square field of view, a practically constant radiation pattern with a half-power beamwidth of about 0.32/spl deg/, less than 1.4 dB of gain variation, and crosspolarized peak radiation more than 40 dB below the co-polarized peak value.

High-speed optical detectors for monolithic millimeter wave integrated circuits

Abstract: Metal-semiconductor-metal photo-diodes with interdigitated Schottky barrier fingers have been developed for applications in monolithic optical receiver circuits with the purpose of detecting millimeter wave modulation signals being transmitted via an optical carrier. The devices are planar and incorporated submicron finger spacings and a thin absorption region for speed with a buried stack of tuned Bragg reflectors for enhanced sensitivity at the carrier wavelength. These devices have been integrated with short-gate MODFET amplifiers to form the complete monolithic integrated optical receiver circuit. The circuits comprise of the active devices and coplanar waveguide matching/filter networks for optimal MMW performance. DC bias networks have also been integrated with the circuits.

Antenna-reflector combination operating in the Fresnel region at microwave and millimeter-wave bands

Abstract: A method for calculating antenna-reflector combination gain for rectangular reflectors operating in the Fresnel region is derived instead of an approximate method based on an equi-area circular reflector. The scope of microwave application of the method is discussed, and reflector-equipped microwave links in operation are examined using the new method. A field test result using 50-GHz radio equipment with four types of reflectors shows good agreements with the theoretical calculations. >

Frequency multiplied harmonic gyrotron-traveling-wave-tube amplifier

Abstract: Numerical simulations of a W‐band two‐stage tapered, frequency multiplied gyrotron‐ traveling‐wave‐tube amplifier are reported. Unlike conventional harmonic gyrodevices, a drive signal at the fundamental harmonic frequency is injected in the first stage for beam modulation, and amplified output radiation is extracted from the third harmonic cyclotron resonance interaction. Numerical results show that broadband millimeter wave radiation is obtained with an efficiency of 10%–15%, a gain of ∼30 dB, and an instantaneous bandwidth of ∼10% at a center frequency of 95 GHz for Δvz/vz=2%.

Modeling GAAs PIN Diodes for Microwave and Millimeter Wave Applications

Abstract: The need to keep system development cost low has given important emphasis to using well-defined solid-state component models in design and simulation of systems. This paper presents a new model for predicting the impedance of monolithic GaAs PIN diodes at microwave and millimeter wave frequencies.