A compact manufacturable 76-77-GHz radar module for commercial ACCapplications

The design and measured results of a single-substrate transceiver module suitable for 76-77-GHz pulsed-Doppler radar applications are presented. Emphasis on ease of manufacture and cost reduction of commercial millimeter-wave systems is employed throughout as a design parameter. The importance of using predictive modeling techniques in understanding the robustness of the circuit design is stressed. Manufacturing techniques that conform to standard high-volume assembly constraints have been used. The packaged transceiver module, including three waveguide ports and intermediate-frequency output, measures 20 mm×22 mm×8 mm. The circuit is implemented using discrete GaAs/AlGaAs pseudomorphic high electron mobility transistors (pHEMTs), GaAs Schottky diodes, and varactor diodes, as well as GaAs p-i-n and pHEMT monolithic microwave integrated circuits mounted on a low-cost 127-μm-thick glass substrate. A novel microstrip-to-waveguide transition is described to transform the planar microstrip signal into the waveguide launch. The module is integrated with a quasi-optical antenna. The measured performance of both the component parts and the complete radar transceiver module is described     

On resonance phototunneling and photoelectric properties ofpInSb-nCdTe heterojunction

Photoelectric properties and current-voltage characteristics of_pInSb-_nCdTe heterojunction have been studied as a function of_nCdTe layer thickness. Spectral dependence of photoconductivity has been found, as well as the junction field penetration domain in_nCdTe. Various mechanisms of charge separation are considered: resonance phototunneling mechanism, and absorption mechanism with further tunneling through the barrier, which explains the character of spectral dependence for the photoconductivity both beyond the maximum of spectral dependence and beyond edge of fundamental absorption for_pInSb. By the photoconductivity fall-off we have determined the concentration of impurity N_D, which stays in good agreement with the N_D value determined from measurements of field penetration depth. Possibilities of extending the photosensitivity to higher wavelengths range are discussed, by variation of impurities concentrations N_A and N_D, and by means of the external electrical field.     

Possibility of Self-Induced Transparency in Multi-Layer Semiconductor Heterostructure Placed in a Quantizing Magnetic Field

The possibility of self-induced transparency is discussed in a semiconductor structure with 3D-quantized electron spectrum. A model structure is proposed, for which a significant decrease of pulse duration and an increase of power is obtained.     

Clinical evaluation of Asaley

Asaley is an L-leucine derivative of sarcolysin which is more active against some rodent tumors. Studies in the USSR demonstrated activity in patients with ovarian and breast carcinoma, Hodgkin's disease, and multiple myeloma. This study in 73 evaluable patients indicated that an appropriate oral dose for patients with adequate bone marrow is 800 mg/M2/day X 4 days at 5-6 week intervals. The most common toxicities were myelosuppression, nausea, and vomiting. Antitumor activity was observed in 2 of 24 evaluable patients with melanoma, and stabilization of previously progressive disease was observed in patients with adenocarcinoma of the colon, multiple myeloma, lymphoma, breast carcinoma, and thyroid carcinoma. Responses were minimal and of short duration but most of the patients had received extensive prior therapy.     

Broad-band high-power amplifier using spatial power-combining technique

High power, broad bandwidth, high linearity, and low noise are among the most important features in amplifier design. The broad-band spatial power-combining technique addresses all these issues by combining the output power of a large quantity of microwave monolithic integrated circuit (MMIC) amplifiers in a broad-band coaxial waveguide environment, while maintaining good linearity and improving phase noise of the MMIC amplifiers. A coaxial waveguide was used as the host of the combining circuits for broader bandwidth and better uniformity by equally distributing the input power to each element. A new compact coaxial combiner with much smaller size is investigated. Broad-band slotline to microstrip-line transition is integrated for better compatibility with commercial MMIC amplifiers. Thermal simulations are performed and an improved thermal management scheme over previous designs is employed to improve the heat sinking in high-power application. A high-power amplifier using the compact combiner design is built and demonstrated to have a bandwidth from 6 to 17 GHz with 44-W maximum output power. Linearity measurement has shown a high third-order intercept point of 52 dBm. Analysis shows the amplifier has the ability to extend spurious-free dynamic range by N/sup 2/3/ times. The amplifier also has shown a residual phase floor close to -140 dBc at 10-kHz offset from the carrier with 5-6-dB reductions compared to a single MMIC amplifier it integrates.     

Optical characteristics of quantum-well heterostructures in saturation conditions

The resalts of theoretical investugation for spectral characterstics of gain, refraction index of QW heterostructures depending on quantum layer thickness the value of saturation field, as well as their field dependence are presented.