Strategies for corporate governance in engineering corporations

Although corporate governance plays a crucial role in shaping the vision, image and reputation of a corporation, this subject has been largely ignored in the prevailing engineering and technology management literature. In the wake of scandals like Enron and WorldCom, the call for effective corporate governance echoes across the boardrooms of many corporations. It is the intent of this paper to close the gap between the myth and the reality of US corporate governance effectiveness in engineering companies and to suggest some improvement strategies regarding the modus operandi and optimum structure of this entity. This study would benefit the board of directors of engineering companies that are already in existence or those that are in the process of being formed. It relies on survey results with individuals who, by virtue of their significant experience in the boardroom of engineering corporations, can offer unique insight and provide valuable data to the topic of corporate governance.     

An X- to ku-band 3-bit digital MEMS varactor

A 3-bit digital microelectromechanical system (MEMS) varactor bank is demonstrated on a low-cost glass substrate. It is composed of three discrete-position varactors, each of them achieving a capacitance ratio close to 3:1. The total capacitance of the varactor bank is tunable from 146 fF to 430 fF in eight states and is suitable for X- or Ku-band operation. The design can be easily scaled to Ka-band frequencies.     

A 2-bit miniature X-band MEMS phase shifter

The design and performance of a compact low-loss X-band true-time-delay (TTD) MEMS phase shifter fabricated on 8-mil GaAs substrate is described. A semi-lumped approach using microstrip transmission lines and metal-insulator-metal (MIM) capacitors is employed for the delay lines in order to both reduce circuit size as well as avoid the high insertion loss found in typical miniaturized designs. The 2-bit phase shifter achieved an average insertion loss of -0.70 dB at 9.45 GHz, and an associated phase accuracy of /spl plusmn/1.3/spl deg/. It occupies an area of only 5 mm/sup 2/, which is 44% the area of the smallest known X-band MEMS phase shifter . The phase shifter operates over 6-14 GHz with a return loss of better than -14 dB.     

A millimetre-wave bandpass filter-lens array

A filter-lens array (FLA) is a planar array of bandpass integrated antenna-filter-antenna (AFA) elements which are stagger-tuned in the vicinity of a centre frequency, so as to provide the phase shift required for transforming spherical and planar wavefronts. Due to the filtering response of the AFA elements, FLA presents a bandpass gain and can act as a combination of a conventional lensarray and a filter. An FLA structure is demonstrated with f/D=1.25 and 8.2% bandwidth at 35 GHz. This FLA is composed of 137 AFA elements and fabricated on two three-inch glass wafers (epsi_r=4.45). A gain of 25.6 dBi and a total efficiency of 45% have been measured at 35 GHz. The Ka-band FLA shows a low-loss scanning performance for up to at least plusmn30deg in the H-plane and plusmn20deg in the E-plane     

Stress-Induced Changes to the Triple-Point Phase Boundary of the Niobium-Deuterium System

Abtract The effects of mechanical stress, due to cold rolling, on the triple-point phase equilibrium in the niobium-deuterium system have been investigated using differential scanning calorimetry. Both unstressed and stressed foil samples of niobium-deuterium were analyzed over the temperature range 323 to 398 K. Over this temperature range, niobium-deuterium undergoes several phase changes (depending on the composition of the niobium-deuterium specimen). Differential scanning calorimetry allowed determination of temperature, energy, and compositional characteristics of these phase changes. It has been found that mechanical deformation has a significant effect on all of these characteristics.     

A planar wideband 80-200 GHz subharmonic receiver

A wideband planar subharmonic mixer has been designed for millimeter-wave operation. The receiver consists of a back-to-back Schottky-diode pair integrated at the base of a wideband log-periodic antenna and placed on a silicon lens. The wideband planar receiver results in state-of-the art-performance at 90 GHz (and 182 GHz) with a double-sideband conversion loss and noise temperature of 6.7 dB (and 8.5 dB) and 1080 K (and 1820 K), respectively. These results are about 3 dB higher than the results for best tuned waveguide subharmonic mixers using planar diodes. The design is well suited for higher frequencies (up to 1 THz) and for the inclusion of biased back-to-back planar diodes to ease the LO power requirements. The planar subharmonic approach results in an inexpensive wideband receiver, and the design can be easily extended to receiver arrays     

Monolithic millimeter-wave two-dimensional horn imaging arrays

A monolithic two-dimensional horn imaging array has been fabricated for millimeter wavelengths. In this configuration, a dipole is suspended in an etched pyramidal cavity on a 1-μm silicon-oxynitride membrane. This approach leaves room for low-frequency connections and processing electronics. The theoretical pattern is calculated by approximating the horn structure by a cascade of rectangular-waveguide sections. The boundary conditions are matched at each of the waveguide sections and at the aperture of the horn. Patterns at 93 and 242 GHz agree well with theory. Horn aperture efficiencies of 44±4%, including mismatch and resistive losses, have been measured. A detailed breakdown of the losses is presented. The coupling efficiency to various f-number imaging systems is investigated, and a coupling efficiency of 24% for an f0.7 imaging system (including spillover, taper, mismatch and resistive losses) has been measured. Possible application areas include imaging arrays for remote sensing, plasma diagnostics, radiometry and superconducting tunnel-junction receivers for radio astronomy     

Tapered slotline antennas at 802 GHz

Broken linearly tapered endfire slotline antennas (BLTSAs) were fabricated on 1.7-μm thin SiO₂-Si₃N₄ dielectric membranes. Antenna patterns in the E-, H-, and D-planes were measured at 802 GHz. The -10 dB beamwidths were found to be approximately 40° in all planes, with side lobe levels below -11 dB (-19 dB in the E-plane). The cross-polarized peaks in the D-plane were 8 dB below the copolarized peak. A theoretical model for calculating the E- and H-plane patterns of tapered slotline antenna 10 is extended to include the co- and cross-polarized D-planes. Measured and calculated patterns show good agreement     

High-gain step-profiled integrated diagonal horn-antennas

Dipole-excited integrated horn antennas are limited by their large flare angle of 70°, which is inherent in the anisotropic etching process of 〈100〉 silicon wafers. The large flare angles does not allow for integrated horns with gain higher than 13 dB and for 10-dB beamwidths less than 90°. A step-profiled horn is proposed which reduces the effective flare angle of the horn and allows gains in the region 17 dB to 20 dB to be achieved. The symmetry of the horn's radiation pattern is enhanced by positioning the exciting dipole along the diagonal of the horn cavity. A specific design example is shown with a gain of 18.4 dB and a 10-dB beamwidth of 37° in the E, H and 45° planes. The coupling efficiency of this horn to a Gaussian beam is calculated to be 83%. An equivalent smooth envelope-horn was built at 12.1 GHz and the measured patterns agree well with theory. The integrated step-profiled horn is well suited for millimeter-wave and terahertz focal plane imaging arrays requiring a large number of elements