Monolithic mm-wave phase shifter using optically activated superconducting switches

A phase shifter is disclosed having a reference path and a delay path, light sources, and superconductive switches. Each of the superconductive switches is terminated in a virtual short circuit, which may be a radial stub. Switching between the reference path and delayed path is accomplished by illuminating the superconductive switches connected to the desired path, while not illuminating the superconductive switches connected to the other path

Examining Private Investment Heterogeneity: Evidence from a Dynamic Panel

domestic private investment, public investment, dynamic heterogeneity, endogeneity, Generalised Method of Moments

Government Solvency: Revisiting some EMU Countries

Corsetti and Roubini (1991) reported that the government finances of Greece, Ireland, Italy and the Netherlands (now all EMU countries) did not satisfy the intertemporal budget constraint (IBC). We re-examine this issue by utilizing a new empirical approach and extended data set. Structural shifts, an issue which Corsetti and Roubini were unable to address due to the lack of suitable econometric methods, are tackled. We find that: (i) multiple structural shifts, most of which correspond to important policy changes, did occur in the fiscal path of these countries; (ii) the effect of the majority of structural shifts has been to strengthen the evidence supporting IBC; and (iii) government finances of all four countries satisfy the IBC and this finding is robust to different time horizons. We also find a clear positive Maastricht effect on IBC for all countries.intertemporal budget constraints, strong and weak form sustainability, structural breaks

Optically interconnected phased arrays

Phased-array antennas are required for many future NASA missions. They will provide agile electronic beam forming for communications and tracking in the range of 1 to 100 GHz. Such phased arrays are expected to use several hundred GaAs monolithic integrated circuits (MMICs) as transmitting and receiving elements. However, the interconnections of these elements by conventional coaxial cables and waveguides add weight, reduce flexibility, and increase electrical interference. Alternative interconnections based on optical fibers, optical processing, and holography are under evaluation as possible solutions. In this paper, the current status of these techniques is described. Since high-frequency optical components such as photodetectors, lasers, and modulators are key elements in these interconnections, their performance and limitations are discussed

Optically controlled microwave devices and circuits: Emerging applications in space communications systems

Optical control of microwave devices and circuits by an optical fiber has the potential to simplify signal distribution networks in high frequency communications systems. The optical response of two terminal and three terminal (GaAs MESFET, HEMT, PBT) microwave devices are compared and several schemes for controlling such devices by modulated optical signals examined. Monolithic integration of optical and microwave functions on a single semiconductor substrate is considered to provide low power, low loss, and reliable digital and analog optical links for signal distribution

Optically controlled phased-array antenna technology for space communication systems

Using MMICs in phased-array applications above 20 GHz requires complex RF and control signal distribution systems. Conventional waveguide, coaxial cable, and microstrip methods are undesirable due to their high weight, high loss, limited mechanical flexibility and large volume. An attractive alternative to these transmission media, for RF and control signal distribution in MMIC phased-array antennas, is optical fiber. Presented are potential system architectures and their associated characteristics. The status of high frequency opto-electronic components needed to realize the potential system architectures is also discussed. It is concluded that an optical fiber network will reduce weight and complexity, and increase reliability and performance, but may require higher power

Financial Restraints in the South Korean Miracle

We provide novel empirical evidence on the effects of financial restraints on South Korean financial development. The evidence is linked to a simple model of the Korean banking system that encapsulates its cartelised nature, which predicts a positive association between financial development and (i) the degree of state control over the banking system, (ii) mild repression of lending rates. The model also predicts that in the presence of lending rate controls, increases in the level of the administered deposit rate are unlikely to influence financial deepening. We test the model empirically by constructing individual and summary measures of financial restraints. Our empirical findings are consistent with our theoretical predictions but contrast sharply with the predictions of earlier literature that postulates that interest rate ceilings and other financial restraints constitute sources of ‘financial repression’.Financial deepening; financial restraints