All of NASA’s Deep Space Network (DSN) 70-m reflectors were measured using a Leica TDM-5000 theodolite. The main-reflector surface was measured at five elevation angles so that a gravity deformation model could be derived that described the main-reflector distortions over the entire range of elevation angles. The article describes the measurement equipment and accuracy and the results derived f...

Antenna reflector losses play an important role in the calibration budget for a microwave radiometer. If the losses are small, they are difficult to measure by traditional means. However, they can be assessed directly by radiometric means using the sky brightness temperature as incident radiation. This paper describes how such measurements are carried out as well as a suitable experimental setu...

A low-threshold-current distributed reflector laser consisting of phase-shifted distributed feedback (DFB) grating and quantumwire distributed Bragg reflector (DBR) sections was realized. The device with a DFB length of 150μm, a DBR length of 240μm and a stripe width of 1.5μm achieved a threshold current as low as 1.2mA and a differential quantum efficiency of 13% from the front facet under RT-...

A high performance dye-doped cholesteric liquid crystal (CLC) laser is demonstrated by incorporating a passive CLC reflector to the active cell. The polarization-conserved CLC reflector effectively increases the distributed feedback cavity length which, in turn, results in a significant enhancement in lasing efficiency and a dramatic reduction in beam divergence. The lasing characteristics are ...

Based on the VMS survey of the compact array antenna CA02, the effects of gravity deformation were examined in AT 39.3/115. The dominant cause of gain loss and beam distortion was identified to be the deformation of the main reflector surface with elevation. This report examines whether active displacements in the sub-reflector and/or feed might compensate for the aperture wavefront errors. All...

Because of special structure, a dual reflector antenna has beam rotation capability in azimuth and elevation directions. In this structure, the antenna beam can be placed in any point in the space by mechanical movement of twist reflector which it is the most important ability of the antenna. Due to the antenna structure, if the polarization of incident wave is linear, it is expected that the p...

The Fermilab Booster is a rapid-cycling synchrotron which accelerates 84 bunches of protons from 401 MeV to 8 GeV for injection into the Fermilab Main Injector. The entire circumference, ie., all RF buckets, of the Booster is filled. At extraction, a kicker deflects the beam into the extraction channel. The kicker risetime is long enough so that several of the bunches do not receive the full ki...