[1] We present new polarimetric radar data for the surface of the north pole of the Moon acquired with the Mini-SAR experiment onboard India's Chandrayaan-1 spacecraft. Between mid-February and mid-April, 2009, Mini-SAR mapped more than 95% of the areas polewards of 80°latitude at a resolution of 150 meters. The north polar region displays backscatter properties typical for the Moon, with circular polarization ratio (CPR) values in the range of 0.1-0.3, increasing to over 1.0 for young primary impact craters. These higher CPR values likely reflect surface roughness associated with these fresh features. In contrast, some craters in this region show elevated CPR in their interiors, but not exterior to their rims. Almost all of these features are in permanent sun shadow and correlate with proposed locations of polar ice modeled on the basis of Lunar Prospector neutron data. These relations are consistent with deposits of water ice in these craters.

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Analyses of heat spreading, temperature distribution, and resultant cooling effects in a monolithically Peltier-cooled laser (MPCL) structure are presented. The analyses were obtained by using Laplace's equation and were made under steady-state conditions, assuming constant thermal c.ondu.ctivity: In this MPCL structure a metal surface layer surrounds a heat-generating p-n laser JunctIon. It IS shown that by depositing relatively thick metallic cooling plates a 15% temperature reduction and 25% thermal spreading can be achieved. This heat spreading due to the passive cooling is added to the cooling obtained when the Peltier cooler is operated. Experimental measurements of the effect of Peltier cooling reveal a 6.8 °C reduction in junction temperature corresponding to a wavelength shift of as much as 20 A.

Results on a via-hole interconnect that links a coplanar waveguide (CPW) on one side of a 100-mm thick GaAs substrate to a microstrip line on the opposite side are presented. The measured insertion loss of a pair of back-to-back connections is 0.3 dB between 26.5 and 40 GHz. A lumped-element equivalent circuit of this via-hole interconnect has been extrapolated to W-band and used to design amplifiers at 94 GHz.

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