Showing papers by "Daniel J. Hoppe published in 2008"

A High-Power $Ka$ -Band (31–36 GHz) Solid-State Amplifier Based on Low-Loss Corporate Waveguide Combining

Abstract: A method of using low-loss waveguide septum combiners is developed into a high-power -band (31-36 GHz) amplifier producing 50 W at 33 GHz (Ka-band) using 32 low-power (>2 W) solid-state amplifier modules. By using low-loss waveguide combining and a packaged monolithic microwave integrated circuit with a low-loss microstrip-to-waveguide launcher, the output loss is minimized, allowing for the overall power-combining efficiency to remain high, 80% (average insertion loss of combiner < 0.7 dB and average insertion loss of launcher <0.3 dB) over 31-36 GHz. In the past, lower power-combining efficiencies have limited the number of modules that can be combined at -band, and hence, have limited the power output. The approach demonstrated in this paper, with high power-combining efficiency, allows a very large number (32) of solid-state amplifier modules to be combined to produce high powers. Greater than 50 W was demonstrated with low power modules, but even higher powers 120 W are possible. The current approach is based on corporate combining, using low-loss waveguide septum combiners that provide isolation, maintaining the true graceful degradation of a modular solid-state amplifier system.

Focal Plane Array Receiver for Deep-Space Communication

Abstract: Typical ground antennas intended for use in space communication require large apertures operating at high frequencies. The challenges involved with these applications include achieving the required antenna performance in terms of antenna aperture efficiency and pointing accuracy. The utilization of a focal plane array in place of a standard single mode feed minimizes these problems. This paper discusses the key elements required to implement a focal plane array on a large high frequency antenna. It is shown that adaptive "least mean-square" (LMS) algorithms applied to the output of the array elements obtain the optimum combining weights in realtime, even in the presence of dynamic interference such as nearby spacecraft in array's field-of-view, or planetary radiation. This adaptive optimization capability maximizes the combined output SNR in real time, ensuring maximum data throughput in the communications link when operating in the presence of receiver noise and external interference generally present during planetary encounters.

Gaseous dielectric high voltage insulation for space applications

Abstract: This paper describes a miniature high voltage power supply for space use that is comparable to a TWTA EPC. The supply uses a gaseous mixture of SF6 and N2 for bulk high voltage insulation rather than a solid dielectric (i.e., potting). Experimental breakdown data show good agreement with ionization theory after accounting for geometrical effects typical of real power supplies. In the proper application, a gaseous dielectric is advantageous compared to potting for minimizing mass and volume. Gaseous dielectrics also offer certain manufacturing advantages such as guaranteed freedom from voids and ease of rework.