Engineering topics

Zimmerman, Martin L.

Publications and source records attributed to Zimmerman, Martin L..

3 records

NASA NTRS1995

FDTD-ANT User Manual

This manual explains the theory and operation of the finite-difference time domain code FDTD-ANT developed by Analex Corporation at the NASA Lewis Research Center in Cleveland, Ohio. This code can be used for solving electromagnetic problems that are electrically small or medium (on the order of 1 to 50 cubic wavelengths). Calculated parameters include transmission line impedance, relative effective permittivity, antenna input impedance, and far-field patterns in both the time and frequency domains. The maximum problem size may be adjusted according to the computer used. This code has been run on the DEC VAX and 486 PC's and on workstations such as the Sun Sparc and the IBM RS/6000.

Zimmerman, Martin L.↗

NASA NTRS1991

Designs for the ATDRSS tri-band reflector antenna

Two approaches to design a tri-band reflector antenna for the Advanced TDRSS are examined. Two reflector antenna configurations utilizing frequency selective surfaces for operation in three frequency bands, S, Ku, and Ka, are proposed. Far-field patterns and the antenna feed losses were computed for each configuration. An offset-fed single reflector antenna configuration was adapted for conceptual spacecraft design. CADAM drawings were completed and a 1/13th scale model of the spacecraft was constructed.

Lee, Shung-Wu↗

NASA NTRS1990

Reflector spillover loss of an open-ended rectangular and circular waveguide feed

An important and frequently used parameter in the design of a feed for a reflector antenna is the spillover loss. A set of spillover curves is presented for several common feeds, namely circular waveguides with TE11 or TE21 excitations, rectangular guides for the monopulse application, etc. The difference between two common methods of normalizing the feed input power is also discussed.

Lee, Shung WU↗