| DESCRIPTION |
DSS-28 is one of two high-speed beam waveguide (HSB) antennas constructed by the Jet Propulsion Laboratory at the Goldstone Deep Space Communications Complex (GDSCC) for the U.S. Army; they were transferred to NASA in 1994, and DSS-28 was subsequently re-purposed for science experiments under the Goldstone Apple Valley Radio Telescope (GAVRT) project. DSS-28 may never have been used for deep space radio tracking or science. Station coordinates are approximate and have been inferred from those for DSS-27 which is nearby; the DSS-27 coordinates are listed in Table 5, module 301 (revision L), DSN Telecommunications Link Design Handbook (DSN document 810-005). The beam waveguide (BWG) design moves environmentally sensitive electronic equipment from a cone at the reflector focus into a pedestal. The radio signal is guided from the subreflector through a hole in the surface of the dish to the receiving equipment in the pedestal via a system of reflecting mirrors inside a large tube. The reverse path allows transmission. The BWG design reduces weight on the reflecting surface, provides insulation of electronics from environmental factors including dish movement, and simplifies maintenance. The HSB antenna differs from other BWG antennas in that the pedestal room is above ground level (rather than underground), the optics design is different, and the subreflector does not focus automatically for the purpose of maintaining gain as the elevation angle of the antenna changes. The HSB antenna has higher tracking rates than do other BWG antennas; thus, it is an appropriate antenna to use when tracking Earth-orbiting satellites. When operational DSS-28 may have transmitted 50-200 W at 2.1 GHz and received right- or left-circularly polarized signals
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