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The Effect of Antenna Covers On GPS Baseline Solutions

Antenna Covers Tested

+ The Ashtech conical cover is shown in figure 1. The cover is conically shaped and is mounted on to the antenna using a set of plastic (nonconducting) screws. There is no metal or conducting surface that is part of the antenna cover.

Figure 1: Ashtech conical cover mounted on their Dorne Margolin choke ring antenna.

+ The Trimble conical cover is shown in figure 2. The cover mounts on to a metal plate under the antenna. Figure 2 shows the antenna cover mounted over a Trimble Dorne Margolin choke ring antenna, and the mounting plate under the choke ring antenna.

Figure 2: The left picture shows a Trimble conical cover with metal mounting plate, using a Trimble Dorne Margolin choke ring antenna. The picture on the right is of the Trimble Dorne Margolin choke ring antenna and the mounting plate for the cover.

+ The one-eighth inch acrylic spherical dome is shown in figure 3. The dome is mounted so that the phase center sits in the center of the dome in the left picture. In the right picture, the phase center is not centered in the middle of the antenna cover. The plexiglass plate under the antenna in the picture on the right was not part of the cover, and did not effect the solutions.

Figure 3: Prototype one-eighth inch conical covers from UNAVCO. The left picture is of the UNAVCO spherical dome mounted so that the mean phase center is in the center of the spherical dome. The picture on the right has the spherical dome mounted slightly lower on the antenna, so that the phase center is no longer in the center of the dome

+ The one-quarter inch acrylic spherical dome is shown in figure 4. The dome is mounted onto the plexiglass plate under the antenna. The phase center of the antenna is not centered in the middle of the spherical cover.

Figure 4: A prototype one-quarter inch spherical cover mounted on a plexiglass plate. This spherical dome is mounted on the plate such that the phase center is not located at the center of the dome.

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Last modified Thursday, 17-Nov-2005 03:58:00 UTC

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