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DIGISONDE-4D
SYSTEM MANUAL
VERSION 1.2.11
SECTION 2 - INSTALLATION, SETTING UP AND FIELD VALIDATION 2-9
Receive Antenna Array Layout
2:28. The sounder installation uses a receive antenna array consisting of four antenna stations, three of which
form an equilateral triangle, the fourth station is located at its center. Figure 2-3 details array layout meas-
urements and antenna orientation. The location of each crossed-loop antenna station in each antenna field
shall be in accordance with the installation drawings.
2:29. Deviations from the standard antenna array configuration shown in Figure 2-3 are acceptable if the
available space for the antenna field does not accommodate the standard configuration. Deviations shall be
properly reflected in the station personalization files (see Paragraph 2:52, et seq.).
2:30. The orientation of the individual antennas is not critical as long as all four receive antennas are parallel
to each other within 1 degree. i.e., if one antenna has its legs NW, NE, SE, and SW, then the other antennas
must have their legs positioned exactly the same. Most commonly one loop is positioned magnetic North -
South, and the other loop is positioned magnetic East - West.
2:31. Orienting the antenna array with respect to the Geographic North simplifies configuration of the analy-
sis software. If orientation is done with respect to the ground level compass North, the configuration files
need to store deviation of the antenna array axis from the Geographic North at the time of installation to ac-
count for movement of the magnetic North Pole with time.
2:32. The vertical plane polarization and East-West (i.e., orientation of North-south loop planes) of all four
turnstile antennas must be within 1 of the datum line. All antenna preamplifier boxes must be oriented
identically on each receive antenna station. Orientation of the Antenna #3 / Antenna #2 side of the triangle
should be preferably Geographic North (see Figure 2-3).
2:33. Each receive antenna station comprises four crossed-loop active elements. Physical details of the an-
tenna station including its concrete footing are provided in Figure 2-2 showing a small concrete pad for
each antenna leg. There certainly are alternative ways of installing the antennas depending on local weather
and soil conditions. However the antenna legs are installed, the antennas should be restrained from being
blown around by wind or being inadvertently moved from position. The Polarization Switch (pre-amp)
mounted under the lower cross of the loops should be high enough to be out of any vegetation.
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