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If the noise originates in the near-field of the antenna, everything becomes unpredictable. This is a
good case for placing receiving antennas as far from noise sources (such as power lines) as possible.
Proximity to Transmitting Antennas
The ability of passive vertical element matching system components to survive high RF fields
depends on component ratings.
The
DX Engineering Active Matching Units with customer supplied vertical elements, or the
DXE-
ARAV3-8P
Receive Antenna Active Vertical with Relay active elements and your transmitting
antenna need only minimal physical separation to maintain safe power levels when the
DXE-
TVSU-1A
Time Variable Sequencer Unit is used. With 1500 watts output and a unity gain (0 dB)
antenna, the closest active element can be 1/10-wavelength from the transmitting antenna at the
lowest transmitting frequency. Doubling the protection distance quadruples safe power levels. See
Table 3
.
Band
Unity (0 dB) Gain 3 dB Gain (2x)
6 dB Gain (4x)
160m (1.8 MHz)
55 ft
110 ft
220 ft
80m (3.5 MHz)
28 ft
56 ft
112 ft
40m (7.0 MHz)
15 ft
30 ft
60 ft
Table 3 - Array Safety Distance Minimums at 1500 watts
Table 3
indicates minimum safe distances for the sequenced active array from transmitting antennas
with 0 dB, 3 dB and 6 dB gain (ERP) using a 1500 watt transmitter. Your actual system may vary
according to location and proximity to various objects. Your actual system may vary.
Safe distance
will vary depending on operating
frequency, antenna polarization and orientation, and
transmitting antenna pattern.
