text: Communications
  ANTENNA SITE
  6-137. Complete antenna systems, such as ground planes and dipoles, work better than fractional,
  wave-length, whip antennas. To further improve communications--
  • Locate antennas in clearings. Place them on the edge farthest from the distant station, and as
  high as possible.
  • Keep all cables and connectors--antenna, power, and telephone--off the ground to reduce
  damage from moisture, fungus, and insects.
  • If possible, clear vegetation from antenna sites. Foliage touching an antenna will ground its
  signal.
  • If vegetation cannot be removed, especially dense or wet vegetation, always
  horizontally polarize the antennas.
  HUMIDITY
  6-138. The high humidity of jungle environments condenses moisture on equipment. This encourages
  rust and fungus, complicating maintenance. Operators and maintenance personnel should check their TMs
  for special requirements but mainly they must--
  • Keep the equipment as dry as possible and in lighted areas to retard fungus growth.
  • Keep air vents clear to help keep equipment cool and dry.
  • Keep connectors, cables, and bare metal parts as free of fungus as possible. After repairs or
  damage, paint all surfaces of equipment with moisture-fungus-proofing paint.
  FIELD-EXPEDIENTS
  6-139. LRSU can greatly improve their ability to communicate in the jungle by using expedient antennas.
  Moving units are generally restricted to using the short and long antennas that come with the radios.
  However, when not moving, field-expedient antennas increase range and improve reception.
  COLD WEATHER OPERATIONS
  6-140. In very cold weather, ionospheric storms and night lights, such as the Aurora Borealis, can
  degrade sky-wave propagation and disable radio communications. Static can block frequencies for
  extended periods; changes in the density and height of the ionosphere can fade a signal for weeks. When
  these disturbances occur is difficult to predict. However, when they do, radio operators must be ready to
  use alternate frequencies, or other means of communication. Put radios in vehicles, if possible. This
  simplifies transport and provides shelter for radio operators. It also helps alleviate grounding and antenna
  installation problems caused by the cold: permafrost and deep snow limit grounding. Frozen ground
  conducts electricity too poorly to propagate ground waves well. To improve ground wave transmission,
  install a counterpoise far enough aboveground to prevent the snow from covering it. When installing
  antennas--
  • Handle the mast sections and the antenna cables carefully; they become brittle at very low
  temperatures.
  • Run antenna cables overhead to avoid damage from heavy snow and frost. Use nylon rope for
  guy wires rather than cotton or hemp. Nylon absorbs less moisture, so it is less likely to freeze
  and break.
  • Use extra guy wires, supports, and anchors to help antennas withstand heavy ice and wind
  loading.