Prevending Feedback in DAS

Feedback or Oscillation in a Cell Phone Booster System is typically a direct result of the signal from the internal antenna and the external antenna crossing paths and happens for a variety of reasons.

  1. Antennas are too close to one another
  2. Signal gets out of a window or open door and enters the signal stream of the external antenna
  3. The external antenna is directional and facing towards the internal antenna
  4. The internal antenna is directional and facing towards the external antenna

Typically when this interference takes place, the amplifier will shut itself down for safety reasons both to protect the amplifier from overheating or malfunctioning and to eliminate any noise getting back to a cell tower which could cause damage to the tower. Many amplifiers such as the CM2020-80 featured on Cellular Solution’s website have gain control so that the gain on the amplifier can be turned down to accommodate the feedback or oscillation. If attenuating the signal does not remedy the problem or if the amplifier has to be turned down too low, some other options are:

  1. Create isolation (separation) between the antennas by moving them further apart. Sometimes vertical separation is as good as horizontal so a longer pole or mount may be beneficial in creating this distance.
  2. Utilize a directional antenna as the donor (outside) antenna
  3. Place the donor antenna at the edge of a roof and position it away from the building
  4. Mount the internal antenna on a lower floor of the home or building if available
  5. Mount the internal antenna away from a window that is on the same side of the house or building as the donor antenna
  6. Mount the internal antenna away from a commonly used outward door that is on the same side of the house or building as the donor antenna
  7. Utilize in-line attenuators

As can be seen, there are several opportunities to overcome this particular obstacle. There are many options not listed that with some craftsmanship and common sense can also eliminate the feedback or oscillation issue within the cellular repeater system. If all else, contact one of the highly skilled technical experts at Cellular Solutions at 1-877-233-6673.