User's Manual

Hardware Installation Guide Radio Site Planning
02030311-10 Airspan Networks Inc. 5-11
5.9. Considerations when Using External
Antennas
Notes:
1) To avoid unnecessary RF cable loss, use short-length cables and with low
attenuation.
2) Antennas should have a VSWR of less than 1:1.5.
3) Ensure BSR and SPR/IDR use the same antenna polarity (i.e. vertical or
horizontal).
4) When using an omni-directional antenna, choose a type providing a wide
vertical beam width (of at least 8°) to allow connection of closer CPEs.
5) Antenna must be DC grounded.
5.9.1. Cable Loss
Airspan's ASWipLL radios provide transmit power compensation for power
attenuation caused by cable loss (in cable connecting to external antenna). Cable loss
is the loss of radio transmit (Tx) power as heat, and directly proportional to cable
length and quality, and operating frequency.
To adhere to Effective Isotropic Radiated Power (EIRP) limitations in the regulatory
domain (country) in which you are operating your ASWipLL system, when
purchasing antenna cables, take into consideration cable loss per cable length. EIRP
is calculated using cable loss:
EIRP = max. transmitter power output + antenna gain - cable loss
For example, FCC regulations state that when operating in unlicensed bands, the
external antennas must provide an EIRP of less than or equal to 36 dBm to prevent
interference with other radios. Thus, knowing this EIRP parameter, you can choose
the cable that ensures adherence to this parameter value.
The table below lists examples of cable loss per cable length.