[BC] FM Coverage by Part 15 System

[Richard Fry]

Dana Puopolo:
>Part 15 should allow low power (100 milliwatt ERP) FM transmitters
> that can cover a college campus, as opposed to a "wireless microphone"
> type that goes about 25 feet.
_________________

Legal Part 15 FM can do better than about 25 feet.  There is no height 
restriction on the tx antenna, so if it can be installed high enough for a 
clear shot to the receive antenna(s) it should give useful? service to a 
decent FM rx out to maybe a 300 foot radius.

The table below shows calculated Part 15 FM free-space field strengths for 
a clear, reflection-free path...

Meters    Feet      uV/m
  3       9.84    250.00 (FCC limit)
  6      19.68    125.00
 12      39.36     62.50
 24      78.72     31.25
 48     157.44     15.63
 96     314.88      7.81

RF