🚀 go-pugleaf

On Wed, 14 Jul 2010 11:00:19 -0700, "John Richards"
<JR@blackhole.invalid> wrote:

>"Peter Lawrence" <hummbaby@aol.com> wrote in message news:i1ktio$9q1$1@news.eternal-september.org...
>> On 7/14/10 5:32 AM, SMS wrote:
>>>
>>> 3) increasing power helps for transmitting but not receiving.
>> 
>> But that's were the most help is needed.  The biggest problem with today's 
>> tiny cell phones is not that they can receive a signal from a cell. tower 
>> but that they are not able to transmit back a signal that can reach the 
>> cell. tower.
>
>Not so. The receive antenna on the tower is not under the tight size
>restrictions you have on a hand-held. The towers employ high gain
>antennas and complex (physically large) receiver circuitry.

There is no free lunch in the radio biz.  If you increase the antenna
gain in one direction, you have to borrow the gain from another
direction.  Antennas do not amplify the signal.  They direct the
signal.  So, if you want to increase the gain of the antenna, you'll
need to add more antennas on the tower to cover the lost coverage
areas.

For a given style of antenna, a 3dB increase in antenna gain requires
an antenna that's twice as big.  By the numbers...
  Gain      Increase in antenna size
   3dB         2x
   6dB         4x
  10dB        10x
  20dB       100x
  30dB      1000x
So, to compensate for a -30dB drop in iPhone 4 signal strength, you
would need an antenna that's 1000 times as large.  You would also need
1000 such antennas to cover a 360 degree circular coverage pattern.

You're also wrong about cellular providers not being restricted on
antenna size on the tower.  The various NIMBY motivated ordinances
have resulted in disguise antennas, tower restrictions, visual impact
committees, exposure rules, and all manner of restrictions.  On a
leased tower, the tower service company charges handsomely for tower
space, which usually is at a premium.

Incidentally, the tx power from the cell site is legally limited to 1
or 2 watts per carrier (i.e. per handset).  To save on the electric
bill, maintain amplifier linearity, and reduce RF emissions, the cell
site usually runs far less power output.  Even so, it's usually more
than what the handset delivers in TX power.  That's why the handset
can usually hear the cell site, but the caller on the other end
complains that the handset is "breaking up".

-- 
# Jeff Liebermann 150 Felker St #D Santa Cruz CA 95060
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