Alan wrote:

A year or two back I wanted to annoy a friend with the "ring him and hold
phone by the audio vario" trick, but at 3000ft over Huntingdon, i.e.
above a flat bit of Cambridgeshire, there was no signal at all. I was
using a GSM phone, so the radiation pattern was evidently flat enough the
exclude not only Huntingdon masts but also those further away (Cambridge,
Northampton). This makes sense to me. Why should a telco waste
electricity transmitting a hemispherical pattern when a pancake pattern
will give a better signal strength for less radiated power throughout its
service area.


Interesting. Generally, the attenuation possible from an antenna depends
on the angle of elevation, and if you are 5 miles from the tower, at 3000
feet, you would be 6.5 degrees of elevation above horizontal, which should
be well within the pattern of the antenna. (Any reduction would be easily
made up by the very clear path to the tower.)

More phones means the cells have to be smaller. Many/most of towers
around here have a number of what appear to be VERY directional
antennas, and the towers are low ( 100'), and surely very low power,
because the next tower is only a mile or two away. They aren't going to
reach out to 5 miles, even under the best of conditions. The loss of
signal at 3000' or so is common where the cells a small, such as near
cities. The rural areas often work to higher altitudes, if they have
coverage in the area.

My old analog/TDMA phone used to work very well to even 15000' agl, but
my new TMobile GSM phone is unreliable off the ground, and worthless at
our 7000-9000 agl soaring altitudes, even in our mostly rural Eastern
Washington.

I suspect there is a lot of variation between providers; even so, I
think it's just going to get worse as the cells get smaller yet.

--
Eric Greenwell - Washington State, USA
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