🚀 go-pugleaf

"Pascal" wrote:

> I am considering that option to gain reception in remote areas.
> Anyone with on mounted on his car ?

Yes.  I've tried various, and find a high-gain whip antenna the
best.  But get one that's wired from phone to antenna - not an
RF-coupled "through the glass" one.  A whip aerial is
omnidirectional (if it's not physically obstructed).

> What is the maximum gain I can expect ?

> I have seen 7dB and if my memory is good from uni, it means 4
> times better as it doubles every 3 decibels.

I've tried various from 3 to about 5, and find the 5 excellent.

Bear in mind that you're limited by Timing Advance (TA) in a GSM
phone.  This is the compensation made for the delay caused by the
speed of light, to ensure that the bursts transmitted by your
phone get to the tower at exactly the right time for
synchronisation with your allocated timeslot.

It's a 6-bit field, so values range from 0 to 63.  At 553.5
metres per step, that gives GSM an absolute maximum range of 35
km.

There's a workaround to this limitation, using pairs of timeslots
in half-capacity cells.  Extended Range, and Enhanced Extended
Range cells have maximum ranges of 72 and 121 km respectively.
But they're rare.  In general, you might "see" cells further then
35 km away, but you won't be able to use them.

> I have found some Omnidirectional antenna designed for both GSM
> and GPS.
> Is that a better alternative to the vertical antenna ?

If these are the compact, stick-on, "phased array" types, I've
found them reasonably good, but whip antennae better.

John