Need help designing an Antenna!
 

Hi,

I'm trying to design a replacement antenna for a GSM phone. One that
will cover 850MHZ, 900MHZ, 1800MHZ and 1900MHZ (Quad band GSM).

Doing a bit of reading on the internet I came up with an antenna that
is made out of a piece of wire at 1/4 length of the average frequency
(1350MHZ). The antenna is just over 5CM (2 inches) long.

It seem to work fine and I get good reception with the phone but here
are my questions.

- Do I need to take anything else into consideration? Like the
material the antenna is made of?

- Did I even do my calculations right?

Thanks,
zoti