Further to Richards comments

You can also model a passive repeater reasonably easily. With a
propagation modelling pgm (eg Radio Mobile, UKWTools etc) find out what
the receive signal level will be at the "repeater", then do a coverage
study with that signal from the repeater site.

In my experience the signals are very low and not often worth it. I was
however involved in a setup to get signal on 400MHz into a railway
cutting from a TX site only 1800 metres away. The measured signal in the
cutting was about -107dBm but with the passive setup that came up to
about -87dBm. In this case the cutting was on the side of a mountain (ie
no other usable reflections) and the useful distance from the passive
repeater was only about 200 metres. The repeater was a 14dBi yagi
pointed at the distant TX site coax connected to a 8dBi yagi pointed
down the cutting.

Cheers Bob W5/VK2YQA

Richard Harrison wrote:

Ian wrote:
"Can a passive repeater work on my cell phone?"

how about the connection? can you direct me on how to establish
connection b/w two antennas. say, coax cable.How to connect this to the
two antennas?

thanks & regards,

ian

Hi Ian

The "back to back" antennas of the passive repeater are simply joined by
a transmission cable that suits the antennas. ie If they are 50 ohm
antennas use 50 ohm coax. Think of one of the antennas as a source of
signal and the other as a load (although they work in both directions)
hence the connection is simple.

So the system is;

- The passive repeater consisting of two antennas. One (yagi?) pointed
at the cell tower the other (whatever it is) pointing at the place where
you will be using the cellphone. If you are moving around a bit with the
phone you may wish to use a reasonably wide beamwidth antenna rather
than something too directive.

- If there still isnt enough signal you could mount another external
antenna on the cellphone itself pointed at the passive repeayter antenna.

- Design of the antennas will also include selction of coax etc
connection. You could equally as well built antenas with 300 ohm
impedence and join with them 300m ohm ribbon. Are you building your own
or buying antennas off the shelf? I'd actually suggest some corner
reflectors as they are not as critical as long yagi's and have a more
useful/wider bandwidth coverage. mr Cebik (http://www.cebik.com)has some
corner reflector designs you may be able to scale to 900Mhz.

Cheers Bob

yhan wrote:

how about the connection? can you direct me on how to establish
connection b/w two antennas. say, coax cable.How to connect this to the
two antennas?

thanks & regards,

ian