greeting,

can a passive repeater will work on my cp. my plan is this: to build a
yagi antenna for 900mhz outside and another antenna, a corner
reflector. is pointing my corner reflector to the yagi will work in
improving the recepcion or should i need a coax cable connected to the
reflector antenna from the yagi? any advise would be appreciated...

thanks,

ian

In passive repeaters, you connect the 2 antennas with some transmission line
(like coax or twinlead or ladder line).
Point one antenna to the station you want to receive, and point the other
antenna to your location.
They make these things to fit on cars for better cell phnone reception - but
they are not directional antennas.

"yhan" wrote in message
oups.com...
greeting,

can a passive repeater will work on my cp. my plan is this: to build a
yagi antenna for 900mhz outside and another antenna, a corner
reflector. is pointing my corner reflector to the yagi will work in
improving the recepcion or should i need a coax cable connected to the
reflector antenna from the yagi? any advise would be appreciated...

thanks,

ian

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

Whenever you use a passive repeater in a path, you split the path in
two. The attenuation is greatest in the first few feet of the path.
After the first few feet, signal strength declines only about 6 dB every
time distance from an antenna doubles. The much greater loss of two
paths (add about 22 dB) versus the loss in a single path is the reason
passive repeaters are unpopular in most cases.

If very high gain antennas can be used with a passive repeater, its high
loss can be overcome. This is unlikely in a cell phone application.
Microwave systems use passive repeaters in unusual cases such as
periscope antennas and mountain top billboard reflectors that are very
large and close spaced.

If one antenna of a back to back pair can "see" one end of a radio path,
and the other antenna can "see" the other end, the pair may make an
effective repeater, but will have much loss.

Best regards, Richard Harrison, KB5WZI

thanks for all advise

ian

My cell phone has a metal that sticks at the back beside the battery.
This is maybe it's antenna. No jack for external antenna. Is there a
way i can connect my self-made antenna to the cp using coax cable? i
cant figure out the ground. I also do not know its impedance. can
someone give me advise if it is possible to connect my external
antenna?

thanks in advance,

ian

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