On Tue, 20 Sep 2011 18:48:26 -0500, amdx wrote:
I'm curious, I'm in a marina that has an L shaped concrete parking lot
with water on the inside of the L-- right were the arrow points.
I'm docked in the corner of the L, and want to send a signal everywhere
but the the water.
What does the pattern look like if I use a corner reflector but put
the source on the outside of the corner rather than the inside?
Dunno, and I'm too lazy (and tired) to build an NEC2 model. I don't
think it would work the way you propose anyway.
My guess(tm) is that you want to send RF in two directions, 90 degrees
apart. That's easy. Use 2 directional antennas, such as patch or
panel antennas, and drive them with a power splitter. You'll get half
the transmit power to each antenna, but the receive sensitivity will
be the same as it would be with a single antenna (minus about 1dB for
the power divider loss).
I'm at 433 Mhz now but may need to go to 2.4 Ghz.
The app is a driveway sensor that triggers a pocket carried receiver no
matter where I'm at on the L.
Ok. 433MHz has very limited range mostly because of the crappy
receivers, gutless transmitters, and miserable antennas. Improvements
to any of these will increase the range. I suggest a better antenna.
As it stands the transmitter range is not far enough, I only need 50
yards down leg of the L.
150 ft is difficult at 433Mhz. My cheapo La Crosse weather station is
only reliable up to about 20ft. My vehicle remote door unlocker is
good for only about 30ft. However, it is possible to buy long range
433MHz remote control switches, with much longer range. 2.4Ghz is
fine, but what are you going to use as a receiver?
Anyway, look at commercial wireless car alarms and notice that the
better variety have a small bi-directional remote, that can act as a
pager to receive alarms, and also be used as a transmitter to
enable/disable the alarm. These radios are probably better than
whatever you're using (and are probably on 900MHz). You might also
consider using a real pager and a POCSAG encoder.
--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060
http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558