One of my friends was saying that you buy some type of boost receptor from radioshack. my current pager alarm is decent but i wanna get like a real 1 mile radius.?

 

They make antennas that go around the edge of you window, you could put one on the rear window, that may help.
gmoore

 

where do you get these antenas?

 

Honestly, Im not sure, I heard the owner of my local audio shop talking about them. Basically, you could just find some antennae wire and tuck it around your window seal and have it connected to your pager alarm. That may help.
gmoore

 

if you find out hw to get a 1 mile radius, let us know i would love to have that too.

 

I'm no sort of alarm expert, but i learned some stuff about RF communications in school. I know the length of the antenna matters. There is a math formula to determine proper antenna length depending on the frequency of the signal. I know on j-body.org a really long time ago somoene did the calculation, then took out the wire that was the antenna for the remote entry and soldered in a new wire of the correct length and doubled their range. I don't know if this helps you, but maybe you can do some research and come up with something.
good luck.

 

I'm getting a pager alarm soon so I'm going to try extending the antenna. I know where to get the window antenna here in NZ but not sure about the US, hopefully it should make a difference

 

The Weak point isn't the atena, it's already huge on a Viper 790VX, but it's in the remote they can't fit a huge sensor in it, or they would have the make the unit bigger, and it's fat as **** as it is, and it's a ulgy *** remote as well. Just wait for them to put on one with a 1 mile + range, There is a old unit called Autopage. It's a pager add on, thats it's own unit, it has a 1 mile range and 10 second delay, they are very old units, about 15 to 20 years old, they are fucken huge, about the size of 2 pda, but they work, might want to see if u can find one, they are hard to find tho.

 

Also, Compustar's spread spectrum alarm has a 1.25 mile radius. I think its a 900 mhz signal.

 

just remember, the higher the frequency the more line of site it is. So the DEI 434MHz systems will reach farther than a 900MHz if there is stuff blocking a straight line of site. Otherwise the 900 should reach farther with the same power *IF* you can see the other end receiving.

And antenna length does matter as quoted above. It's the wavelength of the signal vs the length of the antenna, and if you're going to do 1/4 wave, 1/2 wave, full wave, etc. Full wave being the best option but requiring the largest antenna obviously

 

rjr162 you are on the right track.

Lower frequencies will travel farther if the power is the same. One thing you are forgetting is the noise environment that the device works in. If a specific spectrum is crowded than it will get less range. I don't know what shares the 434 MHz spectrum. But you can almost gaurantee the 900 MHz spectrum is crowded.

Probably the best thing you can do to get better range is to impedence match the antenna with the Transmitter (this is why some antennas have a little pot to adjust). Otherwise some of your signal is reflected back into the transmitter and wasted as heat. Ever wonder why some power supplies hum? It is because some of the signal is being reflected back into the supply.


Modified by nsxxtreme at 2:35 PM 6/26/2003

 

look at the old CB's. Alot of them had a SWR setting where you could adjust the output to match that of your antenna's length. Of course it was used best if you adjusted the antenna's length to get the highest output possible, which would be reflected by the SWR and the output power indicators.