antenna-theory.com

[mikmarbar]

Hey guys, i am a bit of a novice when it comes to antennas so forgive my ignorance if it is obvious.

I am currently messing around with a point to point communication network using a 430MHz, 1/4 wave whip antenna that has a VSWR of around 2

I wanted to know how to calculate the distance that this antenna is able to transmit, (i believe the correct term would be the radiation pattern?) in other words I want to know given the antenna I have, if I hook up a transmitter with different powers (1W, 500mW, 100mW) can i calculate the maximum transmit distance.

I also wanted to know what effect the standing wave ratio truly has on the network, I am aware that the closer it is to 1 the more power is getting transferred into radiation, so is it going to make a bigger difference getting a radio that can transmit at a higher power or a different whip antenna that has a better SWR, and is 2 a bad SWR to have?

thank you for your help and again sorry if the question is a little naive

[bigSteve]

VSWR of 2 is not a big deal at all. This will lower your transmit power by less than a dB.

To calculate the distance, you need to know what the required received power is. Then start with Friis Transmission equation:
http://www.antenna-theory.com/basics/friis.php

In urban environments the signal dies off much quicker than that.