Will a larger antenna provide more range with same power output?

[Couldbeflying]

Hello,
I am using 2 small serial transceivers (from Active Robots). Included
were 2 (2 inch) stub antenna. Before I waste my money.... If I buy 2
larger "rubber duck" (8 inch) antenna (with increased db), will I
increase transmission range even though I won't be increasing wattage
output of the transceivers?

Thanks for your time
Richard

 

[Joel Kolstad]

I am using 2 small serial transceivers (from Active Robots). Included
were 2 (2 inch) stub antenna. Before I waste my money.... If I buy 2
larger "rubber duck" (8 inch) antenna (with increased db), will I
increase transmission range even though I won't be increasing wattage
output of the transceivers?

Assuming:

1) The larger antennas were designed for the frequency you're using
2) The receiver can still "see" the transmitting antennas (a higher gain
antenna simply takes the energy provided to it and concentrates it into a
narrower region, just like a lens -- for the antennas you're using, the
regular bagel-shaped radiation pattern gets "squished" into a flatter bagel)

Then, yes.

Note, however, that often variations in received signals due to your 'bot or
people moving around can easily be +/-10dB or more, and therefore for antenna
gains you can reasonably obtain (2dBi->8dBi), you can take a system that
receives a *lot* of bit errors and reduce their frequency, but usually you
don't go from "lots of errors" to "no errors."

 

[PeteS]

Assuming:

1) The larger antennas were designed for the frequency you're using
2) The receiver can still "see" the transmitting antennas (a higher gain
antenna simply takes the energy provided to it and concentrates it into a
narrower region, just like a lens -- for the antennas you're using, the
regular bagel-shaped radiation pattern gets "squished" into a flatter bagel)

Then, yes.

Note, however, that often variations in received signals due to your 'bot or
people moving around can easily be +/-10dB or more, and therefore for antenna
gains you can reasonably obtain (2dBi->8dBi), you can take a system that
receives a *lot* of bit errors and reduce their frequency, but usually you
don't go from "lots of errors" to "no errors."

Just as an aside, increasing the transmitter power (what the OP alluded
to as 'wattage') doesn't yield a whole lot (as I know Joel is aware,
but the OP may not be, and that's who I'm addressing) unless you
increase it a LOT.

If you get (for instance) 3dB better sensitivity with your antenna,
it's equivalent to doubling the transmitter power (assuming identical
radiation patterns).

For a perfectly isotropic antenna, to double the range of your system
by increasing the transmitter power, you *square* the transmitter
power. That's why we try to get the increased sensitivity in the
receiver - simpler and less likely to make a space heater

Cheers

PeteS