"Charles" wrote in message
. ..

"Arfa Daily" wrote in message
...

"Fred McKenzie" wrote in message
...
In article .com,
" wrote:

I can't remember my formulas. If I have a transmitter that puts 1 watt
into a beam antenna that has a gain of 8.0DB what is my EFR? Please
show the work. I need to be able to demonstrate this to a customer.

Lenny-

Charles' method should work for you. If a customer asks, you need to
know more about the antenna's gain - is it compared to an isotropic
antenna (dBi) or compared to a dipole (dBd)? Note that 0 dBd = 2.1 dbi.
An antenna with isotropic gain of 8 dBi would have a gain of 5.9 dB with
respect to a dipole.

The isotropic gain is useful for calculating field strength at a
distance, but gain with respect to a dipole is easier to measure!

Fred

The calculator that I pointed Lenny at does it for dBi and dBd. A lot
easier to just show your customer something that goes ahead and does the
job, rather than faffing about in front of him with a calculator, working
with a formula and numbers that you're not totally easy with ...

He posted "Please show the work."

That is true, but I assumed that he asked this such that he could
re-familiarise himself with the math so that he would be able to demonstrate
to his customer how to work it out. Based on my many years of dealing with
customers, and making myself look dumb on occasion by trying to explain
something that I was not properly familiar with, I just felt that it might
look slicker to the customer to be able to just enter the figures and see
the results, for both comparison schemes, instantly shown. If he really
wants to go down the route of doing it all himself, Google will turn up many
hits if he just enters " Antenna ERP " as the search string.

Arfa