Online calculators are a great convenience even in the 'The
Age of the Phone App.' Website-based calculators have the advantage of being accessible from any device,
and without having to download and store it in memory. Federal Custom Cable has a fairly extensive collection
of basic electrical, RF and microwave type calculators.
They are all conveniently listed on a single page, as can bee seen at the left (I did a screen capture
with all the categories expanded).
Before using any calculator I have never used before, I validate its accuracy with known quantities.
Here are a few examples of the calculators, with parameters entered to quickly check the results.
The first one is a VSWR-to-Return Loss converter, where I input a number that every RF engineer and
technician should have memorized for easy reference: 1.458:1 in VSWR equals 14.58 dB in return
loss. Note the same numerals are used with just a shift in the decimal point.
VSWR-to-Return Loss Calculator
In these days of surface mount components, fewer and fewer people need to be able to decode resistor
color stripes. The old mnemonic I have always relied on, albeit highly unacceptable in today's special
snowflake world, is "Bad(black=0) Boys(brown=1)
Ravage(red=2) Our(orange=3) Young(yellow=4) Girls(green=5) Behind(blue=6) Victory(violet=7) Garden(grey=8) Walls(white=9)." My excuse is that I'm
just south of 60 years old and was taught it by a hardened U.S. Air Force technical school instructor
(or maybe it was even before that by a hardened master electrician in my electrical vocational classes
in high school). Regardless, if you can't remember the color band numbers, FCC is there to help.
4-Band Resistor Color Code Decoder
Another relationship all RF Cafe visitors should know is that is free space with a relative dielectric
constant of 1, the wavelength of 300 MHz is 1 meter. The equivalent in English units is 3.28 feet.
One full wavelength is 360 degrees.
Electrical Length Calculator
Posted February 16, 2017