Online RF Calculators by Federal Custom Cable

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