There are hundreds of "formula" sites on the web - for calculating everything from 3 phase power requirements to 5 gig antenna dimensions. Instead of reinventing the wheel, here are some favorites that can save you some time. Also included are info links. The best place to start?
Starting Out - Finding your way around fcc.gov
FCC Calculators and converters
FAA tower lighting issues including lamp outages
"Sun Fade" Calculator: For everyone using satellite dishes, here's a link to a sun fade calculator to figure your spring and fall outages.
DATUM Conversions: Most new devices record in NAD83. Working with FCC databases will require conversion either to or from NAD27. You can to that here.
Tech Formulas: (does anyone use "formulae" anymore?) NB: The accuracy or lack of accuracy of any of these calculators is determined by the originator. Please give them credit for working or the Bronx cheer if they don't give you what you need!
dB and Power Calculator
Air Coil Calculations
Resistors in Parallel
Transmission Line Calculators
Resonant Frequency Calculator
General Radio Formulas and Programs
More General Calculators:
Regulator Current Limiting Resistor Calculator
Transistor Bias Voltage Calculator
Capacitance Time Constant Calculator
Four, Five, Six Color Band Resistor Line Calculator
Transistor Switch Saturation Degree Calculator
LED Light-Emitting Diode Current Limiting Resistor Value
Flat-Plate Capacitance Calculator
Wheatstone Bridge Calculator
Constant Current Source Calculator
Inductance And Capacitance Calculator
Ohms Law Calculator
FET buffer calculator
Voltage Divider Resistance Calculator
Parallel resistance calculator
RC filter cutoff frequency calculator
Temperature Conversion Calculator
Cube root calculator
...and a slew of calculators for power, horsepower, and lots more here.