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Formulas

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Attenuation

Voltage: Av = 20log(Vout/Vin)

Power:Ap = 10log(Pout/Pin)

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Electrical Length

L(nsec) = d(ft) x (√K) / Co

Where K = dielectric constant and Co = speed of light » 1 ft/nsec

 

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Impedance

Transmission Line: ZO = √(L/C)

Where C = capacitance, L = inductance

 

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Propagation Delay

PD (nsec/ft) = (√K)/Co

Where K = dielectric constant and Co = speed of light » 1 ft/nsec
 

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Reactance

Capacitor: XC = 1/(2πfC)

Inductor: XL = 2πfL

Where f = frequency, C = capacitance, L = inductance
 

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Velocity of Propagation

VP (%) = 1/(√K) x 100

Where K = dielectric constant
 

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Wavelength

λ = Co /f (in air)

λ = Co /(f x √K) (in any dielectric)

Where Co = speed of light and f = frequency

For example: λAIR = (1.18 x 1010 in/sec)/(5 x 109 Hz) = 2.4 inches @ 5 GHz

λFR-4 = (1.18 x 1010 in/sec)/((5 x 109 Hz)(√4.5)) = 1.1 inches @ 5 GHz