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Antenna Formulae
 
Wavelength and Frequency
λ = v / f Where
λ = Wavelength in feet
v = Velocity of propagation in feet per second
f = Frequency in Hz
f = 1 / T Where
f  = Frequency in Hz
T = Time of one wave period (cycle) in second


Path Loss and Vertical Dipole Isolation
Path Loss (dB) = 10log (λ/4πr)2

Isolation (dB) = 28 + 40log (h/λ)
 Where
λ = Wavelength in metres
r = Distance between transmitting
  and receiving antennas in metres
h = Vertical antenna separation


VSWR, Reflection Coefficient (ρ) and Return Loss
VSWR = (1 + ρ)/(1 - ρ) ρ = (VSWR - 1)/(VSWR + 1)
Return Loss (dB) = -20logρ


Power Received by an Antenna
P = PtGtGrλ2 / 16π2d2

 Where
P  = Power received in Watts
Pt = Power transmitted in Watts
Gt = Gain ratio of transmitting antenna
      relative to an isotropic radiator
Gr = Gain ratio of receiving antenna relative
      to an isotropic radiator
λ  = Wavelength in metres
d  = Distance between transmitting and
      receiving antennas in metres


Effective Radiated Power
ERP = G x P

 Where
G = Gain of transmitting antenna relative to
      an isotropic radiator
P = Input Power in Watts


VSWR Vs Return Loss and Effect of VSWR on Transmitted Power
VSWRReturn Loss (dB)Transmitted Power (%)
1.0∞100
1.126.499.8
1.220.899.2
1.317.798.3
1.514.096.0
2.09.5088.9
3.06.0075.0
      *  info@antennaexperts.in

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