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 | |
| Effective Radiated Power | |
|
ERP = G x P |
Where G = Gain of transmitting antenna relative to an isotropic radiator P = Input Power in Watts |
| 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 | ||
| VSWR | Return Loss (dB) | Transmitted Power (%) |
| 1.0 | ∞ | 100 |
| 1.1 | 26.4 | 99.8 |
| 1.2 | 20.8 | 99.2 |
| 1.3 | 17.7 | 98.3 |
| 1.5 | 14.0 | 96.0 |
| 2.0 | 9.50 | 88.9 |
| 3.0 | 6.00 | 75.0 |