Wilson Electronics adapter 971128
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For tranmitting, impedance matching is very desireable. An impedance missmatch means that a 100W transmitter may be able to transmitt say only 70W. To transmit 100W with impedance mismatch, one may have to use a 150W transmitter at substantial higher cost.
In case of receiving, since the power involved is in micro Watts or milli Watts, adding a low cost rf amplifier such as satellite in line amplifier, or Pro Stick’s built-in rf amplifier, can cover for mismatch losses at negligible cost.
Calculation of signal loss in dB for a 75 ohm equipment connected to a 50 ohm equipment:
The FA antenna has an input impedance of 50 ohms, and RG6 coax has impedance of 75 ohms, a mismatch occurs.
However, the mismatch loss when using 75 Ohm cabling with 50 ohm antenna will be very minimal at around 0.177 dB. So dont worry and mix the 75 ohm with 50 ohm system.
How I arrived at figure of 0.177 dB?
When 50 ohm mixed with 75 ohm,
Reflection Coefficient Γ = (75-50)/(75+50) = 0.2
SWR = (1+Γ)/(1-Γ) = (1+0.2)/(1-0.2) = 1.2 / 0.8 = 1.5
Mismatch Loss in dB = -10 log (1 - Γ²) = -10 log (1 - 0.2²) = -10 log 0.96 = 0.177 dB