Antenna upgrade question

[abcd567]

@SDMark
@jaymot

@abcd567

When 50 ohm is 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

 

@abcd567

Input impedance of dvb-t’s tuner chip R820T = 75 ohm.
Reason: The DVB-T USB is designed as TV Reciever, and TV’s defacto standard is 75 ohm
For HAM Transmitter/Receivers, the defacto standard is 50 ohm
As far as I know, the Flightfeeder, FR24 feeder, Kienetic Beast Receivers are all based on HAM standard and have 50 ohm impedance