GhostLoveScore
- Nov 27, 2016
- 71
- Joined
- Nov 27, 2016
- Messages
- 71
Hi everyone
I have a test circuit, oscillator and emitter follower.
This is related to this thread
https://www.electronicspoint.com/threads/help-me-calculate-output-impedance.282132/
The problem is this. Antenna is simple ground plane antenna cut to a quarter wavelength. If I solder it to emitter of emitter follower the signal is OK. But if I solder a piece of coax, RG58 and try to get antenna to radiate that way, it doesn't work. The signal is very very weak.
What I think is happening here: I didn't match impedance of emitter follower (output impedance) and antenna. When I connect a coax that has 50 ohms impedance there is large mismatch and no power can get through the coax to the antenna.
It's visible here that SWR of 6:1 causes 50% power loss. In my case it's very easy to have even bigger impedance mismatch.
Do you agree this is the case?
The problem is that right now I am making RF circuits without having an oscilloscope. If I had oscilloscope there is a way to measure output impedance of the amp. LC matching network, is useless if I don't know impedance of both amplifier and the antenna. What do you suggest I should do?
I have a test circuit, oscillator and emitter follower.
This is related to this thread
https://www.electronicspoint.com/threads/help-me-calculate-output-impedance.282132/
The problem is this. Antenna is simple ground plane antenna cut to a quarter wavelength. If I solder it to emitter of emitter follower the signal is OK. But if I solder a piece of coax, RG58 and try to get antenna to radiate that way, it doesn't work. The signal is very very weak.
What I think is happening here: I didn't match impedance of emitter follower (output impedance) and antenna. When I connect a coax that has 50 ohms impedance there is large mismatch and no power can get through the coax to the antenna.
It's visible here that SWR of 6:1 causes 50% power loss. In my case it's very easy to have even bigger impedance mismatch.
Do you agree this is the case?
The problem is that right now I am making RF circuits without having an oscilloscope. If I had oscilloscope there is a way to measure output impedance of the amp. LC matching network, is useless if I don't know impedance of both amplifier and the antenna. What do you suggest I should do?
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