Hello,
When I connect my antenna (2.45 GHz with output power of -10 dBm) to the rectifier (2.45 GHz) there is no output voltage, however when i injected the same power (-10 dBm) in the same frequency (2.45 GHz) i get a output voltage of 0.2 V
There is no problem with matching or polarisation.
How to correct this issue?
It might be due to difference in AC coupling / DC current path, e.g. the antenna or generator in one case may have DC blocking capacitor on the ouput or maybe just the opposizte - inductor to ground (so DC connection to ground). I hope it helps.
We should first recall that Rf "rectifiers"since the signal is in general rather small usually work in the square law region i.e. the output voltage is proportional to the input power (rectification takes place for small Rf signal on the second derivative of the diode characteristic. A DC return in the diode may be important; And did you operate CW or with some amplitude modulation? And did you check the the output power from your receiver antenna is really -10 dBm?
yes i operate CW , no there is no amplitude modulation
yes the power -10 dBm measurated with the spectrum analyser
if the power is equal at the input of the diode (rectifiers) then the measured results should be also equal..maybe one of the diodes is dead?
There are multiple reasons why this could be the case:
i) your antenna was designed at a different frequency then what you are transmitting at and the antenna is not picking up much RF power to give the rectifier to convert to DC.
ii) your antenna is designed for the proper frequency but your antenna impedance is mismatched with the input impedance of the rectifier circuit and hence the RF power gets reflected back out.
iii) the gain of your antenna is poorly designed and depending on the path loss you may not be actually be receiving -10 dBm of receive power as you thought you would.
iv) the received power by the antenna may be too high and impedance mismatch may damage your input semiconductors (although this reason is probably unlikely in your case).
With the info you gave, its not enough to discern what exactly is the problem, is your antenna a simple patch or is it more complex?
i) all of them in the same frequency 2.45 GHz.
ii) the is a good matching all of them near 50 Ohm
iii) i used the spectrum analyser it is -10 dBm
iv) no it always work with the RF generator
i tried both simple and complex antenna
the question why it works with the Horn antenna but not working with patch antenna ?
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