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[SOLVED] Frequency mixer simulation termination

Hawaslsh

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Hello,

Picture1.png
I am playing around with a frequency doubler. For now the doubler is just a diode. The input frequency is 5.8 GHz and the doubled output is 11.6 GHz. The diode is terminated with an antenna whose resonant frequency is 11.6 GHz. A note about the filter, its pretty much ideal BPF, presenting a near open at frequencies outside the pass band.
Picture2.png
The antenna, S11 response plotted above, basically presents an open at the fundamental for the circuit, 5.8 GHz, and close to a match at 11.6 GHz. Looking at power spectrum plot above, I am plotting the powers at node at the blue dot. Given the antenna looks like a match at 11.6 GHz, its not unexpected to see almost no power at 11.6 GHz.
Picture3.png
To try and get an idea of how well the diode is working and the conversion loss, i added another ideal filter. I am still plotting the power at the same node. With the filter present, I can see power at the 11.6 GHz harmonic. My question is: is this second filter needed in reality? The filter has a S21 of 1 at 11.6 GHz, does the simulator need its presence in order to actually a voltage at the second harmonic?

Hope that makes sence,
Thanks
Sami

- - - Updated - - -

The Simulator considered the Antenna a DC short. Adding the BPF prevented this. Sorry to waste people's time, should have spent more time investigating
 

vfone

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Why the simulator is consider a patch antenna as a DC short, when there is no DC connection to the ground in a patch antenna design?
 

Hawaslsh

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Why the simulator is consider a patch antenna as a DC short, when there is no DC connection to the ground in a patch antenna design?
I originally simulated the antenna down to 1 GHz. When it extrapolated the results down to DC for the large signal simulation, I suppose it gave the antenna some DC value.
 

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