adrastos
Newbie level 5
We had a school project to build an active integrated oscillator antenna at 3GHz. We used the AT42085 as the active device and patch antenna as load.
The result from the spectrum analyzer showed it oscillated close to the design frequency about 7% off, which is fine due to inaccurate transistor model.
The question that I've been wondering is that when looking at the spectrum at a large frequency scale, it looks clean. When I zoom in close to the first harmonic, then I see a lot of small spikes forming the envelop of the first harmonic (kind of like a modulated signal).
I wonder whether this is because the design is not very stable due to poor antenna Q (patch antenna has Q in the range of hundreds). What can be done to make it more stable ?
Any feedback/comments are welcome. Thanks in advance !!
The result from the spectrum analyzer showed it oscillated close to the design frequency about 7% off, which is fine due to inaccurate transistor model.
The question that I've been wondering is that when looking at the spectrum at a large frequency scale, it looks clean. When I zoom in close to the first harmonic, then I see a lot of small spikes forming the envelop of the first harmonic (kind of like a modulated signal).
I wonder whether this is because the design is not very stable due to poor antenna Q (patch antenna has Q in the range of hundreds). What can be done to make it more stable ?
Any feedback/comments are welcome. Thanks in advance !!