Study is the thing I do every moment I get to.
There's a lot of documentation online that I have downloaded in the past month about tunable filters.
Problem is that all of them are > 1 GHz frequencies.
If my situation were in that range, believe me when I say this, you wouldn't even know I exist.
But, the frequencies I am working with go from 20 MHz to 500 Mhz.
At those frequencies, as you know, microstrip is complicated to build if not impossible due to size limitations.
However, I am interested in finding out more about what you said.
Varying the resistance is something that I have enough resources to follow.
Any website or publication you may suggest?
I would greatly appreciate it.
You also mention DSP as a common technology used for this.
I have not worked with DSP so far.
I will make note of that and see what I can find about it.
I have donwloaded some IEEE papers as far as my subscription allows me.
There are others but those you have to pay, which I don't mind.
Though I would like to know if the information there will be useful before buying.