Cascaded L-section matching network between 50 ohm source and 25 ohm load, @ 27.0MHz, using 1 L-section, 2 L-sections and 3 L-sections, all of the three configuration would matching perfectly at exactly one frequency point, that is 27.0MHz. However in many case we want good matching on a wider bandwidth. The question is, can a 3-section matching network works better than a single L-section?
Well, from the frequency response plot and reflection plot, we can see the bandwidth of 3-section network is not significantly wider than that of the single section.
Some other matching network topology need to be investigate to achieve the goal of broadband matching.
I looked all your blog, everything is very interesting. It is a pity that there are few schemes. But very interesting experiments, I also wonder RF, RC, receivers and transmitters. But I'm currently working on the 144 Mhz range. I made my project on MC2833, the lack of many harmonics. It is impossible to keep a filter that will provide BW = 10-15Mhz, attenuation in the 3db bandwidth, well, suppress harmonics 132 and 156 Mhz at 40-60 dBm. https://www.youtube.com/watch?v=9i4784oPt-I
ReplyDeletefor power saving reason, it make sense that fm transmitter is biased as class b, class b chop half wave off and thats why it generate quite heavy harmonics, there are a LC tank in the output stage it helps rejecting harmonics if, a proper length antenna, i am expecting to see a much better spectrum if you use another antenna to pick up the transmitter and show it on spectrum analyzer
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