There's a post from last year on this topic, but rather than reply to that it may be better to start a new topic.
https://eevblog.com/forum/rf-microwave/ferrite-sleeve-antenna/There's an analysis of these antennas available here:
https://www.osengr.org/Articles/Loop-Antennas.pdfIt's a large document, with a separate chapter on FSL antennas. The gist of it is that while adding a ferrite sleeve to an electrically small loop of moderate diameter (e.g. 4-12 inches) will improve the performance, the gain is not as much as one might think (based on a lot of blog posts around the Internet). The issue is that while this analysis appears to have been well done using E-M simulation software, it is not backed up with experimental data. There are no real scientific comparison measurements of air core vs FSL antennas published today. The best one I could find is a fairly subjective analysis by DeBock.
So, here's what I am wondering about. I'm interested in making some performance comparisons to vet the analysis linked above, but these FSL antennas are hideously expensive to build -- hundreds of dollars. Especially today since most of the really cheap Russian surplus ferrite rods have already been scooped up. While I would like to do the comparison, I cannot justify spending the amount of money which would be necessary to pull it off.
I am wondering if there is someone who:
- Has built one of these FSL antennas, or knows someone who has and would let them borrow it.
- Has the equipment required to do a proper comparison.
- Means to measure the Q of resonated loops, preferably in situ
- Receiver, spectrum analyzer, or similar which can accurately measure relative signal amplitudes
- Could build or acquire a similar air core loop for comparison.
- Has the time and inclination to do it.
I know this is a lot to ask, so I'm not real hopeful about this...but it is at least worth asking.