Valentino’s homebrew ferrite sheet antenna.
Many thanks to SWLing Post conttributor, Valentino Barbi (I4BBO) who writes detailing a novel approach to FSL antenna design.
Please note that I translated Valentino’s message from Italian to English via Google translate so please forgive any errors. Valentino writes:
FSL antenna radio enthusiasts typically use numerous ferrite bars with high cost, weight and scarcity,
Ukrainian ferrite bar producers have now finished stocks and have raised their prices.
Normally you use this site to build FSL antennas:
http://www.am-dx.com/antennas/FSL%20Antenna%20Design%20Optimization.htm.I’ve been experimenting with a new antenna design for about 10 days comparing it with a classic FSL with 20 ferrite bars.
Listening to the audio signals are the same, only instrumentally the antenna FSL in ferrite film
Loses -2dB.
The construction is very simple in that the two ends overlap 5 mm.
I did this:
- I took a sheet of A4 paper, I cut 5mm paper at one end.
- I laid this sheet on a 10 cm (10 cm) diameter PVC tube.
- The uncovered part of the tube is cut, now we will have exactly the exact diameter to fix the A4 sheet of ferrite with the overlap of 5 mm.
As for where to source a ferrite sheet, after much research I discovered this supplier almost by accident:
Click here to view the product page and ordering information.
In summary, the main advantages of this antenna design is weight, cost and availability of A4 sheet of ferrite.
Click here to follow Valentino’s antenna project on his website.
Fascinating, Valentino! Please feel free to share any further information about this FSL antenna as you experiment. It’s true that ferrite bars are becoming difficult to source. Sounds like this is an affordable alternative antenna design for ultralight DXing.
Unfortunately, ferrite sheet in the USA is outrageously expensive, twice the price and half the amount of ferrite as the Ukrainian bars/rods. A rating of 400 is good for MW antennas and 150 or less is good for lower SW use. The Fair Rite stuff from Mouser Electronics for a larger project I have in mind will need 8 of the 120mm sheets for about $150 with shipping (Fair Rite Part# 38M6020AA1212). Now that much of the Eastern European stock is depleted, maybe this is an OK price but still seems outrageous based on how much it must cost to make it.
And the Chinese made stuff, who knows if it is even ferrite?!?!
Some manufacturer somewhere needs to step up and make and sell this stuff much cheaper and tested for the initial permeability needed for radio projects.
“I laid this sheet on a 10 cm (10 cm) diameter platinum tube…..” From the looks of the picture I’m going to say Google might have mistook PVC for platinum. Going with PVC might help keep costs down 🙂
Agreed! How did I miss that? I’ve amended the post.