FSL antenna for SW? #ultralightdx


Hi all! I was trying to make 3 inch FSL antenna for MW band, but I ordered less than necessary of AWG 250/46 litz, and did not get the required inductance (just 180 uh instead of 350 uh). As a result, I had an idea to left small number of turns and make an antenna for shortwave band (maybe 80 or 40 m), adding variable capacitor and coupling coil for connect to reciever. But confuses the fact that the permeability of the rods is too large for SW (400 instead 100), and this type of litz wire is also suitable for frequencies below SW. Perhaps these factors will spoil the quality of the SW antenna and the best way out is to simply order a new litz?

Gary DeBock

Hello Igvitk,

Litz wire and ferrite optimized for the MW frequencies really isn't recommended for SW performance. Especially in a sharp-tuning FSL antenna, going outside the recommended frequency range can really throw off performance, even causing the gain peak to fizzle out completely. My recommendation would be for you to use an FSL antenna design that has been thoroughly tested and proofed out, even if you need to substitute the 250/46 Litz wire for the (more expensive) 660/46 or 1162/46 type. As long as the coil inductance is the same (i.e. the number of coil turns is similar), the antenna should work fine, although the best sensitivity always is provided by the largest diameter #46 Litz wire you can use.

Gary DeBock (in Puyallup, WA, USA)



Thank you, Gary!