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Table shows typical SWR relative to installed wire length. SWR will vary based on topography, proximity of nearby structures, configuration of the antenna wire and choice of ground or counterpoise. For best results, use the longest wire shown on the table that will fit your installation constraints. Installing the antenna wire as an Inverted L ...
This project assembles a 49:1 ferrite-core (“FT”) type #43 transformer that matches 50 ohm input to 2500 ohm end fed antenna. It is optimized for 3.5/7/10/14 MHz but will work reasonably well on all amateur bands from 80 meters thru 10 meters with a 135 foot length of wire and a short connection to ground.
An 80-10 end-fed half-wave antenna can be a very good performing part of an HF station. But its performance depends heavily on a well-designed and carefully constructed 49:1 unun, which matches the long wire impedance to within tuning range of operation. But the perfor-mance of an end-fed antenna is also very dependent on height above ground.
In my main set-up I use a HyEndFed 8 band 400W antenna with 2 counterpoises (beside my home made). One 20 meter long (the right cable in the picture) and one 8 meter long (the down-left). The top wire is the antenna and you can see my first choke and the antenna cable feed.
Table shows typical SWR relative to installed wire length. SWR will vary based on topography, antenna wire configuration and use of ground or counterpoise. For best results, use the longest wire shown on the table that will fit your installation constraints.
Installing a 1:1 choke balun at or near the unun will not allow the coax shield of the feed line to be used as a counterpoise. Wire lengths for the 4:1 ratio in models 4130, 4132, 4134, 4932 and 4935. Usually any wire length that is non resonant, like those shown above, will work with the 4:1 ratio.
22 lut 2021 · The following is a list of materials required to make a 49:1 unun impedance transformer for an end-fed half wave antenna. You will also need a half-wavelength length of wire (14 or 12 gauge typically) in order to construct an antenna radiator for whichever ham band you choose.
