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The all band doublet antenna is nothing more than a 1/2 wave dipole cut for your lowest operating frequency and fed with twinlead, ladder line, open wire, etc to a tuner that will accept a balanced line connection.
Windowed ladder line is available from many different amateur radio retailers (you’ll even find it on Amazon). Look for 450-ohm windowed ladder line, and choose a length that will reach from the center of your antenna to wherever the balun will be located. There will probably be some ladder line left over, but that’s okay.
5 Ιουλ 2015 · The classic center-fed 80 (or 160) meter doublet, with ladder line and a tuner, will work all HF bands, though some trimming of the line may be needed to get it within the tuner’s range on one or more upper bands.
The DBJ-1: A VHF-UHF Dual-Band J-Pole. Searching for an inexpensive, high-performance dual-band base antenna for VHF and UHF? Build a simple antenna that uses a single feed line for less than $10.
Years ago I ran a 160 meter doublet with window line to a 1:1 bifilar choke & 15 feet RG-8 to an MFJ-993. It worked well & tuned on all bands. Then I brought the ladder line all the way in to the 993 and used its internal balun, and it seemed to work just a little bit better.
5 Μαΐ 2021 · Ladder line encloses enough area to make an effective receiving loop antenna for HF, but it can also do more interesting things. Below is a discussion of using lengths of ladder line as a receiving antenna for the HF and MF bands.
Here is a downloadable table of doublet/dipole antenna lengths, multiples of 1/8 wavelength and ladderline feedline lengths that should be avoided and two that might be good choices.