rad1o

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= D1POLE antenna

https://www.dk0tu.de/users/DB4UM/c3d1pole/


== Q&A


=== Can anyone explain how to properly wire the thing up? Currently there isn't much explanation. (What does "If you want to calculate the length of one wire of the D1pole use the simple formula: 1 wire on the left, 1 on the right" mean?)

I am only an armchair antenna builder, but the following might help: A [[https://en.wikipedia.org/wiki/Dipole_antenna|dipole antenna]] is usually a half-wave antenna, so the total length is half the wavelength of the corresponsing frequency. The wavelength at 144MHz is 300000000m/s / 144000000 Hz = 2m. Half that would be 1m, and because the dipole has two arms, each arm is again half that length, so we need 2 arms with 0.5m length each for 144MHz. We get the same by plugging the 144Mhz in the formula on the d1pole page (75/Mhz = length).

The coiled part on the bottom is a [[http://www.hamuniverse.com/balun.html|balun]] (well, technically it's not really a balun, but an air choke), which is needed because a dipole antenna is balanced and the feeding coax cable cable is unbalanced. This has to be compensated for, otherwise the feeding cable becomes part of the antenna, which is not desired.

So my attempt for a mini build howto:

* Cut a length of RG174 (1m or so), crimp a SMA connector to one end, coil it around the bottom of the T-shaped d1pole part through the holes.
* Cut two lengths (Length in meters = 75 / frequency in MHz) of any single core wire, feed them through the holes at the left and right side of the d1pole part for pull relief.
* Solder the two wires to the RG174, one to the core, and the other one to the shielding.
* done 8-)
rad1o

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