Course of rf-voltage on a wire.
Directly to the charts Directly to the calculationprogramm KWSINUS02
Dear friends, special for newcomer, every times I hear from the problems if you have only a pice of wire as antenna for shortwave. You don't now where is the optimal input point and what impedance has the wire input?
If you have an antenna book you only can find optimal antennas with beautifull course of current and voltage. But where is the highest or lowest voltage etc. impedance for all etc. the most frequencies? The following charts will show that.
The mathematical formula of cos (lwire) in touch of the 2*pi (like 360°) will calculate all what you need.
f(l)=abs(cos(2*pi/lambda*0.955*lwire)) The result must be absolute, so you have no negative goals.
If the cos(u) = 1, that means high voltage or high impedance, if it 0 then it is a low impedance. The chart will viewing all hamradio bands so you have a overview in two charts, first from 0 to 20m and second 19 to 50m.
With this realization you can build a dipole antenna or a simple long wire antenna with balun. If you accept that the maximal impedance is approximate 1 kohm, you can also calculate the value between 50 and 1 kohm.
Matthias, DO4MAT was stimulated by the "stiff" consideration of the "Course of a rf voltage on a wire" and has a very nice program written which also single frequencies of any number as well as 11 meter band looks and graphically calculate. It is a great supplement to my whole view and Matthias has permitted to me, his programme as a Freeware within the scope of my Internet presence to offer. Shoes the antivirus program 360 total security a virus file, that's not the way! Try it and trusted it by the antivirus program.
Screenlayout (only in German):
Example für 80, 40 and 20 m band
Here you can download this nice program: DO4MAT- KWSINUS04
Sorry but the charts description is (first) only in German.
Chart special for 2m and 70cm bands
If you have studied the charts please think about, that the end of wire is left on the charts and the antenna feet point is on the right side. Now it's very simple to find the ideal point for your frequencies where the impedance is the same like your cable or transformer. A following tuner must not have a hard job.
Visitors since 06.07.2010