VK5HW - Antenna Dimensions

Some of my models use formulas to calculate the dimensions of the modelled object. Trying to decipher these, if you would like to build an antenna out of one of these models might or might not be easy. However help is at hand.

NOTE: I'm using the metric system.

I assume that you have 4nec2 open and a model loaded.

In the GEOMETRY (F3) Window, select View from the toolbar.

Pic: 1

In the View drop down Window select SYmbol conversion Shft+Y, or you could simply press the <Shift> <Y> key combo.

Pic: 2

This will bring up, either NotePad or WordPad, in my case WordPad, which displays the calculated values for the SYmbols used.

Pic: 3

Pic: 4

The highlighted section in Figure 3 shows the SYmbol D, the formula and the result for the formula. In this case the speed of light (C) divided by the frequency (F) multiplied by the velocity factor (VF) and then divided by 4. After the equal sign (=) you'll see the result in meter, 2.76.......

You can correlate the SYmbols if you open the 4nec editor and check for the SYmbols under the Symbols tab.

Using SYmbols you don't have to do the math to calculate the antenna. All you have to do is change the frequency (SYmbol F, F=28.5) for the band you'd like to use the antenna on, and maybe the height of the antenna (SYmbol H, H=10). So, this model can be quite easily changed to any other band or height or spacing between the elements etc. .

The NEC file can be found under my Files area.

' hope this helps.