Topband: FCP Question

[Richard (Rick) Karlquist]

On 1/9/2021 3:22 AM, Guy Olinger K2AV wrote:
> Hi Rick,
> 
> An answer to Rick and some number of others with inquiries off reflector....
> 

> Those with EZNEC V5 or V6, including the demo version, can find the help
> reference by starting EZNEC (it's identical in V4/5/6). Click on "Help" in
> the menu bar on the main window. Click on "Contents". In the User Manual
> window, click on "Search" in the Contents-Index-Search tab row. In the "to
> find:" space, type in "closely spaced wires"  without the quotes. Click on
> the "List Topics" button.  In the topic list, double click "Closely Spaced
> Wires".

Excellent navigation!  I found it easily.  I will quote the relevant
text from it below:

-------------------------------------------------------------------------

Closely Spaced Wires

When modeling parallel or nearly parallel wires which are closely 
spaced, it can be very important to align the segment junctions. That 
is, they should be directly across from each other. This is particularly 
true if the segment length is greater than the wire spacing. As the 
segment length gets shorter compared to the wire spacing, this 
requirement becomes less important. When segment junctions are 
misaligned but need to be aligned, results can change dramatically as 
segmentation is changed.

The easiest way to assure that aligned parallel wires have aligned 
segment junctions is to give the wires identical lengths and numbers of 
segments. If the wires are staggered or different lengths, break them 
into more wires. Make the portions of the wires which are directly 
across from each other into separate wires of equal length and number of 
segments. An example of this technique is shown below, where the long 
wire of a J-pole antenna was broken into two wires. Wire 4 is made the 
same length and given the same number of segments as parallel wire 6. 
The upper wire is segmented to make its segment length approximately 
equal to the segment length on wire 4. (This is a close up view – some 
of the long wire, and its number, aren't shown.)

------------------------------------------------------------------------

So I was indeed clueless, but no more.  Basically, all I need to do
is align the segments; who knew?  Certainly isn't obvious.  Now I get 
it.  Very clear writing by Roy, as usual.  The J-pole example is
perfect.

73

Rick N6RK