[Antennas] Modeling Multiple Antennae Fed From a Single Point

[Terry Conboy]

Tom,

One way to do this is to make sure that the inverted vees are slightly 
separated (so that none of the wires occupy the same space).  Then place 
your source (type I or V only) on the shortest (highest frequency) 
inverted vee.  Then use a short (e.g. 0.001 foot) transmission line to 
connect the feed-points together.  Since the EZNEC transmission lines 
are imaginary (or virtual), they don't have to be any specific length.  
This avoids having common wires and also wires meeting at very small 
angles, which can affect model accuracy.

Note that for closely spaced wires, the overall lengths for the higher 
bands are around 492/f, while the lowest band is roughly 468/f.

I'm attaching a three-band sample (which may not make it to the list).

73, Terry N6RY

On 2012-02-08 8:53 PM, n5ge at n5ge.com wrote:
> I'm trying to model something that I have done a lot over the years using
> EZNEC+5, but the results don't seem to me to make sense.
>
> Feeding multiple inverted vees from the same feed point is a good way to save
> space and I've been doing it for years, but when I model it with EZNEC I can't
> find a way to connect a source to the point where all of the wires join at the
> top.  I have tried feeding a 1 foot wire that is perpendicular to the junction
> of the wires, but that doesn't work either...
>
> Does anyone know what I should do to properly put a source at the junction of
> the wires?
>
> 73,
> Tom
> N5GE
>