[Antennaware] Yagi element capacity hat end loading

[David Gould]

I have a very small back garden so I am limited in the width of 
antenna I can erect.  I want to try and do better than a minibeam.

I am currently using a Cobwebb antenna which is a set of 5 nested 
dipoles for HF bent into a square.  For what it is it works quite 
well, but I want to do better.  I know it is not ideal, but I am 
considering a 2 or 3 element trap yagi, but even with the loading 
coils (yuck!) it is still too wide.  So I am considering trying to 
shorten the elements (particularly the reflector) by replacing the 
outer tips (beyond the trap) with a shorter tip with capacity hat end loading.

I have modelled this in EZNEC for a simple 20m dipole (no traps) and 
have got a feel for the cap hat sizes needed to shorten the tip by 
varying amounts.

1)  Has anyone tried this before? With what learning?

2)  Is there likely to be a significant difference in effect putting 
the cap hat outside a trap rather than on a straight element?

3)  I am not sure I know how to model a 20/15/10 trap element. Does 
anyone have an EZNEC model of a Mosley TA33jnr or Cushcraft A3S, or 
advice how to build just a trapped element that I can play with?

4) Any other thoughts or advice would be appreciated.

73,
Dave, G3UEG