Gem, or Junk?

I've been thinking a lot recently about how best to continue 6m operations.  With plenty of solar activity going on now, and the potential for 6m aurora, this isn't a decision I can put off much longer!

If I want a beam, I will almost certainly have to build one, because the present requirement is for a portable antenna that will dismantle and fit in a car without lots of swearing!

I was then idly looking at MMANA-GAL's models, and came across the 'Sky Door' antenna.  When I turned it on its side, to vertical polarisation, and placed the antenna on a virtual beach in the model, the output was, well, almost unbelievable!  

Pattern of vertically polarised radiation over perfect ground.

The antenna model, with horizontal (blue) and vertical (red) currents shown.

What do you think?  It doesn't look very probable that such a simple loop with a capacitor to match it up could really produce 11dBi gain, even at the coast.  If it's correct, then this is a far preferable option in every respect to a Yagi or other beam. 

But I've never had much cause to doubt the output of this software, so I've already got some 6mm aluminium tube on the way.  Whilst this is possibly not necessary, where it could be an all-wire antenna, both the model and the build on the web site does use tube, so I decided to try that first.

The best reference I could find to a real build of this antenna is found here, in German.  An appeal for any real-world experience on the UK 6 metre Group Facebook page produced no comments.  Even if someone had built it, it's very unlikely they would have taken it to the beach!