Cage

This is a vertical built up of sixteen basic wires repeated to construct the array of radials and the skeleton of a closed cylinder. Basically this is the model for a thick, solid radiator. The EZNEC design file is set for a real high accuracy ground (the radials are slightly above ground level).
This particular view is to aid in presenting the source on the feed point that separates the main element from the radial system.
This is the SWR response for the slightly taller than 4 Meter structure. The obvious optimization was for a short radiator that also presented a wide match. As this design starts at 20M (for a useful application), the 4 Meter height is not far off from the standard quarterwave. Being thick, it is shorter, but the advantage is with 4 bands that follow.
However, there is no notable gain in actual launch characteristics. As the graphics may be difficult to observe, use your bowser to "view the image" which is at a far better resolution than viewed here. This is true of all the images I publish.