× The model behind the picture These surfaces come from calculated NEC-2 far-field patterns, not generated illustrations. Colour is total gain in dBi, referred to accepted antenna power. Both polarisations are included.
20 m copper radiator; maximum height 14 m. Sloper: eastern end at 14 m, western feedpoint at 1 m. Horizontal span 15.2 m. Flat top: all 20 m horizontal at 14 m, along east–west. Inverted L: feed at 1 m, vertical rise 13 m, then 7 m horizontally east. Average homogeneous ground: relative permittivity 13, conductivity 0.005 S/m. 2 m return conductor approximates coax exterior ending at an ideal choke. It runs north for the sloper, south for the L, and down for the flat top. Assumed 0.65 µH lossless coil about 1.5 m along the radiator; actual coil unmeasured. No transformer/mismatch/coil losses, buildings, fences, mast or ionospheric propagation. Radius is relative field amplitude, normalised separately for each antenna and band. Colour uses one common absolute scale. The globe is a geographic orientation aid. The bubble's size relative to Earth is arbitrary.
Best at 10° means the strongest direction anywhere around the antenna at that elevation. The peak and low-angle figures may refer to different bearings. Point at the surface to inspect a specific direction.
The displayed surface uses 2° elevation / 4° azimuth samples; the original calculation used 1° / 2°. Segment-convergence checks changed peak and low-angle gain by about 0.1 dB at 7.1 and 28.4 MHz. Approximate location: Wallington, UK.
Canvas-rendered 3D geometry with Natural Earth land outlines (public domain). No WebGL required. All code, land outlines and pattern data are bundled; no network requests or tracking.
× Put this globe in your post Host the supplied rf-globe.html on your own web hosting. In WordPress, add a Custom HTML block containing an iframe pointing to that file.
<iframe src="YOUR-HOSTED-FILE-URL?embed=1"
title="M7XOM interactive RF globe"
width="100%" height="980"
style="border:0;border-radius:12px"
loading="lazy" allow="fullscreen">
</iframe> The standalone HTML works offline. WordPress may reject HTML-file uploads or strip iframes depending on permissions. Host the file through your hosting file manager, or another static host. Private review links require sign-in and are not suitable as a public blog embed.