I note the color bar chart x & y axis were written in a non-English language, where were these "tests" performed?
The web site is a .cz site, which would indicate the Czech Republic. Also if you put "Frekvence" into the Google Translate site it will auto-dectect the language to be "Czech" as well. While the tests could've been done in Santa Monica, CA, odds are that there were done in the Czech Republic.
It does seam interesting that they're performing antenna comparisons (frequency vs signal strength) and have a HPN-30118 filter attached (look at the antenna switch picture). Their chart shows a very high signal around 88 MHz, which is in the area that's filtered, which could be why they selected that particular filter. They also feed each antenna with a different sized coax, which could result in different levels of loss and favor one antenna over another. It would be nice to know which antenna was attached to which.
Their "methodology" doesn't sound very scientific either since the signal strength could easily vary as the test is done (say a close station on a simplex channel is on and is answered by a distant station while the switch is moved to another antenna). You'd think that a constant signal strength from a signal generator (in a shielded room) would provide a more accurate test.