The current ARRL flag was adopted in 1980 based on a design by Ralph Holberg, N4RX. There are 15 horizontal stripes, red and white, and one vertical red stripe at the hoist, all suggesting the stripes of the US and Canadian flags. The horizontal red stripes spell QST in Morse code, a dah stripe being three times as wide as a dit stripe.
QST means 'Information'. When used affirmatively, it means, 'I have information.' When used interrogatively, it means, 'Do you have information?'" It's also the name of the ARRL's magazine.
A more accurate depiction can usually be found at www.arrl.org. Note that the flag's general proportions are those of the official proportions of the U.S. flag, and that the ARRL logo is blue in the flag, not black and yellow (although this coloration is often otherwise used by ARRL, but not in the flag), same as U.S. flag blue, with white figures. The vertical red bar at the staff side comes from the Canadian flag. When the flag was adopted Canada was a division of ARRL but has since become a separate entity. The flag did not change. The horizontal stripes spell out QST in Morse which letters, according to my understanding, mean "This station has information to follow for all amateur stations" and precedes a bulletin of general amateur interest. The stripes are 15 in number and refer to the 15 divisions of ARRL. Hope this information is helpful.
I have in my possession (and can supply a photo of) an ARRL flag where the diamond logo is reversed - a white background with blue symbols.
This is strictly a national United States of American (USA) organization, though there is a definite international flair to HAM Radio. (There's no "political" boundaries when it comes to radio waves...)
Regarding the ARRL flag, as per my father, who is a ham radio operator, the symbol in middle of the logo is a simple electronic schematic representing, top to bottom: antenna, coil, ground.