I feel that you are getting too much conflicting info
I worked for 35 years as a TX engineer and was also involved in antenna research which really exposed the crap published by sellers.
The best factual web site that I have seen is
http://www.dj0ip.de/vertical-antenna...band-vertical/
have a look, simple but factual
Our antenna research found that apart from UHF and SHF there was nothing new in practical antenna design since the late 1930's
MM0HDW