As promised yesterday, I've attached the mentioned plot.
A couple of additional notes:
1) I added black vertical lines to denote the boundaries of the current high HF and UHF bands.
2) Low VHF reception was not a factor in this data collection effort.
3) The RCA751R was purchased at a local Menard's in late 2015.
4) The RCA 7511 and 705Z were purchased from a local Walmart less than a month ago.
5) The Winegard HD7000R was purchased from an online seller this spring. It is the newest (known) version that includes the low-VHF conversion kit which was not installed for this testing.
6. The GE 30741 was purchased about a year ago at a local Walmart.
7. The CM3010 was purchased directly from CM's web store last summer. COMMENT: This antenna fared so poorly against the rest of the pack that I suspect that it may have a faulty balun. The alternative interpretation is obvious.
8. The identical physical layout, cabling, test equipment configuration, and data collection procedures were used for each antenna to the best of my knowledge and ability.
9. Boresite reception as a basis for a relative antenna performance comparison is only one of the possible tests that can be performed to characterize any given antenna. Polar patterns are probably a more instructive characterization as they identify the additional parameters of F/B ratio, F/R ratio, beam width, as well as major and minor lobes, if any. They are not included in this posting for various reasons including several deficiencies that I identified post-testing and I'd prefer not to have to address.
Observations:
By virtue of it's UHF reflectors, the RCA705Z offered the best UHF performance of this cohort. It's VHF performance, however, was hindered by its single folded dipole element when compared to its stablemates. Now, if they tacked that UHF front end onto the VHF section of the 75XX, it would be an interesting combo for close-in work. It also probably would not end up on the shelf at Walmart due to the resulting larger package size, IMHO.
The other two RCAs and the WG (all three are manufactured by WG) are based on the same original design and are all very similar in performance with some observable minor differences. FWIW, it would be my opinion that the casual antenna user would probably never note any difference unless they happened to be right on the edge of reception for a station using a channel where a difference in reception can be discerned from the attached plot. YMMV.
If I think of more comments later, I will append them below this line.
Cheers!