F/B and F/R Ratio specs for Commercial Hi-VHF antennas are only so-so (dBi = dBd + 2.15 dB):
W-G HD-7082P, F/B Ratio > 20 dB on Ch13 with 12.2 dBi Gain (111-in boom)
W-G HD-7080P, F/B Ratio > 18 dB on Ch13 with 13.2 dBi Gain (90-in boom)
W-G HD-8200U, F/B Ratio = 18 dB on Ch13 with 14.2 dBi Gain (168-in boom)
W-G HD-7084P, F/B Ratio = 17 dB on Ch13 with 13.0 dBi Gain (131-in boom)
W-G HD-5030, F/B Ratio = 15 dB on Ch13 with 10.3 dBi Gain (120-in boom)
W-G YA-1713, F/B Ratio = 14 dB on Ch13 with 12.5 dBi Gain (100-in boom)
W-G HD-769xP, F/B Ratio = 14 dB on Ch13 (for any size in the series)
Antennacraft Y10-7-13, F/B Ratio = 16.5 dBi with 11.6 dBi Gain in Hi-VHF band "somewhere" (120-in boom)
Unfortunately, most of the other manufacturers don't bother providing specs anymore.....
Pricey Professional Hi-VHF antennas are quite a bit better:
Wade WL7-13/S, F/B Ratio > 25 dB with 11.5 dBi Gain (96-in boom)
I modeled and compared several DIY Hi-VHF Antennas here:
Comparison charts are included in K6STI results:
DIY K6STI's 5-ELEMENT YAGI:
Optimized for best F/R Ratio on Ch7-13, and has a F/B Ratio that is even higher than
the charted F/R Ratio (see chart below).
Shrinking all sizes by a factor of about 0.94 (seat of pants guestimate, not modeled)
would move the F/R Ratio peak so that it falls on top of Ch13.
DIY 13-ELEMENT YAGI WITH 2 REFLECTORS:
User <kgb> posted a UHF Yagi design, which
has been rescaled for Ch13. However, I was unimpressed by either Gain or F/B numbers:
Perhaps it needs an additional Reflector between the other two to improve F/B Ratio......
DIY ZS6BTE's 14-ELEMENT LPDA:
Exhibited an even higher F/B Ratio (equal to F/R Ratio) on Ch13:
My DIY WEDGE ZIG-ZAG LPDA:
Simple DIY design for attic use also had high F/B and F/R Ratios:
Can null out an undesired channel when it is in nearly the opposite direction
as the desired direction....which is the case for your two Ch13 stations:
I haven't seen any good numbers on how effective this is.
It would be a simple, interesting project for 4nec2 modeling.....