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Help with 2xFF6 + DAR

4K views 4 replies 2 participants last post by  holl_ands 
#1 ·
I'm learning 4NEC2 at this point and thus lack the ability yet to run the optimization of an FF6 with a double angle reflector, but think it may prove to be my antenna of choice.

I would like to "borrow" the double angle reflector from the FF4 and stretch it for the FF6. Then optimize the FF6 before investigating a horizontal pair with a Holl_ands Horizontal Harness.

Anyone else intrigued?

FYI. My TV Fool
 
#2 · (Edited)
FF4 without Reflector provides UHF Raw Gain = 9.7 to 12.6 dBi:
UHF Free-Form 4-Bay Bowtie - NO Refl
FF4 with Optimized Double Angle Reflector provides UHF Raw Gain = 14.0 to 15.5 dBi:
UHF Free-Form 4-Bay + DblAnglRefl - OPT

So Optimized Double Angle Reflector provided an improvement of about 4.3 to 2.9 dB.

Horizontally Stacked FF4's (aka H-FF8) provides UHF Raw Gain = 16.9 to 20.1 to 19.8 dB [35-in]
or UHF Raw Gain = 17.3 to 19.6 to 19.4 dBi [51-in Stacking Distance between Center of each 4-Bay]
Horiz Stack 2xFF4 + DAR + HHH

and Vertically Stacked FF4's (aka V-FF8) provides UHF Raw Gain = 17.5 to 19.9 dBi:
Vert-Stack FF4 + DoubleAngleRefl.

So Horizontally Stacking FF4's improves Gain by about 3.0-4.5 dB.
And Vertically Stacking FF4's improves Gain by about 3.5-4.4 dB.

===================================================
FF6 without Reflector provides UHF Raw Gain = 11.0 to 14.5 dBi:
UHF Vertical 6-Bay Bowtie - NO Refl

So FF6 WITH Double Angle Reflector "probably" increases Gain by ABOUT 3.5 dB,
hence we should expect UHF Raw Gain ~ 14.5 to 18.0 dBi (more or less).

Horizontal or Vertical Stacking FF6's "probably" adds ABOUT 4 dB more: UHF Raw Gain ~ 18.5 to 22.0 dBi.

===================================================
So FF6's MAY only provide an improvement of perhaps 1-2 dB versus FF4's....but if you insist....

Following the established patterns, it's tedious but fairly straight-forward to add more HEIGHT to the Variable Double Angle Reflector (V-DAR) Model so that it extends 6-in beyond the FF6 (preferably...could shrink to 4-in if necessary). Perhaps you want to start with the non-Stacked FF6 and add the DAR....it will end up being essentially the SAME in the Stacked version(s)....which is more complicated by incorporating the Stacking Offset....esp. in the Horizontal Stack version.

If YOU modify the STACKED FF4 DAR 4nec2 File, by copy/paste of two FF6's to replace FF4's and extend HEIGHT of the two DARs, I'll run it on one of my computers...AFTER the current heat wave breaks in a few days....I don't have A/C. The Optimization Runs will take AT LEAST a WEEK....for EACH TRIAL...and it usuallly takes at least a few runs to get it right....
 
#3 ·
I have the first .nec file done for a Horiz Stack 2xFF6 + DAR + HHH with 51" spacing.

I only added 6" to the top and bottom of the reflectors for an unfolded size of 60" H x 36" W, with the same 2x2" Grid.
I can add extra height as time permits since this only gives a little less than 4" of coverage to the outer wiskers.

H-Stack51_FF6_VDAR_60x36_HHH.nec is attached in .doc format

Keep in mind there is NO OPTIMIZATION done to the design. The wisker angles are borrowed and extrapolated from the FF4.

Here is a link: https://dl.dropboxusercontent.com/u/12026213/H-Stack51_FF6_VDAR_60x36_HHH.nec.doc
 
#5 ·
UHF FF6 (Free-Form 6-Bay) with VDAR (60"Hx36"W) and HHH (Holl_ands Horizontal Harness):

Well....it took quite a bit more than a week due to lost Run Time after a few forced Restarts.....and demise of my 6-Processor Chip when I decided to brush out the accumulated DUST while it was powered down....fortunately, I still had my old 3-Processor Chip to swap in.

Uploaded RESULTS are found here:
Horiz-Stack 2xFF6 + VDAR + HHH

Note that Inner-Most Bowties are Swept slightly BACK, whereas others are Swept Forward.
UHF Raw Gain = 17.7 to 19.5 to 18.9 to 19.6 dBi, F/B & F/R Ratio Minimum = 14.9 dB and
SWR (300-ohms) Under 2.2. [Raw Gain = 19.0 dBi +/- 0.6 dB, except 17.7 dBi at 470 MHz.]







 
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