FF4 vs M4 - Canadian TV, Computing and Home Theatre Forums

 
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post #1 of 2 (permalink) Old 2016-10-12, 01:00 PM Thread Starter
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Join Date: Mar 2016
Location: sainte-marthe-sur-le-lac, QC (Canada)
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FF4 vs M4

Hi all,

I was reading some posts on this forum about FF4 antenna. My first question: what is a FF4 (free form 4 bay)? The reason I'm asking is because some people have compared it to Mclapp's M4. How is FF4 any different? I also heard it might be better than M4? I'm using a m4 (9"x 8.5") with bowtie's 12AWG ceiling tie wire and 14 AWG copper for phase lines. Using 1" PVC (almost 1.25") and phase lines are swirling around the tube. I'm very happy with the M4 and gives out excellent results.

The FF4 phase lines are 1.25" apart also? Any dimensions for the "V's" that are particular to this model?

thanks.
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post #2 of 2 (permalink) Old 2016-10-12, 07:02 PM
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My FF4 was designed (using nikiml's Python Optimization Scripts) wherein ALL of the various Dimensions were independent VARIABLES. Unlike the M4, the Inner and Outer Bowties were allowed to have DIFFERENT Whisker Lengths, Tine Separations, Forward Sweep and INNER-INNER Bowtie Separation was allowed to be DIFFERENT than the INNER-OUTER Bowtie Separation. Because the FF4 is somewhat TALLER, so is the Double Angled Reflector. Hence the Design can be "Stagger Tuned" [like old Wideband IF Transformers] to provide Higher Gain and a smoother Frequency Response Curve with much less LOSS of GAIN in the Lower end of the UHF Band:
UHF 4-Bay Bowties with Reflector - ImageEvent

Photos of various user's DIY FF4's are included in fol. post:
Best DIY for Cottage Near Barrie, ON?
Also provides links to STACKED FF4's, where I INTENTIONALLY offset them to AVOID having ALL Bowties in a NULL when Ground Bounce Multipath results in NULL Patterns that vary with Height.

My FF6 took this one step further, Optimizing the Design for a 6-Bay Bowtie [if you can build a DIY 4-Bay, it's only a bit more work to build a 6-Bay]. Note the High Gain and FLAT Frequency Response:
UHF Vertical 6-Bay Bowtie with VDAR

Unfortunately, there was some sort of Phase/Amplitude NULLING taking place when extended to an 8-Bay or 10-Bay Design....so it is better to STACK a pair of FF4's or FF6's, as shown in the fol. Comparison Charts:




Antenna Simulations, Overload Calculations, etc: http://imageevent.com/holl_ands

Last edited by holl_ands; 2016-10-12 at 09:16 PM.
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