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Discussion Starter #1
Was shooting for a better 4 bay with good vhf over the entire
Hi-VHF band.

Had no luck with that, but did create a very good flat gain uhf. (4 whiskers, not a hybrid)

Average gain per channel is 12.34 db.

For some one wanting to get the lower channels,
channel 14 (470 mhz) is 11.41 db.



Graphic of the antenna





UHF gain:




Swr:




Have fun building antennas!
 

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I’ve noticed most designs drop off a lot in gain under channel 20. This one definitely doesn’t! Very good.
 

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Discussion Starter #3
Just noticed, that I forgot to include the Nec code.

Simple Flat Uhf Gain 4 Bay Bow Ties Antenna Nec code:

Code:
CM Uhf 4 bay ff4 antenna: 
CM 9 inch bow length
CM UHF Gain: 9.97 to 11.90 to 11.18 db, Swr 4.21 to 1.61
CM VHF Gain: 4.68 to 4.78 db, Swr 2.89 to 1.34 to 3.28 
CM 539 Mhz Auto Segmentation: 23, 201 MHZ autoseg 8
CE
SY Rsrc=0.0202    ' 539 mhz SOURCE wire Radius.
'SY Rsrc=0.0267    '201 mhz SOURCE wire Radius.
SY Rbow=0.0404    'Radius (in inches) of BOWTIE elements
SY Rfeed=0.0254    'FEEDLINE wire Radius (in case they're different)

SY ZBowII=15.58838    ' Distance between the Centers of the two INNER bowties
SY ZBowOI=13.72508    ' From Center of INNER bowtie to Center of OUTER bowtie
SY BowLenI=12.23291    ' Bow Half-Length Inner(plus some in bend) - Assume all SAME
SY BowLenO=8.921283    'Bow Half-Length - Assume all SAME (Reality +/- 0.25+ in)
SY AngleInr=14.8571622    ' Angle = half of the flare Angle in degrees
SY AngleOut=AngleInr    ' Angle = half of the flare Angle in degrees
SY BowSepI= 2 * BowLenI * SIN(AngleInr)        ' INNER Bow Tine Separation - Assume all SAME
SY BowSepO= 2 * BowLenO * SIN(AngleOut)        ' OUTER Bow Tine Separation - Assume all SAME
SY MidWhisker=BowLenO    ' Middle whisker Length
SY MidWhisker2=MidWhisker    ' Middle whisker Length

SY FeedSep=2.099559    'Separation (in inches) between two FEEDLINE wires
SY Hop=1.25    'Separation between Feedlines at Crossover
SY Cond=1.67e7    'Conductivity (Copper=3.0e7, Alum=2.0e7, StainlessSteel=1.67e7)
' Calculated from above INPUT Values:
SY ZBowInr=ZBowII/2    'Distance from antenna center to center of INNER bowtie
SY ZBowOut=ZBowII/2+ZBowOI    'Distance from antenna center to center of OUTER bowtie
SY Z1=ZBowOut+BowSepO/2
SY Z2=ZBowOut
SY Z3=ZBowOut-BowSepO/2
SY Z4=ZBowOut'Very long crossover region
SY Z5=(ZBowII + ZBowOI)/2
SY Z6=ZBowInr'Very long crossover region
SY Z7=ZBowInr+BowSepI/2
SY Z8=ZBowInr
SY Z9=ZBowInr-BowSepI/2
SY YBowInr=FeedSep/2 + BowLenI * COS(AngleInr)' Ymax for Inner Bowties
SY YBowOut=FeedSep/2 + BowLenO * COS(AngleOut)' Ymax for Outer Bowties
SY YBowN=-FeedSep/2
SY YBowP=FeedSep/2
SY YMidWhisker = (FeedSep/2)+(MidWhisker)    'Ymax for Outer Bowties
'  #    segs    X1      Y1    Z1    X2      Y2        Z2    radius
' SIMULATED BALUN SOURCE ON GW1:
GW    1    3    0    YBowN    0    0    YBowP    0    Rsrc
' GW2 Not used
' GW3 Not used
' INNER BOWTIES:
GW    4     7    0    YBowInr    Z7    0    YBowP    Z8    Rbow
GW    5     7    0    YBowInr    Z9    0    YBowP    Z8    Rbow
GW    6     7    0    YBowN    Z8    0    -YBowInr    Z7    Rbow
GW    7     7    0    YBowN    Z8    0    -YBowInr    Z9    Rbow
GW    8     7    0    YBowInr    -Z7    0    YBowP    -Z8    Rbow
GW    9     7    0    YBowInr    -Z9    0    YBowP    -Z8    Rbow
GW    10     7    0    YBowN    -Z8    0    -YBowInr    -Z7    Rbow
GW    11     7    0    YBowN    -Z8    0    -YBowInr    -Z9    Rbow
' OUTER BOWTIES:
GW    12    7    0    YBowOut    Z1    0    YBowP    Z2    Rbow
GW    13    7    0    YBowOut    Z3    0    YBowP    Z2    Rbow
GW    14    7    0    YBowN    Z2    0    -YBowOut    Z1    Rbow
GW    15    7    0    YBowN    Z2    0    -YBowOut    Z3    Rbow
GW    16    7    0    YBowOut    -Z1    0    YBowP    -Z2    Rbow
GW    17    7    0    YBowOut    -Z3    0    YBowP    -Z2    Rbow
GW    18    7    0    YBowN    -Z2    0    -YBowOut    -Z1    Rbow
GW    19    7    0    YBowN    -Z2    0    -YBowOut    -Z3    Rbow
' CROSS-OVER FEEDLINE:
GW    24    5    0    YBowN    Z6    Hop/2    0    Z5    Rfeed
GW    25    5    0    YBowP    Z4    Hop/2    0    Z5    Rfeed
GW    26    5    0    YBowP    Z6    -Hop/2    0    Z5    Rfeed
GW    27    5    0    YBowN    Z4    -Hop/2    0    Z5    Rfeed
GW    32    5    0    YBowN    -Z6    Hop/2    0    -Z5    Rfeed
GW    33    5    0    YBowP    -Z4    Hop/2    0    -Z5    Rfeed
GW    34    5    0    YBowP    -Z6    -Hop/2    0    -Z5    Rfeed
GW    35    5    0    YBowN    -Z4    -Hop/2    0    -Z5    Rfeed
GW    36    4    0    YBowP    Z8    0    YBowP    0    Rfeed
GW    37    4    0    YBowN    Z8    0    YBowN    0    Rfeed
GW    38    4    0    YBowP    -Z8    0    YBowP    0    Rfeed
GW    39    4    0    YBowN    -Z8    0    YBowN    0    Rfeed
GS    0    0    0.0254
GE    0
LD    5    0    0    0    Cond    'Conductivity
GN    -1
EK
EX    0    1    2    0    1    0    0    0    'GW1 is SOURCE wire
FR    0    29    0    0    539    12
RP    0    1    73    1510    90    0    1    5    0    0
EN
 

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I noticed that the impedance match, of your FF4, goes from 100 to 600ohms. Is there any way to get that curve closer to 300ohms? One of my applications has a pretty long cable run, and I'm concerned with the loss, due to impedance mismatch. My work, on a repack of the SuperQuad, keeps the impedance between 200 and 400ohms and averages just 1/2db less actual gain, across the repack, with better SWR. Do you think that you can improve the impedance match, without losing the additional gain?

Are the gain's, that your listing/comparing, raw gain or actual gain?
 

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Discussion Starter #5 (Edited)
Used the 4nec2 optimizer, so that it optimizes for average impedance.

Maybe, if I tell the optimizer to get me the maxiumn impedance in the frequency sweep, instead of
the average impedance, it might flatten the impedance curve.

Maybe that would not affect the gain.

This is a big maybe.

Did you re-scale the SuperQuad to get a repack SuperQuad ?

This antenna uses the same angles in the bow ties, that the SuperQuad uses.

On the question on raw gain or actual gain?

It is raw gain.

The gain listed in the comparison was developed from frequency sweep gain.

Found out, when you choose plot menu, from frequency sweep gain (470-608 mhz,step 1), it gives you the
frequency & gain in notepad.

Did a computer program to find the average gain for each channel.

Then found the average channel gain of the channels.

The program in freebasic is found here:

Freebasic program to find average channel gain
 

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Discussion Starter #6
One thing that can flatten the impedance cure, would be sheet metal rounded bow ties.

If wind load is a factor, one could attach 4 nylon ropes to the tower, or attach it to the metal pipe, just below the antenna.

These ropes would anchor the antenna.

That would take care of the extra wind load.
 

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Discussion Starter #7
Tried frequency sweep max impedance in the optimizer.

No luck!

I am certain that it could be done, but need a better optimizer, with standard
deviation option, to do it.

Do you know there is a loop hole to get around high swr in a antenna.

Example if you have high swr on channel 7, you can make the coax a odd
quarter wavelength long to avoid the swr problem.

As for the consequent degradation to the digital waveform, I believe that is only on
long cable runs.

It is best it is too keep the cable to the pre-amp as short as
possible.

On Swr by holl_ands
 
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