Hi Lasser
Can you post the .nec file that you are going to use, including your scaling? I'm somewhat new to this as well, so there may be better ways to do things, than what I use. You can post your .nec file by opening it in a Text editor. Select the entire file, and select "copy". Then switch to this site. At the bottom, below the quick reply window, select "Go Advanced". At the top of the window, select the "#" icon, and it will add two "CODE" symbols to your reply. Put the cursor between the two brackets, between the two "code]". Right button on mouse to bring up menu. Select "paste" should insert your .nec file between the two bracketed "code]"'s. Select "Preview Post", from below window, will show you what your post will look like, before you "submit Reply". It will be easier to see what you are working with, if we can see your .nec file.
I think figured out how to re-scale this antenna for max gain at 605 mhz.
It looks like the UHF FF6 Vertical 6-Bay Bowtie - NO Refl antenna might be a good choice. I may be doing things the hard way, but I've found that scaling the .nec file with the "custom factor" function isn't always the best way. It will scale the size of the elements, as well as the dimensions, and this can affect the results. Maybe someone else can tell us how they scale antennas. What I've found that works for me, is to create a Scale factor variable, and adding it to each variable, in the geometry page. I don't add the scale factor variable to the radius column, so my elements retain their dimensions. When I scaled the UHF FF6 Vertical 6-Bay Bowtie - NO Refl antenna, it found that the SWR became excessive. Narrowing the "FeedSep" feed line separation seems to help.
How do I get a DB per frequency graph in 4nec?
Also how do I get the swr, and Azimuthal Pattern graphs?
I'm going to include a .nec file, of my first attempt to scale the FF6 antenna. I don't understand all of the variables in the .nec file, but I've learned that the code near the bottom, after the "LD" line affect the display of SWR, Gain, and impedance. Try running my .nec file, and it should bring up a "line chart" window. In the upper right corner, you can select SWR, Gain, or impedance charts. I also get a window that displays the horizontal reception pattern. Select that window, and use the right and left arrows to move through the different frequencies, that you slected in the freq/ground window in the editor. You will also need to learn how the adjust the AGT. When you select run nec, it brings up the generate window. Select "far field pattern". Set the Freq. to the frequency that you are interested in. For a UHF/Hi-VHF antenna, I check at 198mhz and 534mhz(approx half way across each band), and then set it to a number half way between the two results. Then select "expert settings. Then check "Run Average Gain Test" and "Generate" and "OK". When the results come back, look at the left side of the "Main" window, for the AGT result. It should be as close to 1.0 as possible. Most .nec files use a symbol/variable "Rsrc" that affects AGT. Slowly increase the Rsrc variable to increase the AGT and decrease the Rsrc to lower the AGT. The closer the AGT number is to 1.0, the more acurate your Gain results will be.
Code:
CM UHF Free-Form Super-6-Bay, NO Refl, 4nec2 by holl_ands, 11Dec2014
CM BowLength=vrbl, BowSpacing=vrbl, TineSep=vrbl (AWG10 Elements), Hop=1.0-in.
CM NO Reflector. FeedSep=vrbl (AWG10). Ready for Python Optimization, 12 VARIABLES.
CM Top & Bottom HOPs are Mirror Images. PYTHONSEG(13), AGT=1.0, NO Errors or Warnings.
CM
CM D--OPT -s(470,12,22) -t(12,15) --swr-target=2.7
CM D--OPT --target-function=(4*max_ml+16*max_gain_diff)/20
CM D--OPT --auto-segmentation=13 --char-impedance=300 --num-cores=7
CM D--EVAL --auto-segmentation=13 --char-impedance=300 --num-cores=7
CM D--EVAL -s(174,6,8) -s(470,12,29) --publish
CM SOURCE Wire Radius, Adjusted for AGT=1.0: UHF=0.0173, HiVHF=0.0159
CM Radius (in inches) of BOWTIE elements:
CM Radius (in inches) of FEEDLINE wires
CM Separation at Crossover
CM Conductivity (Copper=3.0e7, Alum=2.0e7, StainlessSteel=1.67e7)
CM
CM Distance between the centers of the two INNER bowties:
CM From center of INNER bowtie to center of OUTER bowtie:
CM From center of OUTER bowtie to center of EXTERIOR bowtie:
CM INNER Bow Whisker Length (lose some in bend):
CM OUTER Bow Whisker Length (lose some in bend):
CM EXTERIOR Bow Whisker Length (lose some in bend):
CM INNER Bow Forward Sweep distance at tip of the whisker:
CM OUTER Bow Forward Sweep distance at tip of the whisker:
CM EXTERIOR Bow Forward Sweep distance at tip of the whisker:
CM INNER Bow Tine Separation:
CM OUTER Bow Tine Separation:
CM EXTERIOR Bow Tine Separation:
CM Separation between two FEEDLINE wires: [CONSTRAINT: TRY ALL THE SAME.]
CM From center of Feedline Cross-Over to center of OUTER Bowtie:
CM From center of Feedline Cross-Over to center of EXTERIOR Bowtie:
CM Bowtie Separation in FRONT of Reflector (which is at X=0): [NOT USED HERE]
CM
CM Calculated from above INPUT Values:
CM
CM # segs X1 Y1 Z1 X2 Y2 Z2 radius
CM SIMULATED SOURCE WIRE:
CM INNER BOWTIES:
CM OUTER BOWTIES:
CM EXTERIOR BOWTIES:
CM OUTER CROSS-OVER FEEDLINES:
CM EXTERIOR CROSS-OVER FEEDLINES:
CM INNER FEEDLINES:
CM
CM
CM FR Freq Sweep choices in order of increasing calculation time (fm holl_ands):
CM FR 0 0 0 0 470 0
CM FR 0 39 0 0 470 6
CM FR 0 77 0 0 470 3
CM FR 0 153 0 0 470 1.5
CM FR 0 71 0 0 300 10
CM FR Hi-VHF choices:
CM FR 0 15 0 0 174 3
CM FR 0 29 0 0 174 1.5
CM FR 0 43 0 0 174 1
CM FR 0 26 0 0 150 6
CM FR Lo-VHF choices:
CM FR 0 19 0 0 54 3
CM FR 0 35 0 0 54 1
CM FR 0 36 0 0 75 1
CM RP choices in order of increasing calculation time:
CM RP 0 1 1 1510 90 0 1 1 0 0
CM RP 0 1 37 1510 90 0 1 5 0 0
CM RP 0 73 1 1510 90 0 5 1 0 0
CM RP 0 73 73 1510 90 0 5 5 0 0
CM RP 0 285 73 1510 90 0 5 5 0 0
CE
SY Scale=1.15
SY sc=Scale
SY Rsrc=0.041 'Rsrc(200)=0.042 Rsrc(533)=0.04
SY Rbow=0.051
SY Rfeed=0.051
SY Hop=1.0
SY Cond=3e+07
SY ZBowII=13.07315 '7, 40
SY ZBowOI=11.1262 '7, 40
SY ZBowOE=9.019928 '7, 40
SY BowLeni=11.63122 '7, 40
SY BowLeno=7.710528 '7, 40
SY BowLenE=7.818797 '7, 40
SY BowSwpi=0
SY BowSwpo=0
SY BowSwpE=0
SY TineSepi=7.569343 '2, 10
SY TineSepo=5.604077 '2, 10
SY TineSepE=3.572662 '2, 10
SY FeedSep=1.227 '1.227
SY ZCross=2.182639 '1.25, 6
SY ZCrossE=3.010845 '1.25, 6
SY RS=0.0
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 ZBowExt=ZBowII/2+ZBowOI+ZBowOE 'From antenna center to center of EXTERIOR bowtie
SY Z1=ZBowOut+TineSepo/2
SY Z2=ZBowOut
SY Z3=ZBowOut-TineSepo/2
SY Z4=ZBowOut-ZCross+0.875
SY Z5=ZBowOut-ZCross
SY Z6=ZBowOut-ZCross-0.875
SY Z7=ZBowInr+TineSepi/2
SY Z8=ZBowInr
SY Z9=ZBowInr-TineSepi/2
SY Z11=ZBowExt+TineSepE/2
SY Z12=ZBowExt
SY Z13=ZBowExt+-TineSepE/2
SY Z14=ZBowExt-ZCrossE+0.875
SY Z15=ZBowExt-ZCrossE
SY Z16=ZBowExt-ZCrossE-0.875
SY YBowInr=FeedSep/2+(BowLeni^2-(TineSepi/2)^2-BowSwpi^2)^0.5 'Ymax for Inner Bowties
SY YBowOut=FeedSep/2+(BowLeno^2-(TineSepo/2)^2-BowSwpo^2)^0.5 'Ymax for Outer Bowties
SY YBowExt=FeedSep/2+(BowLenE^2-(TineSepE/2)^2-BowSwpE^2)^0.5 'Ymax for Exterior Bowties
GW 1 3 RS*sc (-FeedSep/2)*sc 0 RS*sc (FeedSep/2)*sc 0 Rsrc
GW 2 12 (BowSwpi+RS)*sc (YBowInr)*sc Z7*sc RS*sc (FeedSep/2)*sc Z8*sc Rbow
GW 3 12 (BowSwpi+RS)*sc (YBowInr)*sc Z9*sc RS*sc (FeedSep/2)*sc Z8*sc Rbow
GW 4 12 RS*sc (-FeedSep/2)*sc Z8*sc (BowSwpi+RS)*sc (-YBowInr)*sc Z7*sc Rbow
GW 5 12 RS*sc (-FeedSep/2)*sc Z8*sc (BowSwpi+RS)*sc (-YBowInr)*sc Z9*sc Rbow
GW 6 12 (BowSwpi+RS)*sc (YBowInr)*sc -Z7*sc RS*sc (FeedSep/2)*sc -Z8*sc Rbow
GW 7 12 (BowSwpi+RS)*sc (YBowInr)*sc -Z9*sc RS*sc (FeedSep/2)*sc -Z8*sc Rbow
GW 8 12 RS*sc (-FeedSep/2)*sc -Z8*sc (BowSwpi+RS)*sc (-YBowInr)*sc -Z7*sc Rbow
GW 9 12 RS*sc (-FeedSep/2)*sc -Z8*sc (BowSwpi+RS)*sc (-YBowInr)*sc -Z9*sc Rbow
GW 10 8 (BowSwpo+RS)*sc (YBowOut)*sc Z1*sc RS*sc (FeedSep/2)*sc Z2*sc Rbow
GW 11 8 (BowSwpo+RS)*sc (YBowOut)*sc Z3*sc RS*sc (FeedSep/2)*sc Z2*sc Rbow
GW 12 8 RS*sc (-FeedSep/2)*sc Z2*sc (BowSwpo+RS)*sc (-YBowOut)*sc Z1*sc Rbow
GW 13 8 RS*sc (-FeedSep/2)*sc Z2*sc (BowSwpo+RS)*sc (-YBowOut)*sc Z3*sc Rbow
GW 14 8 (BowSwpo+RS)*sc (YBowOut)*sc -Z1*sc RS*sc (FeedSep/2)*sc -Z2*sc Rbow
GW 15 8 (BowSwpo+RS)*sc (YBowOut)*sc -Z3*sc RS*sc (FeedSep/2)*sc -Z2*sc Rbow
GW 16 8 RS*sc (-FeedSep/2)*sc -Z2*sc (BowSwpo+RS)*sc (-YBowOut)*sc -Z1*sc Rbow
GW 17 8 RS*sc (-FeedSep/2)*sc -Z2*sc (BowSwpo+RS)*sc (-YBowOut)*sc -Z3*sc Rbow
GW 40 8 (BowSwpE+RS)*sc (YBowExt)*sc Z11*sc RS*sc (FeedSep/2)*sc Z12*sc Rbow
GW 41 8 (BowSwpE+RS)*sc (YBowExt)*sc Z13*sc RS*sc (FeedSep/2)*sc Z12*sc Rbow
GW 42 8 RS*sc (-FeedSep/2)*sc Z12*sc (BowSwpE+RS)*sc (-YBowExt)*sc Z11*sc Rbow
GW 43 8 RS*sc (-FeedSep/2)*sc Z12*sc (BowSwpE+RS)*sc (-YBowExt)*sc Z13*sc Rbow
GW 44 8 (BowSwpE+RS)*sc (YBowExt)*sc -Z11*sc RS*sc (FeedSep/2)*sc -Z12*sc Rbow
GW 45 8 (BowSwpE+RS)*sc (YBowExt)*sc -Z13*sc RS*sc (FeedSep/2)*sc -Z12*sc Rbow
GW 46 8 RS*sc (-FeedSep/2)*sc -Z12*sc (BowSwpE+RS)*sc (-YBowExt)*sc -Z11*sc Rbow
GW 47 8 RS*sc (-FeedSep/2)*sc -Z12*sc (BowSwpE+RS)*sc (-YBowExt)*sc -Z13*sc Rbow
GW 18 1 RS*sc (FeedSep/2)*sc Z2*sc RS*sc (FeedSep/2)*sc Z4*sc Rfeed
GW 19 1 RS*sc (-FeedSep/2)*sc Z2*sc RS*sc (-FeedSep/2)*sc Z4*sc Rfeed
GW 20 8 RS*sc (FeedSep/2)*sc Z6*sc RS*sc (FeedSep/2)*sc Z8*sc Rfeed
GW 21 8 RS*sc (-FeedSep/2)*sc Z6*sc RS*sc (-FeedSep/2)*sc Z8*sc Rfeed
GW 22 2 RS*sc (-FeedSep/2)*sc Z6*sc (Hop/2+RS)*sc 0 Z5*sc Rfeed
GW 23 2 RS*sc (FeedSep/2)*sc Z4*sc (Hop/2+RS)*sc 0 Z5*sc Rfeed
GW 24 2 RS*sc (FeedSep/2)*sc Z6*sc (-Hop/2+RS)*sc 0 Z5*sc Rfeed
GW 25 2 RS*sc (-FeedSep/2)*sc Z4*sc (-Hop/2+RS)*sc 0 Z5*sc Rfeed
GW 26 1 RS*sc (FeedSep/2)*sc -Z2*sc RS*sc (FeedSep/2)*sc -Z4*sc Rfeed
GW 27 1 RS*sc (-FeedSep/2)*sc -Z2*sc RS*sc (-FeedSep/2)*sc -Z4*sc Rfeed
GW 28 8 RS*sc (FeedSep/2)*sc -Z6*sc RS*sc (FeedSep/2)*sc -Z8*sc Rfeed
GW 29 8 RS*sc (-FeedSep/2)*sc -Z6*sc RS*sc (-FeedSep/2)*sc -Z8*sc Rfeed
GW 30 2 RS*sc (-FeedSep/2)*sc -Z6*sc (-Hop/2+RS)*sc 0 -Z5*sc Rfeed
GW 31 2 RS*sc (FeedSep/2)*sc -Z4*sc (-Hop/2+RS)*sc 0 -Z5*sc Rfeed
GW 32 2 RS*sc (FeedSep/2)*sc -Z6*sc (Hop/2+RS)*sc 0 -Z5*sc Rfeed
GW 33 2 RS*sc (-FeedSep/2)*sc -Z4*sc (Hop/2+RS)*sc 0 -Z5*sc Rfeed
GW 48 2 RS*sc (FeedSep/2)*sc Z12*sc RS*sc (FeedSep/2)*sc Z14*sc Rfeed
GW 49 2 RS*sc (-FeedSep/2)*sc Z12*sc RS*sc (-FeedSep/2)*sc Z14*sc Rfeed
GW 50 5 RS*sc (FeedSep/2)*sc Z16*sc RS*sc (FeedSep/2)*sc Z2*sc Rfeed
GW 51 5 RS*sc (-FeedSep/2)*sc Z16*sc RS*sc (-FeedSep/2)*sc Z2*sc Rfeed
GW 52 2 RS*sc (-FeedSep/2)*sc Z16*sc (Hop/2+RS)*sc 0 Z15*sc Rfeed
GW 53 2 RS*sc (FeedSep/2)*sc Z14*sc (Hop/2+RS)*sc 0 Z15*sc Rfeed
GW 54 2 RS*sc (FeedSep/2)*sc Z16*sc (-Hop/2+RS)*sc 0 Z15*sc Rfeed
GW 55 2 RS*sc (-FeedSep/2)*sc Z14*sc (-Hop/2+RS)*sc 0 Z15*sc Rfeed
GW 56 2 RS*sc (FeedSep/2)*sc -Z12*sc RS*sc (FeedSep/2)*sc -Z14*sc Rfeed
GW 57 2 RS*sc (-FeedSep/2)*sc -Z12*sc RS*sc (-FeedSep/2)*sc -Z14*sc Rfeed
GW 58 5 RS*sc (FeedSep/2)*sc -Z16*sc RS*sc (FeedSep/2)*sc -Z2*sc Rfeed
GW 59 5 RS*sc (-FeedSep/2)*sc -Z16*sc RS*sc (-FeedSep/2)*sc -Z2*sc Rfeed
GW 60 2 RS*sc (-FeedSep/2)*sc -Z16*sc (-Hop/2+RS)*sc 0 -Z15*sc Rfeed
GW 61 2 RS*sc (FeedSep/2)*sc -Z14*sc (-Hop/2+RS)*sc 0 -Z15*sc Rfeed
GW 62 2 RS*sc (FeedSep/2)*sc -Z16*sc (Hop/2+RS)*sc 0 -Z15*sc Rfeed
GW 63 2 RS*sc (-FeedSep/2)*sc -Z14*sc (Hop/2+RS)*sc 0 -Z15*sc Rfeed
GW 34 7 RS*sc (FeedSep/2)*sc Z8*sc RS*sc (FeedSep/2)*sc 0 Rfeed
GW 35 7 RS*sc (-FeedSep/2)*sc Z8*sc RS*sc (-FeedSep/2)*sc 0 Rfeed
GW 36 7 RS*sc (FeedSep/2)*sc -Z8*sc RS*sc (FeedSep/2)*sc 0 Rfeed
GW 37 7 RS*sc (-FeedSep/2)*sc -Z8*sc RS*sc (-FeedSep/2)*sc 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 'SOURCE on GW1
FR 0 38 0 0 174 12
RP 0 1 73 1510 90 0 1 5 0 0
EN
You can see, in the Symbols, that I rescaled the antenna by 1.15. This moves the max gain closer to 606mhz. As you can see, I narrowed the feed seperation, and this lowered the SWR considerably. Let me know if your able to generate results in 4nec2.. I'll try to look at your .nec file, if you can post it. Maybe some of the experts can give us both some suggestions.
Lawrence