• Public Gallery  • Help  
• Join Now!  • Log In  • Feature Tour
 holl_ands | Home > Yagi Antennas > 
HiVHF 9-El FD-Yagi, Stellar Labs 30-2475
Hi-VHF 9-Element Folded Dipole Yagi, including 3 Reflector Rods, MCM Stellar Labs 30-2475,
analyzed using 4nec2.  Initial Dimensions were provided by user [MikeBear].
Analysis revealed that Antenna per MikeBear's Measurements were very close to OPTIMUM,
for the chosen use of Three Reflector Rods....but Repurposing Two RR's as Directors improved
Raw Gain on Ch13 by about 1 dB and F/R Ratio improved several dB on Lower Channels.

Several Versions are presented here [For comparison, completely Re-Optimized 9-El FD-Yagi's
are Analyzed in another Album]:

a) Per MikeBear Measurements with Upper/Lower Reflector Rods 2-in in FRONT of Middle Reflector Rod:

HiVHF Raw Gain = 8.7 to 10.8 dBi, F/B & F/R Ratio = 10.3 to 21.0 to 19.2 to 19.8 dB
[Poor on Low Channels] and SWR (300-ohms) is Under 2.2 (EXCELLENT).

Moving the X and/or Z-Coordinates of the two Upper/Lower Reflector Rods in vicinity of current
locations did NOT significantly improve either Gain, SWR or F/R Ratio.
Boom Length = 59.375-in + Ends.

====================================
b) Analyzed Upper/Lower Reflector Rods Repurposed as Two Additional Directors:
[Requires a Front Boom Extension.]

HiVHF Raw Gain = 8.6 to 12.0 dBi, F/B Ratio = 14.1 dB and SWR (300-ohms) Under 2.2.

Improves Ch13 Gain and F/R Ratio on Lower Channels.  SWR is Excellent.
New Boom Length = 95.7-in + Ends

c) Upper/Lower Reflector Rods were removed to investigate degradation to F/R Ratio
(at expense of Raw Gain).  See below Charts for results.

d) ALL three Reflector Rods were removed to investigate degradation to F/R Ratio
(at expense of Raw Gain).  See below Charts for results.

e) Location of Upper/Lower Reflector Rods relative to Middle Reflector was Re-Optimized,
but there was NO overall improvement when Constrained to be BEHIND the Folded Dipole.

====================================
CORRECTION (14 Dec 2015): This 9-El FD Yagi Analysis replaces Earlier Analysis (8-El FD Yagi)
that was MISSING Director just 2.5-in in front of Folding Dipole [very hard to see in mfr diagram].
There was only a few tenths of dB change in Performance with much lower SWR.
Date(s): 14 Dec 2015. Album by holl_ands. 1 - 34 of 34 Total. 2484 Visits.
Start SlideshowTo order prints and photo-products: 1. Select photos. 2. Click Order. 3. Select products.Select images and click to download to your computer 
Enlarge photo 1
enlarge 56KB, 1024x656
1
HiVHF 9-El FD-Yagi - Stellar Labs 302475
3D View


Enlarge photo 2
enlarge 245KB, 1152x717
2
HiVHF 9-El FD-Yagi - Stellar Labs 302475
Top View
[1 large square = 5 inches]


Enlarge photo 3
enlarge 145KB, 1152x429
3
HiVHF 9-El FD-Yagi - Stellar Labs 302475
Side View
[1 large square = 5 inches]


Enlarge photo 4
enlarge 162KB, 1024x647
4
HiVHF 9-El FD-Yagi - Stellar Labs 302475
HiVHF Raw Gain = 8.7 to 10.8 dBi
HiVHF F/B & F/R Ratio = 10.3 to 21.0 to 19.2 to 19.8 dB


Enlarge photo 5
enlarge 185KB, 1024x647
5
HiVHF 9-El FD-Yagi - Stellar Labs 302475
HiVHF SWR (300-ohms) Under 2.2


Enlarge photo 6
enlarge 225KB, 1024x647
6
HiVHF 9-El FD-Yagi - Stellar Labs 302475
HiVHF Impedance


Enlarge photo 7
enlarge 319KB, 1024x1024
7
HiVHF 9-El FD-Yagi - Stellar Labs 302475
Azimuthal Pattern at 174 MHz


Enlarge photo 8
enlarge 315KB, 1024x1024
8
HiVHF 9-El FD-Yagi - Stellar Labs 302475
Azimuthal Pattern at 198 MHz


Enlarge photo 9
enlarge 321KB, 1024x1024
9
HiVHF 9-El FD-Yagi - Stellar Labs 302475
Azimuthal Pattern at 216 MHz


Enlarge photo 10
enlarge 316KB, 1024x1024
10
HiVHF 9-El FD-Yagi - Stellar Labs 302475
Elevation Pattern at 174 MHz


Enlarge photo 11
enlarge 316KB, 1024x1024
11
HiVHF 9-El FD-Yagi - Stellar Labs 302475
Elevation Pattern at 198 MHz


Enlarge photo 12
enlarge 332KB, 1024x1024
12
HiVHF 9-El FD-Yagi - Stellar Labs 302475
Elevation Pattern at 216 MHz


Enlarge Microsoft Word Document 13
enlarge 30KB, 791x1024
DOC13
HiVHF 9-El FD-Yagi - Stellar Labs 302475
4nec2 File includes Summary of Dimensions


Enlarge Microsoft Word Document 14
enlarge 26KB, 791x1024
DOC14
HiVHF 9-El FD-Yagi - Stellar Labs 302475
EVAL Summary of Performance


Enlarge HTML Document 15
enlarge 29KB, 791x1024
HTML15
HiVHF 9-El FD-Yagi - Stellar Labs 302475
EVAL *.html Performance Summary File


Enlarge photo 16
enlarge 59KB, 1024x1015
16
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 Directors
3D View


Enlarge photo 17
enlarge 170KB, 1152x629
17
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 Directors
Top View
[1 large square = 12.5 inches]


Enlarge photo 18
enlarge 115KB, 1152x428
18
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 Directors
Side View
[1 large square = 12.5 inches]


Enlarge photo 19
enlarge 181KB, 1024x647
19
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 More Directors
HiVHF Raw Gain = 8.6 to 12.0 dBi
HiVHF F/B Ratio = 14.1 dB


Enlarge photo 20
enlarge 200KB, 1024x647
20
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 More Directors
HiVHF SWR (300-ohms) Under 2.2


Enlarge photo 21
enlarge 232KB, 1024x647
21
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 More Directors
HiVHF Impedance


Enlarge photo 22
enlarge 316KB, 1024x1024
22
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 More Directors
Azimuthal Pattern at 174 MHz


Enlarge photo 23
enlarge 318KB, 1024x1024
23
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 More Directors
Azimuthal Pattern at 198 MHz


Enlarge photo 24
enlarge 317KB, 1024x1024
24
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 More Directors
Azimuthal Pattern at 216 MHz


Enlarge photo 25
enlarge 316KB, 1024x1024
25
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 More Directors
Elevation Pattern at 174 MHz


Enlarge photo 26
enlarge 316KB, 1024x1024
26
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 More Directors
Elevation Pattern at 198 MHz


Enlarge photo 27
enlarge 323KB, 1024x1024
27
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 More Directors
Elevation Pattern at 216 MHz


Enlarge Microsoft Word Document 28
enlarge 30KB, 791x1024
DOC28
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 More Directors
4nec2 File includes Summary of Dimensions


Enlarge Microsoft Word Document 29
enlarge 26KB, 791x1024
DOC29
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 More Directors
EVAL Summary of Performance


Enlarge HTML Document 30
enlarge 29KB, 791x1024
HTML30
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 More Directors
EVAL *.html Performance Summary File


Enlarge photo 31
enlarge 181KB, 1152x688
31
HiVHF 9-El FD-Yagi - Stellar Labs 302475
Front View
[1 large square = 5 inches]


Enlarge photo 32
enlarge 249KB, 1024x696
32
HiVHF 9-El FD-Yagi - Stellar Labs 302475
Compare Versions: Raw Gain & SWR


Enlarge photo 33
enlarge 269KB, 1024x696
33
HiVHF 9-El FD-Yagi - Stellar Labs 302475
Compare Versions: Raw Gain & F/R Ratio


Enlarge photo 34
enlarge 123KB, 1152x471
34
HiVHF 9-El FD-Yagi - Stellar Labs 302475
If Repurpose 2 RR's for 2 More Directors
Front View
[1 large square = 5 inches]


 
 Select All.  
  Sign the Guestbook. There are no entries.