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Arts and Crafts
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MCSQG
1. MCSQG   (10/1/14)
January BOM.
Theme:  calendar quilt
Techniques:  Applique, padded appliqué, hand or machine embroidery
101 Visits
16 Images
Linked Album
puppys2852
HIVHF+UHF VEE Folded Dipole
2. HIVHF+UHF VEE Folded Dipole  (25 Sept 2014)
Hi-VHF+UHF "VEE" Folded Dipole analyzed using 4nec2.
26 Visits
27 Images
Linked Album
holl_ands
VHF Simple-VEE-Rabbit-Ears
3. VHF Simple-VEE-Rabbit-Ears  (14 Feb 2011)
VHF Simple-VEE-Rabbit-Ears (no matching network) analyzed using 4nec2.

Hi-VHF Band Optimum Whisker Length = 14.75 for Quarter-Inch-Copper-Tubing (QICT) with Feedpoint Gap = 0.75-in.

For 45-degree Angle, Horizontal Polarization Gain was equal to Vertical Polarization Gain across the Hi-VHF Band.

Note: Even a 0.5-inch error in adjusting lengths of Rabbit Ears severely degraded SWR, although only minor impact on Raw Gain.

EDIT (10Sep2011): Added a "What-IF" exercise to illustrate the Raw Gain and SWR (if 300-ohms) from Ch2-13.
Note that SWR in Hi-VHF Band is four time higher than for 75-ohms, and becomes even more excessive on lower freqs,
as the Impedance becomes nearly all Capacitance (negative Reactance).

EDIT (16Jan2012): Added Circular Polarization Azimuthal Plots.  Note that Right Circular = Left Circular at 90-deg & 270-deg Azimuths, so there is very little suppression of Cross-Polarized (e.g. reflected Multipath) signals.

ERRATA (5Sep2014): Uploaded revised 4nec2 File with sin and cos functions reversed to match Angle Definition in Comment description.  Since all charts were for 45-degree Angle, they are NOT affected.
687 Visits
24 Images
Linked Album
holl_ands
UHF Vert 8-Bay Dipole + 43 Pair RR - OPT
4. UHF Vert 8-Bay Dipole + 43 Pair RR - OPT  (1 Sep 2014)
UHF Vertical 8-Bay FAT Dipole with 43 Pairs of Reflector Rods analyzed using 4nec2 after
determining Dimensions using nikiml's Optimization Scripts.
60 Visits
15 Images
Linked Album
holl_ands
UHF 3-Bay FAT Dipoles + 12 Pair RR - OPT
5. UHF 3-Bay FAT Dipoles + 12 Pair RR - OPT  (1 Sep 2014)
UHF 3-Bay FAT Dipoles with 12 Pair of Reflector Rods (narrow Gap in the middle) analyzed using 4nec2 after determining Dimensions using nikiml's Python Optimization Scripts.
47 Visits
21 Images
Linked Album
holl_ands
UHF Cir-Pol 5-Blade Fan
6. UHF Cir-Pol 5-Blade Fan  (29 Aug 2014)
UHF Circularly Polarized 5-Blade Fan analyzed using 4nec2.
68 Visits
48 Images
Linked Album
holl_ands
UHF 3-Bay Fat Dipole + 16 RR - OPT
7. UHF 3-Bay Fat Dipole + 16 RR - OPT  (21 Aug 2014)
UHF 3-Bay Fat Dipole + 16 Reflector Rods analyzed using 4nec2 after determining dimensions
using nikiml's Python Optimization Scripts.  Reflector Rod-to-Rod Separation was presumed
to be 2-in for an existing set of 4 ea Reflector Sub-Assemblies with 4RR each.
77 Visits
24 Images
Linked Album
holl_ands
A-C U8000 8-Bay - 9 Full-Width Refl Rods
8. A-C U8000 8-Bay - 9 Full-Width Refl Rods  (18 May 2013)
Antennacraft U-8000 8-Bay Bowtie, modified for 9 FULL-WIDTH Reflector Rods analyzed using 4nec2
(eliminated 1/4-in Gap between each Pair of Reflector Rods).

Modification reduced F/B & F/R Ratios.

Dimensions from a 4nec2 file posted by 300ohm in April 2011.
644 Visits
20 Images
Linked Album
holl_ands
Ch30 18El FD Yagi + 14RR Corner
9. Ch30 18El FD Yagi + 14RR Corner  (9 Aug 2014)
Ch30 18-Element Folded-Dipole Yagi with 14-Reflector Rod Corner Reflector analyzed using 4nec2,
after determining Dimensions using nikiml's Python Optimization Scripts.
87 Visits
13 Images
Linked Album
holl_ands
Horiz-Stack FF4+DAR Angled Against Wall
10. Horiz-Stack FF4+DAR Angled Against Wall  (9 Aug 2014)
Horizontally Stack of Free-Form 4-Bay Bowties (2xFF4) with Double Angled Reflectors (DAR) analyzed by 4nec2 when Angled Against a Metal Wall.
104 Visits
36 Images
Linked Album
holl_ands
UHF Vertical 8-Bay Dipoles + 43RR
11. UHF Vertical 8-Bay Dipoles + 43RR  (7 Aug 2014)
UHF Vertical 8-Bay Dipole Array with 43 Reflector Rods analyzed using 4nec2 after Dimensions determined using nikiml's Python Optimization Scripts.
108 Visits
15 Images
Linked Album
holl_ands
HiVHF+UHF 8-El VEE LPDA
12. HiVHF+UHF 8-El VEE LPDA  (30Jul2014)
Hi-VHF+UHF 8-El "VEE" LPDA (with Shorting Stub) analyzed using 4nec2 after Dimensions
determined using nikiml's Python Optimization Scripts.

Hi-VHF Raw Gain = 7.5 to 7.1 dBi
UHF SWR Raw Gain = 9.6 to 5.4 to 11.1 to 10.3 dBi.

Hi-VHF SWR (75-ohms) Under 2.4
UHF SWR (75-ohms) Under 4.4
and Under 2.7 above 630 MHz.
86 Visits
18 Images
Linked Album
holl_ands
Hi-VHF+UHF "VEE" Stick Dipole
13. Hi-VHF+UHF "VEE" Stick Dipole  (25 Jul 2014)
Hi-VHF+UHF "VEE" Stick Dipole (No Reflector) analyzed using 4nec2 after using nikiml's Python Optimization Scripts
to determine the "best" Element Length and Forward Swept Angle to "best" cover BOTH Hi-VHF and UHF Bands.
89 Visits
18 Images
Linked Album
holl_ands
UHF Small Rhombic Stack
14. UHF Small Rhombic Stack  (6 Feb 2011)
UHF Small Rhombic Stack analyzed using 4nec2.  Elements are AWG14: 20-in and 20.25-in long. [AWG10 & AWG12 should be similar.]
1326 Visits
17 Images
Linked Album
holl_ands
Hi-VHF Bowties - No Reflector
15. Hi-VHF Bowties - No Reflector  (2 Apr 2010)
Hi-VHF Four-Whisker, Six-Whisker, Enclosed and Indented Bowties analyzed using 4nec2.
Performance on Ch2-6 + FMBand was also analyzed.  They continue to operate as bi-directional Dipoles with low Gain and much higher SWR on the lower channels.

Six-Whisker Bowtie had better Raw Gain than Four-Whisker and much better SWR than either Four-Whisker, Enclosed or Indented Bowties.
Tine Separation is between upper and lower times.

Raw Gain and Azimuthal Gain Patterns were significantly worse for Enclosed and Indented Bowties.
1383 Visits
61 Images
Linked Album
holl_ands
 
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