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16 - 30 of 622 Total. Shared
16. HiVHF+UHF 2-Bay WallTenna Enhancements  (2 Feb 2015)
Hi-VHF and UHF 2-Bay Bowtie (7.2x8.0-in) with No Reflector analyzed using 4nec2.
Dimensions came from Actual Measurements by on the WallTenna.

Three versions were analyzed: 1) As Built, 2) Add Whisker Extensions to improve UHF performance
and 3) Add Co-Planar Rectangular Loop Resonator to improve Hi-VHF Performance.

1) WallTenna As Built:



2) Add Whisker Extensions to improve UHF performance:



3) Add Co-Planar Rectangular Loop Resonator to improve Hi-VHF Performance.
0 Visits
0 Images
Linked Album
holl_ands
UHF M4 (9.5x9.0) 4-Bay+FLAT Grid at 16"
17. UHF M4 (9.5x9.0) 4-Bay+FLAT Grid at 16"  (27 Oct 2013)
UHF M4 (9.5"x9.0") with Flat Screen Grid Reflector analyzed using 4nec2.
Dimensions for Bowties are for mclapp's M4 using AWG8 per his website drawings.
There was no attempt was made here (yet) to jointly optimize Bowtie & Reflector dimensions.

Better for HiVHF: 40-in x 40-in Screen Grid (1"x2") Reflector located 16-in behind 4-Bay Bowties,
but higher SWR on lowest UHF Channels and Gain on higher UHF channels moves to +/- 25-deg,
resulting in reduced Forward Gain.
[An improved design should be investigated, reducing these UHF degradations.]

UHF Raw Gain = 13.7 to 14.5 to 9.8 dBi, F/B & F/R Ratio Min = 10.9 dB and SWR (300-ohms)
up to 4.5 on Ch14 and under 2.7 on Ch17 and above.
Hi-VHF Raw Gain = 8.0 to 7.7 dBi, F/B & F/R Ratio = 13-15 dB and SWR (300-ohms) under 3.2.

ERRATA (27Oct2013): Corrected labels and narrative (charts remain the same).
Separation between Reflector and Bowties for the two alternatives is actually 16-in (vice 17-in).
When defining nec file names, I overlooked -1 inch offset in the Bowties.
1183 Visits
21 Images
Linked Album
holl_ands
HiVHF+UHF 2-Bay+Loop - NO Reflector
18. HiVHF+UHF 2-Bay+Loop - NO Reflector  (27 Jan 2015)
Hi-VHF + UHF 2-Bay Bowtie plus Hi-VHF Rectangular Loop Resonator analyzed using 4nec2.

Two versions were analyzed: a) mclapp M2 (9.5x9.0) sized 2-Bay plus Rectangular Loop and b) Re-Optimized 2-Bay plus Rectangular Loop.

a) mclapp M2 (9.5x9.0) sized 2-Bay plus Rectangular Loop, where Loop is in the same plane and always OUTSIDE the 2-Bay.

b) Re-Optimized 2-Bay plus Rectangular Loop, with 0.5-in Offset between them to avoid overlapping wire collisions.
168 Visits
39 Images
Linked Album
holl_ands
Horiz-Stack 2xFF4 + DoubleAng Refl - RFC
19. Horiz-Stack 2xFF4 + DoubleAng Refl - RFC  (3 Jun 2014)
UHF+Hi-VHF HFF8, a Horizontal Stack of 2 ea Free-Form 4-Bays (FF4) with Double Angle Reflectors
(each 48" H x 36" W using 2x2-in Grid) were analyzed using 4nec2, presuming they are driven separately.
FF4 dimensions are sameas found for the Optimized version with
a Variable Double Angle Reflector.

Here the usual Horizontal Stacking approach is used, with Equal Length Coax to a (ZERO LOSS) RF Combiner.

Initially, 4nec2 Parameter Sweep plotted Raw Gain versus Horizontal Stacking Distance.
Since SWR plots were always excellent across the UHF Band, they are not shown here.

Performance was slightly "Better" at THREE notable Stacking Distances:
34.821-inches (NO GAP, Continuous Reflector), 35-inches (Metal-to-Metal about 1/4-inch)
and 51-inches, which are analyzed below.
There were notable Stacking Distances further out, but none were particularly "Better".

Although the differences are only a few tenths of a dB, Stack Distance = 51-inches was just
a bit "Better", esp. Hi-VHF, than at 35-inches.  The wider Separation may also be slightly
"Better" at combating Multipath Fading due to the reduction in Statistical Correlation
between the two Antenna signals.  The "NO GAP between Reflector" alternative was slightly worse.

===========================================
a) Horizontal Stacking Distance (4-Bay Center-to-Center) = 34.821 inches (NO GAP between Reflectors).

UHF Raw Gain = 17.2 to 19.7 dBi, F/B & F/R Ratio Minimum = 16.4 dB & SWR (300-ohms) under 2.1.
Hi-VHF Raw Gain = 10.4 to 9.9 to 10.3 dBi, F/R & F/B Ratio Min = 16.4 dB, although SWR (300-ohms)
under 20 dB is EXCESSIVE, which may or may NOT be an issue in any particular situation.

===========================================
b) Horizontal Stacking Distance (4-Bay Center-to-Center) = 35-inches (0.18-in GAP between Reflectors).

UHF Raw Gain = 17.3 to 20.1 dBi, F/B & F/R Ratio Minimum = 15.8 dB & SWR (300-ohms) under 2.1.
Hi-VHF Raw Gain = 10.5 to 11.7 to 11.9 dBi, F/R Ratio = 11.6 to 14.9 dB, although SWR (300-ohms)
= 24 to 15 dB is EXCESSIVE, which may or may NOT be an issue in any particular situation.

===========================================
c) Horizontal Stacking Distance (4-Bay Center-to-Center) = 51-inches (16.18-in GAP between Reflectors).

UHF Raw Gain = 17.6 to 20.3 dBi, F/B & F/R Ratio Minimum = 14.2 dB and SWR (300-ohms) under 2.1.
Hi-VHF Raw Gain = 13.5 to 11.4 dBi, F/R Ratio = 9 to 19 dB, although SWR (300-ohms) = 29 to 22 dB
is EXCESSIVE, which may or may NOT be an issue in any particular situation.
307 Visits
69 Images
Linked Album
holl_ands
Hi-VHF+UHF Tapered Loop - C2V
20. Hi-VHF+UHF Tapered Loop - C2V  (18Jan2015)
Hi-VHF and UHF Tapered Loop with Screen Grid Reflector PLUS Hi-VHF Stick Dipole (aka Clearstream C2-V Replica)
analyzed using 4nec2.  All dimensions are approximations, C2-V may be somewhat different.

Three variations were analyzed: C2-V with Hi-VHF Dipole, UHF-ONLY C2 with Reflector and C2 without Reflector.

a) Tapered Loop with Screen Grid Reflector PLUS Hi-VHF Dipole:

b) Tapered Loop with Screen Grid Reflector:

c) Tapered Loop without Reflector:
52 Visits
52 Images
Linked Album
holl_ands
my paintings
21. my paintings  (ongoing)
my watercolor paintings
78 Visits
34 Images
Linked Album
lefialynn
vstackuhfquadtraploopxxrr
22. vstackuhfquadtraploopxxrr  (30 Dec 2014)
Vertical Stack of UHF Quad-Trapezoid-Loops with xx Reflector Rods analyzed using 4nec2 after determining Optimum Dimensions using nikiml's Python Optimization Scripts.

a) UHF Quad-Trap-Loop with 15 Reflector Rods:
96 Visits
24 Images
Linked Album
holl_ands
Hi-VHF Hourglass Loop
23. Hi-VHF Hourglass Loop  (30 Nov 2012)
Hi-VHF Hourglass Loop analyzed using 4nec2 after finding "best" dimensions using nikiml's Optimization
Scripts.  Based on UHF Hourglass Loop posted by oneolddude in www.digitalhome.ca forum:
1/4-in O.D. Elements and Reflector Rods.

NO Reflector Rods (Optimized H=41.75-in, W=34.5-in & Feedpoint Gap=2.5-in):
Ch7-13 Raw Gain = 5.3-6.1 with Excellent SWR under 1.6 (using Quarter-inch Copper Tubing).
Provides about 4 dBi Raw Gain on Ch2-6 and FM Band, but SWR is excessive.
Also provides some Raw Gain with acceptable SWR in UHF Band, but only over mid-band frequencies.

Charts assume Quarter-Inch-Copper, e.g. Tubing or RG-59 braid shield (no need to strip insulation).
Much smaller size AWG12 wire has NO effect on Gain and only increases SWR to 2.0,
so feel free to use even smaller wire sizes.

Add 15 Reflector Rods (Optimized Width, Rod-Rod Separation & Separation from Hourglass):
Ch7-13 Raw Gain = 9.7-10.05 dBi with SWR under 3.1 (using Quarter-inch Copper Tubing).  
Reflector Total Height = 68-in x Width = 56.5-in.
Excellent Front/Rear (hemisphere) Ratio = 32-34 dB with Front/Back (toward 270-deg) = 20 dB.
Provides some Raw Gain on Ch2-6 and FM Band, but directed to the REAR and SWR is excessive.
Not suitable for UHF Band: poor SWR & Gain toward Diagonals.

With 15-RR, provides Gain nearly as much as Winegard YA-1713, except sidelobe nulls moved
to sides and consistently EXCELLENT F/B and F/R Ratios.

EDIT (4Jun2013): Added Hourglass with 11 Reflector Rods and with 7 Reflector Rods to illustrate
how much reduction to expect in Gain and F/R Ratio.  Also note that Reflector Height and Width are
significantly smaller.

EDIT (6Jun2013): Added Comparison Chart showing improvement in Raw Gain & F/R Ratio with more RRs.

EDIT (14Dec2014): Added 5RR and 3RR versions.
2760 Visits
70 Images
Linked Album
holl_ands
UHF Vertical 6-Bay Bowtie - NO Refl
24. UHF Vertical 6-Bay Bowtie - NO Refl  (11 Dec 2014)
UHF Vertical Vertical 6-Bay Bowtie (FF6) with NO Reflector analyzed using 4nec2 after finding best Dimensions
using nikiml's Python Optimization Scripts.
255 Visits
18 Images
Linked Album
holl_ands
Matt
25. Matt  (12/07/2014)
166 Visits
2 Images
Linked Album
tuttles
26. Wheel Chairs 
0 Visits
0 Images
Linked Album
bloodandwhiskeydesign
Clocks
27. Clocks  
179 Visits
4 Images
Linked Album
bloodandwhiskeydesign
Tools
28. Tools 
192 Visits
14 Images
Linked Album
bloodandwhiskeydesign
mcsqg-march
29. mcsqg-march  (12/1/14)
Will be making a St. Patrick's day block for March.
This block has appliqué technique.
The alternate block will be from quilterscache.com/four winds
This is a pieced block.
138 Visits
11 Images
Linked Album
puppys2852
uhf4bayhourglassloopsnorefl
30. uhf4bayhourglassloopsnorefl  (28 Nov 2014)
uhf3bayhourglassloopsnorefl
UHF 3-Bay Hourglass-Loop (NO Reflector) analyzed using 4nec2 after determining best Dimensions using nikiml's Python Optimization Scripts.
232 Visits
60 Images
Linked Album
holl_ands
 
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