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UHF Slotted Cylinder - Horizontal Polar.
1. UHF Slotted Cylinder - Horizontal Polar.  (29 Aug 2015)
UHF Slotted Cylinder Slot Antenna with Horizontal Polarization analyzed using 4nec2.  From x-731 (now Post # 726) design posted by Bokabob on www.digitalhome.ca Antenna Design Forum.
25 Visits
17 Images
Linked Album
holl_ands
HiVHF+UHF Scatter Forger Slot Antenna
2. HiVHF+UHF Scatter Forger Slot Antenna  (29 Aug 2015)
Hi-VHF + UHF "Scatter Forger" Slot Antenna Analyzed using 4nec2.
20 Visits
18 Images
Linked Album
holl_ands
Ch2-69 + FM Crossed Loops - UVOX-2
3. Ch2-69 + FM Crossed Loops - UVOX-2  (23 Aug 2015)
Ch2-69 + FM Band Circular Crossed Loops were analyzed using 4nec2.
For the purpose of this analysis, Dimensions for the OMNI UVOX-2 were
assumed, per info on their website: http://www.omnitenna.com

Not knowing the particulars of the internal design, TWO versions are analyzed here:

======================================
a) Feedpoint Gaps at bottoms of both Loops are Directly Interconnected using short wires.
Azimuthal Pattern is BI-DIRECTIONAL across ALL Frequency Bands for BOTH
Horizontal and RHCP (Right-hand Circular Polarization).

======================================
b) A Transmission Line (located within the support structure) Interconnects both Loops.
TL Length chosen for Max Gain and Minimum Null Depth for Horizontal or RHCP.
Azimuthal Pattern is BI-DIRECTIONAL across ALL Frequency Bands for BOTH
Horizontal and RHCP (Right-hand Circular Polarization), except at
highest Frequencies degenerates to a FOUR-LOBE Pattern.
Note Max Gain Axis Rotation across Hi-VHF Band, so Max Gain in Lo-VHF Band
aligns with NULLs in other Bands.
33 Visits
78 Images
Linked Album
holl_ands
Ch2-69 Crossed Loops 90-deg Phase Shift
4. Ch2-69 Crossed Loops 90-deg Phase Shift  (25 Aug 2015)
Ch2-69 Circular Crossed Loops driven by FULL BAND 90-deg Phase Shifter
analyzed using 4nec2. (e.g. Low Loss Ch2-69 Quadrature Hybrid...if only
such a device existed!!!!!)
For the purpose of this analysis, Dimensions for the OMNI UVOX-2 were
assumed, per info on their website: http://www.omnitenna.com

FYI: Minicircuits PROTOTYPE SXPQ-ED14355-1 covers Ch2-18, which is 200 MHz short of what is needed:
http://www.minicircuits.com/pdfs/SXPQ-ED14355-1_SPEC.pdf
And Minicircuits QCN-8+ device covers entire UHF Band:
http://www.minicircuits.com/pdfs/QCN-8+.pdf

An IDEALIZED, PERFECT 2-Port 90-Degree Phase Shift Network feeds both Loops.
Although Low Loss "Quadrature Hybrids" are only available ABOVE UHF TV Freqs.

Azimuthal Pattern is TRUE OMNI from Ch2 thru Ch13, including FM Band.

In UHF Band, some Gain Loss is seen in the CLOVER-LEAF NULLs, which becomes
deeper on the mid to upper Frequencies.
22 Visits
42 Images
Linked Album
holl_ands
Hi-VHF A-C Y-10-7-13 Dual-Driven Yagi
5. Hi-VHF A-C Y-10-7-13 Dual-Driven Yagi  (25Jan2011)
Antennacraft Y-10-7-13, 10-Element, 177.4-in boom, Hi-VHF Dual-Driven Yagi analyzed using 4nec2.

Original 4nec2 file and measurements by tripelo on an antenna provided by re_nelson.  Boom Length=117-in.
Note that the two Driven Elements are the SAME size with an IN-PHASE (not quite) QUARTER-WAVELENGTH feedline,
rather than different length elements with HALF-WAVELENGTH CROSSOVER feedline used in a Log-Yagi.

holl_ands 4nec2 mods: Autosegment(21), variable Rsrc to adjust AGT=1.0, decimal roundoffs and various RP/FR statement choices.

The first set of curves assume a Half-Element Boom Correction of 0.125-inch (tripelo's guess).
The second set of curves assumes ZERO Boom Correction, which is closer to the Top-Of-Boom derating per
discussion found in YA-1713 album.  Note 4nec2 predicted improvement in Ch13 Raw Gain & SWR....but predicted
Ch7 Raw Gain roll-off is about the same.

Ch7-12 Raw Gain = 7.5 to 12.8 dBi, but Ch13 Rolloff May NOT be Real.
1947 Visits
22 Images
Linked Album
holl_ands
A-C Y-10-7-13 plus 2 RR's & 3 Dirs
6. A-C Y-10-7-13 plus 2 RR's & 3 Dirs  (20 Aug 2015)
Antennacraft Y-10-7-13 10-Element Dual-Driven Yagi PLUS two Additional Reflector Rods
and three Director Rods analyzed using 4nec2.

Additional Elements come from Front Boom and Rear Reflector Pair from re-purposed
MCM Stellar Labs 30-2475 8-El Folded Dipole Yagi, analyzed here:
http://imageevent.com/holl_ands/yagis/hivhf8elfdyagistellarlabs

Ch7-12 Raw Gain = 9.7 to 14.0 dBi, but Drop Off on Ch13 Might NOT be Real.
Ch7-12 SWR (300-ohms) under 2.1, but Rise on Ch13 Might NOT be Real.
36 Visits
15 Images
Linked Album
holl_ands
HiVHF 8-El FD-Yagi - Stellar Labs 302475
7. HiVHF 8-El FD-Yagi - Stellar Labs 302475  (20 Aug 2015)
Hi-VHF 8-Element Folded Dipole Yagi, MCM Stellar Labs 30-2475, analyzed using 4nec2.
Dimensions provided by user .

Hi-VHF Raw Gain = 8.6 to 10.5 dBi, F/B & F/R Ratio = 9.9 to 20.5 to 14.6 dB
[Poor on Lower Channels] and SWR (300-ohms) is Under 3.0.

Note that Triple Reflector Rods at the Rear did NOT provide adequate F/B & F/R Ratio performance.

Compare to OPTIMIZED 8-El FD-Yagi with only ONE Reflector Rod, with two additional Directors instead:
52 Visits
12 Images
Linked Album
holl_ands
UHF 7-EL-Pair LPDA - Silver Sensor
8. UHF 7-EL-Pair LPDA - Silver Sensor  (11 Aug 2015)
UHF 7-Element-Pair LPDA (Log Periodic Dipole Array) with Swept Back Elements,
aka SILVER SENSOR, analyzed using 4nec2.
Note that Characteristic Impedance is 75-ohms.

UHF Raw Gain = 6.5 to 7.4 to 7.0 dBi, F/B & F/R Ratio Min. = 16.8 dB and
SWR (300-ohms) Under 2.6.

Hi-VHF Raw Gain = 1.0 to 1.7 to 1.9 dBi, F/B & F/R Ratios = 0.1 to 0.4 dB and
SWR (75-ohms) = 2840 to 400 is Excessive.
36 Visits
21 Images
Linked Album
holl_ands
UHF 7-El-Pair LPDA - Terk HDTVi
9. UHF 7-El-Pair LPDA - Terk HDTVi  (11 Aug 2015)
UHF 7-Element-Pair LPDA (Log Periodic Dipole Array) with Swept Forward Elements,
aka Terk HDTVi and HDTVa, analyzed using 4nec2.  Note that Characteristic Impedance is 75-ohms.

UHF Raw Gain = 6.0 to 6.9 dBi, F/B & F/R Ratios = 8.4 to 17.0 dB and SWR (300-ohms) Under 3.9 is Higher than Desired.

Hi-VHF Raw Gain = 3.0 to 2.7 dBi, F/B & F/R Ratios = 0.3 to 0.6 dB and SWR (300-ohms) Under 110 is Excessive.
41 Visits
21 Images
Linked Album
holl_ands
UHF + Hi-VHF V-Hawk by Ronbo
10. UHF + Hi-VHF V-Hawk by Ronbo  (4 Aug 2015)
Hi-VHF + UHF V-Hawk Antenna analyzed using 4nec2.
Dimensions as per 4nec2 Files posted by user Ronbo.

Three versions were analyzed, with  30, 45 and 60-deg Forward Swept Angles:

====================================
a) UHF + Hi-VHF V-Hawk - 30-deg Angle:

UHF Raw Gain = 10.8 to 14.3 to 10.7 dBi and SWR (300-ohms) under 1.8,
with Primary Lobe Forward and Secondary Lobes 110 to 120-deg away.

Hi-VHF Raw Gain = 5.2 to 6.2 dBi, F/B & F/R = 0.3 to 0.4 dB and
SWR (300-ohms) under 2.3 with Bi-Directional, Quasi-Omni Coverage.

====================================
b) UHF + Hi-VHF V-Hawk - 45-deg Angle:

UHF Raw Gain = 9.6 to 14.3 to 12.2 dBi and SWR (300-ohms) Under 1.8,
with Primary Lobe Forward and Secondary Lobes about 90-deg away.

Hi-VHF Raw Gain = 4.6 to 5.3 dBi and F/B & F/R = 0.5 to 0.7 dB and
SWR (300-ohms) under 2.3 with Bi-Directional, Quasi-Omni Coverage.

====================================
c) UHF + Hi-VHF V-Hawk - 60-deg Angle:

UHF Raw Gain = 7.6 to 12.3 to 10.3 dBi and SWR (300-ohms) under 2.3 with
Very Wide Beamwidth Forward and minimal Gain to Rear.
176 Visits
64 Images
Linked Album
holl_ands
Vert-Stack FF4 SingleAngleRefl Sidelobes
11. Vert-Stack FF4 SingleAngleRefl Sidelobes  (31Jul2015)
Vertical Stack FF4 (Free Form 4-Bay Bowtie) with Single Angle Reflector (providing Deep Sidelobe Nulls) analyzed using 4nec2.  HVH (Holl_ands Vertical Harness) dimensions were determined using nikiml's Python Optimization Scripts.  Each FF4 was assumed to be identical to the OPTIMUM non-stacked version found here: http://imageevent.com/holl_ands/multibay/4bayrefl/uhffreeform4baysnglanglrefldeepsidelobes
72 Visits
21 Images
Linked Album
holl_ands
Skickley desk
12. Skickley desk 
88 Visits
6 Images
Linked Album
kentuckyindianalocations
Stilgenbauer Art
13. Stilgenbauer Art  
285 Visits
18 Images
Linked Album
coastcnc
Gallows Gallup
14. Gallows Gallup  (July 12, 2015)
highways
coaxial
petra
china
581 Visits
76 Images
Linked Album
ravenbarter
15. After Paradise 
122 Visits
0 Images
Linked Album
bloodandwhiskeydesign
 
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