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UHF FF3 3-Bay Bowtie - NO Reflector
16. UHF FF3 3-Bay Bowtie - NO Reflector  (21 Oct 2015)
UHF Free-Form 3-Bay (FF3) analyzed using 4nec2 after determining Dimensions using
nikiml's Python Optimization scripts.

Three alternative interconnection Topographies were determined to be of interest for further
investigation (starting with the BEST).  Nearly ALL Bowtie Parameters were allowed to be
INDEPENDENTLY varied in determining the fol. three versions of the FF3 (Free-Form 3-Bay Bowtie):

Note that Gain Charts are for TOTAL (Horiz. + Vert.) Gain.  Azimuthal Charts show that
there is lower, but significant Vertical Gain to the SIDES of the Antenna.

a) Remove Top Bowtie from FF4 (so Offset Feedpoint) and Re-Optimize:

UHF Raw Gain = 8.6 to 11.4 dBi and SWR (300-ohms) Under 2.7 is Good.
Hi-VHF Raw Gain = 2.4 to 3.0 dBi and SWR (300-ohms) = 3.9 to 6.3 is Higher than Desired.

b) Move Feedpoint to Inner Bowtie with Crossover Feedlines to each Outer Bowtie, which
are presumably needed to ensure all three signals are In-Phase at the Feedpoint:

UHF Raw Gain = 8.1 to 10.1 dBi and SWR (300-ohms) Under 2.6 is Good.
Hi-VHF Raw Gain = 2.6 to 2.9 dBi and SWR (300-ohms) = 9.4 to 2.1 is Excessive on Ch7-11.

c) Offset Feedpoint (like a), but with Straight (NO Crossover) Feedlines to each Outer Bowtie:

UHF Raw Gain = 7.1 to 9.4 to 9.1 to 10.7 dBi and SWR (300-ohms) Under 3.1 is a Bit Higher then Desired.
Hi-VHF Raw Gain = 2.1 to 2.6 dBi and SWR (300-ohms) = 7.8 to 6.4
is Excessive.
1168 Visits
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UHF M3 3-Bay Bowtie - NO Reflector
17. UHF M3 3-Bay Bowtie - NO Reflector  (20 Oct 2013)
UHF 3-Bay Bowtie [aka M3 (9.5x9.0)] with NO Reflector analyzed using 4nec2.
Height=21-inches, Width=20-inches.

One Bowtie on the M4 (9.5x9.0) 4-Bay Bowtie Antenna was removed to determine the performance of a SHORTER 3-Bay version.
The TOP rather than the BOTTOM Bowtie was removed since it results in a slightly UPWARD tilt (5-10 deg) in the Elevation Pattern in UHF Band.

Raw Gain in the Hi-VHF Band on all but the lowest channels was severely affected as the Gain Pattern shifted to the OVERHEAD direction.
3493 Visits
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UHF Multi-Bay Comparison Charts
18. UHF Multi-Bay Comparison Charts  (17 Aug 2009)
Old (Ch14-69) UHF Band is from 470-806 MHz.  New UHF Band is 470-698 MHz.

NOTE: Due to complexity limits in 4nec2 modeling program, most FF4 Reflector models were forced to use
sparse Grid Size (e.g. 4"Hx4"W).  If normal 1"Hx2"W Grid Size is used, F/B and F/R Ratios are significantly improved.

A. Vertically Stacked Comparisons of 2xFF4, 2xM4, 2xCM4221, 2x91XG vs FF6 and two Parabolics:
i) CM4251 and ii) 8-El LPDA with 1-m Refl. & 4ea 1x1-m Refl.

B. FF4, 91XG and Wider Bowtie Modified 91XT Performance Curves for Comparison purposes (not yet
integrated into a single Chart).

C. Multi-Bay Comparisons, presuming NO REFLECTORS and Flat Bowties:

C1. EV's SuperQuad (9.75x9.5) 4-Bay optimized for more Gain on low-mid UHF channels.
C2. mclapp's M4 (9.5x9.0) Super-4-Bay is not only optimized for New UHF Band, but also has low SWR
throughout Hi-VHF Ch7-13.
C3. mclapp's (9.5x9.0x8.5) per his posted 4nec2 file has improved Gain on Ch52-69, but increasing SWR
on Hi-VHF Ch7-9 degrades Net Gain.
C4. Channel Master CM4221 (8.5x8.9), per Actual measurements, is a good performer
on Old and New UHF Bands, but Hi-VHF SWR is somewhat degraded on Ch7-9.
C5. Channel Master CM4221 (7.8x8.0), per Ken Nist's measurements in CM4221a.ez EZNEC file is also a good performer
on Old and New UHF Bands, but SWR and Net Gain are severely degraded on lowest UHF and all Hi-VHF channels.
C6. UTube 4-Bay (from Babblin5 or MakeTV) is a very low performer on both UHF and Hi-VHF Bands, due to insufficient
Bowtie-to-Bowtie separation (5.75-in vs 9.0-in).
C7. Compare Bowties: FF6 (Free-Form 6-Bay) vs FF4 (Free-Form 4-Bay), M4 (9.5x9),
CM4221 (8.5x8.9), CM4221HD (7.9x9.8) and DB-4 (TOO SMALL 6.2x7.9).

D. Multi-Bay Comparisons, presuming Screen REFLECTORS and FLAT Bowties
(Angle along centerline for SuperQuad, Outer 10-inches Angled Forward for M4 and Flat for CM4221) and Flat Bowties:

D1. EV's SuperQuad (9.75x9.5) 4-Bay optimized for more Gain on higher UHF channels.
D2. mclapp's M4 (9.5x9.0) Super-4-Bay is not only optimized for New UHF Band, but also 7.0-3.0 dBi Net Gain
across the Hi-VHF Band, with lowest SWR on Ch7.
D3. Channel Master CM4221 (8.5x8.9), per Actual measurements is a good performer on Old and especially New UHF Bands,
but Hi-VHF SWR and Net Gain are seriously degraded, esp on Ch7-9.  Hi-VHF Gain is 3.5 to 6.5 dB HIGHER
towards the REAR than the FRONT.
D4. Channel Master CM4221 (7.8x8.0), per Ken Nist's measurements in CM4221a.ez EZNEC file is a good performer
on Old and New UHF Bands, but SWR and Net Gain are severely degraded on lowest UHF and all Hi-VHF channels.

E. Multi-Bay Comparisons, presuming Screen REFLECTORS and SWEPT Bowties
(Angle along centerline for SuperQuad, Outer 10-inches Angled Forward for M4 and Flat for CM4221) and Flat Bowties:

E1. EV's SuperQuad (9.75x9.5) 4-Bay optimized for more Gain on higher UHF channels.
E2. mclapp's M4 (9.5x9.0) Super-4-Bay is also optimized for New UHF Band with more gain on lower UHF channels.
Both antennas suffered from excessive SWR in the Hi-VHF Band.

F. Combiner Mod for Old CM4228 compared to original crossover between the two 4-Bay stacks.  Also compared to various
4-Bay antennas.  Above Ch51: Significant improvement. Lowest UHF channels: 3 dB improvement in Raw Gain but only
minor improvement in Net Gain due to poor SWR.

G. New CM4228HD (As Shipped) was much better than old CM4228 on the (problematic) lowest channels,
but had 1-2 dB lower Gain above Ch30.
New CM4228HD was actually somewhat worst than mclapp M4 Super-4-Bay, esp on lowest channels.

H. Combiner Mod for New CM4228HD compared to "As Shipped" to illustrate how much is lost in the horizontal interconnect.
If a low loss RF Combiner Module is used (not an easy task), more than 2 dB of improvement MIGHT be possible...
CM4228HD with Hollands Horizontal Harness (HHH) Mod, essentially MATCHES the RF Combiner Mod UHF Band improvements.

I. Compared fol. 2-Bays+11RR: Triangles, H2 Bowties, Quad-Traps, Bi-Quads, Twin-Loops and Hourglass-Loops.

J. Compared fol. 2-Bay Bowties w/o Reflector: mclapp M2 (9.5x9.0), M2 (10.0x9.5) and the OPTIMIZED H2 (12x11),
with significantly better UHF and Hi-VHF performance.
16187 Visits
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2m Stick Vertical Dipole
19. 2m Stick Vertical Dipole  (8 Oct 2015)
2-meter Stick Vertical Dipole analyzed using 4nec2.

Raw Gain = 2.05 to 2.13 to 2.22 dBi and SWR (300-ohms) Under 1.44 at 145 MHz
and Under 2.0 from 141 to 150 MHz.

Vertically Polarized Antenna with True OMNI-Directional Response and
minimal Response to Horizontally Polarized signals.

True OMNI, RHCP (Right Hand Circular Polarization) = LHCP (Left Hand Circular
Polarization), so no suppression of Multipath Reflections.
619 Visits
18 Images
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20. 2m Lindenblad Parasitic + Vert. Dipole  (7 Oct 2015)
2-meter (145 MHz) Lindenblad Parasitic Array with Vertical Dipole Active Element analyzed using 4nec2.

Based on lindnbld.ez (EZNEC) File downloaded from http://nec-archives.pa3kj.com/EZNEC_FILES,
which was Imported into 4nec2 and then converted into a Variable SYmbol driven File to facilitate
further analysis, as shown below with Vertical Dipole added.

Vertical Dipole and Parasitic Diagonal Element Lengths were adjusted for minimum SWR (50-ohms)
and minimum LHCP on 145 MHz, assuming Diagonals at 45-deg Angles and separated 1/4-wavelength
away from the Center of the Antenna.  All Elements are AWG12 Copper Wire.

For signals with RHCP (Right Hand Circular Polarization), the Azimuthal Patter is very OMNI.
However, for signals with mostly Horizontal Polarization, there is significantly lower Gain.

When signals are reflected, they usually undergo a change from RHCP to LHCP.  This version of the
Lindenblad Omni Array provides a moderate amount of suppression of these Multipath Reflections.

Parasitic Elements significantly improve Raw Gain Max = 2.9 dBi at 145 MHz and
the Length of the Vertical Dipole has also been adjusted for SWR Min at 145 MHz,
while also adjusting Lengths of Diagonal Parasitic Elements for LHCP Min at 145 MHz.

Note that response to primarily Horizontally Polarized signals is significantly reduced.
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21. 2m Lindenblad Omni Array  (7 Oct 2015)
2-meter (145 MHz) Lindenblad Omni Array analyzed using 4nec2.  Based on lindnbld.ez (EZNEC) File
downloaded from http://nec-archives.pa3kj.com/EZNEC_FILES, which was Imported into 4nec2
and then converted into a Variable SYmbol driven File to facilitate further analysis, as shown below.
NONE of the Dimensions have been changed, including the Diagonals being at 46.91-deg (vice 45-deg) Angles.

In this version, separate SOURCEs are used on each Element.  In a REAL Antenna, a 4-Way Feedline
would be used, which would likely degrade performance relative to what is shown here.

For signals with RHCP (Right Hand Circular Polarization), the Azimuthal Patter is very OMNI.
However, for signals with mostly Horizontal Polarization, there is significantly lower Gain.

When signals are reflected, they usually under go a change from RHCP to LHCP.  The Lindenblad Omni Array
provides a moderate amount of suppression of these Multipath Reflections.
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Horiz-Stack 2xFF6 + VDAR + HHH
22. Horiz-Stack 2xFF6 + VDAR + HHH  (29 Sep 2015)
UHF Horizontally-Stacked 2xFF6's each with Variable Double Angled Reflector (VDAR, 60"Hx36"W)
(all 19 Variables Searched for Optimum) analyzed using 4nec2.

UHF Raw Gain = 17.7 to 19.5 to 18.9 to 19.6 dBi, F/B & F/R Ratio Minimum = 14.9 dB and
SWR (300-ohms) Under 2.2.  [Raw Gain = 19.0 dBi +/- 0.6 dB, except 17.7 dBi at 470 MHz.]
Hi-VHF Raw Gain = 12.2 to 12.6 to 11.1 dBi, F/B & F/R Ratio Minimum = 13.1 dB and
Hi-VHF SWR (300-ohms) = 10.7 to 26.0 to 13.5 is Excessive.
571 Visits
22 Images
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UHF Slotted Cylinder - Horizontal Polar.
23. 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.
877 Visits
17 Images
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HiVHF+UHF Scatter Forger Slot Antenna
24. HiVHF+UHF Scatter Forger Slot Antenna  (29 Aug 2015)
Hi-VHF + UHF "Scatter Forger" Slot Antenna Analyzed using 4nec2.
882 Visits
18 Images
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Ch2-69 + FM Crossed Loops - UVOX-2
25. 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.
881 Visits
78 Images
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Ch2-69 Crossed Loops 90-deg Phase Shift
26. 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.
840 Visits
42 Images
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Hi-VHF A-C Y-10-7-13 Dual-Driven Yagi
27. 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.
2601 Visits
22 Images
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A-C Y-10-7-13 plus 2 RR's & 3 Dirs
28. 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.
423 Visits
15 Images
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29. 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:
259 Visits
0 Images
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UHF 7-EL-Pair LPDA - Silver Sensor
30. 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.
264 Visits
21 Images
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