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Hi-VHF+UHF Tapered Loop - A-D C2 & C2-V
Hi-VHF and UHF Tapered Loop with Screen Grid Reflector PLUS Hi-VHF Stick Dipole analyzed
using 4nec2, approximating Dimensions for Antennas-Direct C2-V.  

DIMENSIONS Per ADTech and user freezer:
Inner Loop Diameter 6-1/4", Outer Loop Diameter 8-5/8" with 1/2" Overlap at Feedpoint.
Gen-I/II VHF Dipole = 37-7/8-in, Reflector = 20-1/8" H x 11-5/8" W x 4-1/16" "Deep".
Feedpoint DETAILS found towards the bottom of fol. webpage:
http://www.hdtvprimer.com/ANTENNAS/TemporaryPage.html

ADTech indicated that there are actually THREE DIFFERENT Generations of the C2-V, using
different VHF Impedance Matching Approaches [NOT analyzed in below results]:
"First and second generation C2Vs used a standard 300/75 ohm matching transformer to match
the dipole to the Holland UVSJ's VHF input. Because of the built-in mismatch, the length
of the dipoles was increased to bring the return loss back down in the center of the VHF band.
Third generation C2Vs that utilize the VHF-1 module utilize a custom PCB matching network
that's closer to a 1:1 ratio, allowing the dipole elements to be shortened by 3.25" inches each
while still having the best return loss at mid-band. The VHF-1 module includes the UVSJ
function internally."

======================================
Four variations were analyzed: UHF C2 with Reflector, Gen-I/II C2-V adding Hi-VHF Dipole, Gen-III/VHF Module
C2-V and C2 without Reflector.

a) C2 Tapered Loop with Screen Grid Reflector:

UHF Raw Gain = 9.6 to 10.1 dBi, F/B & F/R Minimum = 14.9 dB and SWR (300-ohms) Under 1.9.
[A-D C2 Specs: Gain = 9.7 to 10.2, F/B = 20 dB (typ), 22 dB (max at 698 MHz) and SWR (300-ohms) under 3.0.]

======================================
b) Gen-I/II C2-V Tapered Loop, Screen Grid Reflector + Hi-VHF Dipole, connected to UVSJ via 300:75-ohm Balun:

UHF Raw Gain = 9.4 to 10.1 dBi, F/B & F/R Ratio Minimum = 17.9 dB and SWR (300-ohms) Under 2.4.
Hi-VHF Raw Gain = 2.7 to 3.2 dBi, Hi-VHF F/B & F/R Ratio = 0.3 to 0.6 dB and SWR (300-ohms) Under 2.4.

Note the mid-band UHF Loss of about 0.5 dB when adding the VHF Dipole.

Note that despite the VHF Dipole being slightly SHADED by being mounted BEHIND the Reflector,
Hi-VHF Gain was 0.9 to 1.2 dB HIGHER than JUST an Optimized Hi-VHF Dipole [see Link below],
with 0.25 to 0.5 dB MORE in the Forward Direction, so the Reflector must have been acting to
squeeze out more Gain at the expense of Horizontal and Vertical Beamwidths. Also note that
the Side NULLS were limited to about -17 to -15 dBi Gain [A-D calculated -16 to -14 dBi],
rather than forming very deep Nulls more typical of a Dipole without other surrounding Metal:
https://imageevent.com/holl_ands/dipoles/hivhfuhfstickdipolenoreflector

======================================
c) Gen-III/VHF Module C2-V Tapered Loop, Screen Grid Reflector + Hi-VHF Dipole,
combined with UHF Coax via Impedance Matching Network:

T.B.D.

======================================
d) C2 Tapered Loop with Reflector REMOVED, so Bi-Directional:

UHF Raw Gain = 5.5 to 6.8 dBi and SWR (300-ohms) Under 3.2.

Note that INCREASE in Raw Gain is quite significant as the Thickness (Relem) becomes as thin as Aluminum Foil...with INCREASE
to excessive SWR=4.0 at 470 MHz.  Al. Foil Relem(STD)=0.000315-in and Relem(HD)=0.00047-in.
However, note that assumed Relem=0.0404 (14-Gauge...or perhaps thinner 16-Gauge) is best match to A-D C2 Specs, esp. SWR.
In below Charts [#52-57], Alum. Foil is on Far Left and AWG-16 on Far Right.

======================================
EDIT (2Apr2015): Uploaded revised charts based on refined dimension information from ADTech.

EDIT (4Dec2016): Added charts showing how Raw Gain INCREASES as the Thickness (Relem) is reduced.
Date(s): 18Jan2015. Album by holl_ands. 1 - 57 of 57 Total. 9789 Visits.
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Enlarge photo 1
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1
H+U Tapered Loop + Refl. Screen
A-D C2 - 3D View


Enlarge photo 2
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2
H+U Tapered Loop + Refl. Screen
A-D C2 - Front View
[1 large square = 2.5 inches]


Enlarge photo 3
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3
H+U Tapered Loop + Refl. Screen
A-D C2 - Side View
[1 large square = 1.25 inches]


Enlarge photo 4
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4
H+U Tapered Loop + Refl. Screen
A-D C2
UHF Raw Gain = 9.6 to 10.1 dBi
UHF F/B & F/R Minimum = 14.9 dB


Enlarge photo 5
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5
H+U Tapered Loop + Refl. Screen
A-D C2
UHF SWR (300-ohms) Under 1.9


Enlarge photo 6
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6
H+U Tapered Loop + Refl. Screen
A-D C2
UHF Impedance


Enlarge photo 7
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7
H+U Tapered Loop + Refl. Screen
A-D C2
Azimuthal Pattern at 470 MHz


Enlarge photo 8
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8
H+U Tapered Loop + Refl. Screen
A-D C2
Azimuthal Pattern at 530 MHz


Enlarge photo 9
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9
H+U Tapered Loop + Refl. Screen
A-D C2
Azimuthal Pattern at 590 MHz


Enlarge photo 10
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10
H+U Tapered Loop + Refl. Screen
A-D C2
Azimuthal Pattern at 650 MHz


Enlarge photo 11
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11
H+U Tapered Loop + Refl. Screen
A-D C2
Azimuthal Pattern at 698 MHz


Enlarge photo 12
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12
H+U Tapered Loop + Refl. Screen
A-D C2
Azimuthal Pattern at 758 MHz


Enlarge photo 13
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13
H+U Tapered Loop + Refl. Screen
A-D C2
Azimuthal Pattern at 806 MHz


Enlarge Microsoft Word Document 14
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DOC14
H+U Tapered Loop + Refl. Screen
A-D C2
4nec2 File Contains Summary of Dimensions


Enlarge photo 15
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15
H+U Tapered Loop + Refl. Screen
A-D C2 - Side View
[1 large square = 2.5 inches]


Enlarge photo 16
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16
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II - 3D View


Enlarge photo 17
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17
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II - Front View
[1 large square = 2.5 inches]


Enlarge photo 18
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18
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II - Top View
[1 large square = 2.5 inches]


Enlarge photo 19
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19
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
UHF Raw Gain = 9.4 to 10.1 dBi
UHF F/B & F/R Ratio Minimum = 17.9 dB


Enlarge photo 20
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20
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
UHF SWR (300-ohms) Under 2.5


Enlarge photo 21
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21
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
UHF Impedance


Enlarge photo 22
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22
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
Azimuthal Pattern at 470 MHz


Enlarge photo 23
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23
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
Azimuthal Pattern at 530 MHz


Enlarge photo 24
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24
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
Azimuthal Pattern at 590 MHz


Enlarge photo 25
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25
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
Azimuthal Pattern at 650 MHz


Enlarge photo 26
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26
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
Azimuthal Pattern at 698 MHz


Enlarge photo 27
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27
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
Azimuthal Pattern at 806 MHz


Enlarge Microsoft Word Document 28
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DOC28
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
4nec2 File Contains Summary of Dimensions


Enlarge Microsoft Word Document 29
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DOC29
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
Performance Summary per EVAL Function


Enlarge photo 30
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30
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II - Side View
[1 large square = 2.5 inches]


Enlarge photo 31
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31
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
Hi-VHF Raw Gain = 2.7 to 3.2 dBi
Hi-VHF F/B & F/R Ratio = 0.3 to 0.6 dB
A Bit More Gain Forward.


Enlarge photo 32
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32
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
Hi-VHF SWR (300-ohms) Under 2.4
Connected to UVSJ via 300:75-ohm Balun


Enlarge photo 33
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33
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
Hi-VHF Impedance


Enlarge photo 34
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34
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
Azimuthal Pattern at 174 MHz


Enlarge photo 35
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35
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
Azimuthal Pattern at 198 MHz


Enlarge photo 36
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36
H+U Tapered Loop + Refl. Screen + VHF Dipole
A-D C2-V Gen-I/II
Azimuthal Pattern at 216 MHz


Enlarge photo 37
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37
UHF Tapered Loop + NO Refl.
A-D C2 - 3D View


Enlarge photo 38
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38
UHF Tapered Loop + NO Refl.
A-D C2 - Front View
[1 large square = 1.25 inches]


Enlarge photo 39
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39
UHF Tapered Loop + NO Refl.
A-D C2 - Front View DETAIL
Feedpoint Gap = 0.1875-in [Marked with Red Circle]
[1 large square = 0.25 inches]


Enlarge photo 40
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40
UHF Tapered Loop + NO Refl.
A-D C2
UHF Raw Gain = 5.5 to 6.8 dBi


Enlarge photo 41
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41
UHF Tapered Loop + NO Refl.
A-D C2
UHF SWR (300-ohms) Under 3.2 at 470 MHz


Enlarge photo 42
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42
UHF Tapered Loop + NO Refl.
A-D C2
UHF Impedance


Enlarge photo 43
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43
UHF Tapered Loop + NO Refl.
A-D C2
Azimuthal Pattern at 470 MHz


Enlarge photo 44
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44
UHF Tapered Loop + NO Refl.
A-D C2
Azimuthal Pattern at 530 MHz


Enlarge photo 45
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45
UHF Tapered Loop + NO Refl.
A-D C2
Azimuthal Pattern at 590 MHz


Enlarge photo 46
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46
UHF Tapered Loop + NO Refl.
A-D C2
Azimuthal Pattern at 650 MHz


Enlarge photo 47
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47
UHF Tapered Loop + NO Refl.
A-D C2
Azimuthal Pattern at 698 MHz


Enlarge photo 48
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48
UHF Tapered Loop + NO Refl.
A-D C2
Azimuthal Pattern at 758 MHz


Enlarge photo 49
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49
UHF Tapered Loop + NO Refl.
A-D C2
Azimuthal Pattern at 806 MHz


Enlarge Microsoft Word Document 50
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DOC50
UHF Tapered Loop + NO Refl.
A-D C2
4nec2 File Contains Summary of Dimensions


Enlarge Microsoft Word Document 51
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DOC51
UHF Tapered Loop + NO Refl.
A-D C2
EVAL Summary of Performance


Enlarge photo 52
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52
UHF Tapered Loop + NO Refl.
A-D C2
Raw Gain vs Relem at 470 MHz
[Alum. Foil on Far Left, AWG-16 Far Right]


Enlarge photo 53
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53
UHF Tapered Loop + NO Refl.
A-D C2
Raw Gain vs Relem at 584 MHz


Enlarge photo 54
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54
UHF Tapered Loop + NO Refl.
A-D C2
Raw Gain vs Relem at 698 MHz


Enlarge photo 55
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55
UHF Tapered Loop + NO Refl.
A-D C2
SWR (300-ohms) vs Relem at 470 MHz
[Alum. Foil on Far Left, AWG-16 Far Right]


Enlarge photo 56
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56
UHF Tapered Loop + NO Refl.
A-D C2
SWR (300-ohms) vs Relem at 584 MHz


Enlarge photo 57
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57
UHF Tapered Loop + NO Refl.
A-D C2
SWR (300-ohms) vs Relem at 698 MHz


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