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UHF CM4248 Folded Dipole Bowtie (ONLY)
UHF CM4248 Folded Dipole Bowtie (ONLY) analyzed using 4nec2.

Dimensions from cm4248 4nec2 file posted by 300ohm, derived from Ken Nist's cm4248a.ez file.
Also found in other Channel Master antennas.

CM4248's Bowtie has two rearward facing stubs, the first results are for this "As-Built" configuration.
Note that the stubs are effectively EXTENDING the overall length of the Bowtie Elements, resulting in
a NARROWER Bowtie, which has LOWER Raw Gain than for a Bowtie without the stubs (see next analysis).

Removing the stubs shifted the frequency of operation significantly upwards (see Wideband Charts at bottom),
which was countered by Rescaling LARGER by the factor 1.38, as shown in the second set of results.

This comparison emphasizes the importance of MODELING to determine results,
rather than expecting Wideband Bowties to follow a 1/2-wavelength
or full-wavelength or some other sort of commonly encountered "Design Rule".
Date(s): 17 Jan 2012. Album by holl_ands. 1 - 29 of 29 Total. 12523 Visits.
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1
CM4248 Folded Dipole Bowtie, As-Built
3D View


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2
CM4248 Folded Dipole Bowtie, As-Built
Front View
[1 big box = 1.25-inches]


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3
CM4248 Folded Dipole Bowtie, As-Built
Top View
[1 big box = 1.25-inches]


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4
CM4248 Folded Dipole Bowtie, As-Built
UHF Raw Gain = 1.9 to 2.6 dBi


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5
CM4248 Folded Dipole Bowtie, As-Built
UHF SWR (300-ohms) Under 2.6


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6
CM4248 Folded Dipole Bowtie, As-Built
UHF Impedance


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7
CM4248 Folded Dipole Bowtie, As-Built
Azimuthal Pattern at 470 MHz


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8
CM4248 Folded Dipole Bowtie, As-Built
Azimuthal Pattern at 590 MHz


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9
CM4248 Folded Dipole Bowtie, As-Built
Azimuthal Pattern at 698 MHz


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10
CM4248 Folded Dipole Bowtie, As-Built
Azimuthal Pattern at 758 MHz


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11
CM4248 Folded Dipole Bowtie, As-Built
Azimuthal Pattern at 806 MHz


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12
CM4248 Folded Dipole Bowtie, As-Built
Side View
[1 big box = 0.5-inches]


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13
CM4248 Folded Dipole Bowtie, No Stubs, Rescaled
3D View


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14
CM4248 Folded Dipole Bowtie, No Stubs, Rescaled
Front View
[1 big box = 1.25-inches]


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15
CM4248 Folded Dipole Bowtie - No Stubs, Rescaled
Top View
[1 big box = 1.25-inches]


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16
CM4248 Folded Dipole Bowtie, No Stubs, Rescaled
UHF Raw Gain = 2.1 to 3.9 dBi


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17
CM4248 Folded Dipole Bowtie, No Stubs, Rescaled
UHF SWR (300-ohms) Under 1.5


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18
CM4248 Folded Dipole Bowtie, No Stubs, Rescaled
UHF Impedance


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19
CM4248 Folded Dipole Bowtie, No Stubs, Rescaled
Azimuthal Pattern at 470 MHz


Enlarge photo 20
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20
CM4248 Folded Dipole Bowtie, No Stubs, Rescaled
Azimuthal Pattern at 590 MHz


Enlarge photo 21
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21
CM4248 Folded Dipole Bowtie, No Stubs, Rescaled
Azimuthal Pattern at 698 MHz


Enlarge photo 22
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22
CM4248 Folded Dipole Bowtie, No Stubs, Rescaled
Azimuthal Pattern at 758 MHz


Enlarge photo 23
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23
CM4248 Folded Dipole Bowtie - No Stubs
Azimuthal Pattern at 806 MHz


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24
CM4248 Folded Dipole Bowtie, No Stubs, Rescaled
Side View
[1 big box = 0.5-inches]


Enlarge Microsoft Word Document 25
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DOC25
CM4248 Folded Dipole Bowtie, As-Built
4nec2 File


Enlarge Microsoft Word Document 26
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DOC26
CM4248 Folded Dipole Bowtie, No Stubs, Rescaled
4nec2 File


Enlarge Microsoft Word Document 27
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DOC27
CM4248 Folded Dipole Bowtie, No Stubs
4nec2 File - Prior to Rescale


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28
CM4248 Folded Dipole Bowtie, No Stubs
4nec2 File - Prior to Rescale
Wideband Raw Gain shifts UPWARD in Frequency
OK Above 650 MHz


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29
CM4248 Folded Dipole Bowtie, No Stubs
4nec2 File - Prior to Rescale
Wideband SWR (300-ohms) also shifts UPWARD
OK Above 650 MHz


 
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