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UHF H2 (11x12) 2-Bay Bowtie - NO Refl (8 Feb 2015)UHF H2 (11x12) 2-Bay Bowtie with No Reflector, OPTIMIZED for New UHF Band using nikiml's
Python Optimization Scripts. Charts show significant improvement of H2 vs either M2 version.
Overall Dimensions: 20.0-in H x 21.75-in W
UHF Raw Gain = 7.3 to 10.3 dBi with SWR (300-ohms) under 3.0 (Good).
Hi-VHF Raw Gain = 2.4 to 2.8 dBi with SWR (300-ohms) = 12.4 to 6.7 is Excessive.
OPTIMIZED DIMENSIONS:
BowLen = 11.0 = Bowtie Whisker Half-Length,
ZBowII = 12.0 = Distance between the Centers of the two Bowties,
TineSep = 8.0 = Bowtie Tine Separation,
FedSep = 1.25 = Separation (in inches) between two FEEDLINE wires. |
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 | 2.
UHF M2 2-Bay Bowtie - NO Reflector (20 Apr 2010)UHF M2 (10.0x9.5) 2-Bay Bowtie with No Reflector analyzed using 4nec2. Dimensions for mclapp's M2 are half of an M4.
Height=14-inches, Width=20-inches.
UHF Raw Gain = 5.7 to 9.7 dBi and SWR (300-ohms) under 3.2 [FAIR].
Hi-VHF Raw Gain = 2.2 to 2.5 dBi and SWR (300-ohms) = 13 to 7 [EXCESSIVE].
Quasi-Optimum sizes for ALL AWG10 wire sizes:
BowLength=10.0", BowSpacing=9.5", TineSpacing=5.0",
FeedlineSeparation =1.5" and ALL AWG10 wire size.
Good UHF Band Gain, although SWR increases at higher frequencies.
Hi-VHF Gain about same as a Dipole, but SWR is Excessive.
BTW: M2 (9.5x9.0) Raw Gain Curve was NOT well matched to the NEW UHF Band, extending well beyond
Ch51 (698 MHz) and hence less Gain was available on the lower Channels, see charts at the bottom. |
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 | 3.
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 user "freezer" on the WallTenna.
Yes, it's a 2-Bay Bowtie....but it's WAY TOO SMALL: http://www.walltenna.com
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:
UHF Raw Gain = 3.5 to 7.9 dBi (Very Poor for 2-Bay, esp. lower Freqs) with SWR (300-ohms) under 2.3.
Hi-VHF Raw Gain = 2.0 to 2.2 dBi with SWR (300-ohms) = 28 to 15 [Excessive].
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2) Add Whisker Extensions to improve UHF performance:
UHF Raw Gain = 4.8 to 8.8 dBi (1.3 to 1.9 dB Improvement) with SWR (300-ohms) under 2.9.
Hi-VHF Raw Gain = 2.1 to 2.3 dBi with SWR (300-ohms) = 14 to 7.5 [Excessive].
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3) Add Co-Planar Rectangular Loop Resonator (23.5-in H x 24-in W) to improve Hi-VHF Performance.
UHF Raw Gain = 7.1 to 9.6 to 8.7 dBi (2.6 to 2.0 to 0.8 dB Improvement) with SWR (300-ohms)
Under 3.3 (a Bit Higher than "As Built").
Hi-VHF Raw Gain = 3.4 to 3.7 dBi (1.4 to 1.2 dB Better than "As Built") with SWR (300-ohms) under 2.9
(Huge Improvement).
ERRATA (18Jan2016): Scale label was incorrect in Slide #38. Should be 2.5-in vice 1.25-in. |
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