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mclapp's M4 (10.0x9.5) 4-Bay - NO Refl. (6 Aug 2012)Somewhat larger Super M4 (10.0" x 9.5") 4-Bay Bowtie, per mclapp's drawings, analyzed using 4nec2:
http://m4antenna.eastmasonvilleweather.com/Drawings/PDF%20Drawings.html
See 4nec2 File for dimensional details.
BowLength = 10.0-in (AWG8), Bowtie Spacing = 9.5-in, Tine Separation = 5.5-in.
Feedline Separation = 1.25-in, with 1.0-in at Crossover (AWG10).
Center of Crossover 3.125-in from Center of Outer Bowties.
Small increase in UHF Gain, but Hi-VHF Gain remains same as in 9.5" x 9.0" version. |
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UHF Kosmic SuperQuad (9.75x9.5) NO Refl. (2 Mar 2010)Kosmic SuperQuad 4-Bay (if NO Reflector) analyzed using 4nec2.
Dimensions from EV's Kosmic SuperQuad thread:
http://www.dtvusaforum.com/dtv-hdtv-reception-antenna-discussion/8629-kosmic-antennas-superquad-4-bay-bowtie.html
BowLength = 9.75-in (AWG8), Bowtie Spacing = 9.5-in, Tine Separation = 5.0-in. Simulated SOURCE wire.
Feedline Separation = 1.5-in, except 1.25 at Crossovers (AWG8). Crossovers = 4.75-in from Outer Bowties. |
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mclapp's M4 (9.5x9.0) 4-Bay - NO Refl. (6 Sep 2009)mclapp's M4 (9-5x9) Super-4-Bay Bowtie, with No Reflector, optimized for New UHF Band (Ch14-51):
http://m4antenna.eastmasonvilleweather.com/Computer%20models/Computer%20models.html
http://m4antenna.eastmasonvilleweather.com/Drawings/PDF%20Drawings.html
http://www.youtube.com/watch?v=M8jsDxNgHn4
FYI: Performance comparisons (No Reflectors):
http://www.frontiernet.net/~mclapp/Antennas/4baystuff/no%20reflector%20antenna%20test.GIF
And various with Reflectors:
http://www.frontiernet.net/~mclapp/Antennas/plots/4%20bay%20compare11-23-08.xls
BowLength = 9.5-in (AWG8), Bowtie Spacing = 9.0-in, Tine Separation = 5.5-in.
Feedline Separation = 1.25-in, including at Crossover (AWG10). Simulated Balun with 0.44-in SOURCE wire.
Gain and SWR are Good for entire New UHF Band and also Hi-VHF Ch7-13.
Sweeping Bowties Forward was ineffective in increasing Gain, other than a small increase above Ch51. |
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mclapp 9.5x9.0x8.5 Super-4-Bay - NO Refl (27Feb2009)mclapp's 4-Bay Bowtie "9-5x9" (actually 9.5x9.0x8.5), with No Reflector, optimized for New UHF Band (Ch14-51):
http://www.frontiernet.net/~mclapp/Antennas/Computer%20Models/
Filename run here is "4bay bow 9-5x9.nec"
Note that mclapp's posted 4nec2 file above has 8.5 rather than 9.0-in Inner-Outer Bowtie Separation shown here:
http://www.frontiernet.net/~mclapp/Antennas/diagrams.html
FYI: Performance comparisons (No Reflectors):
http://www.frontiernet.net/~mclapp/Antennas/4baystuff/no%20reflector%20antenna%20test.GIF
And various with Reflectors:
http://www.frontiernet.net/~mclapp/Antennas/plots/4%20bay%20compare11-23-08.xls
BowLength = 9.5-in, Inner-Inner Bowtie Spacing = 9.0-in, Inner-Outer Bowtie Spacing = 8.5, Tine Separation = 5.5-in.
Feedline Separation = 1.25-in, including at Crossover. Simulated Balun with 0.44-in SOURCE wire.
Gain and SWR are Good for entire UHF Band and also Hi-VHF Ch10-13.
Higher SWR on Ch7-9 will reduce Net Gain but may still be usable.
CONCLUSION: (9.5x9.0x8.5) has more Gain than M4 (9.5x9.0) on Ch52-69, but Hi-VHF SWR is worse.
EDIT (23Aug2009): Clarified difference between mclapp's 4nec2 file run here (9.5x9.0x8.5) versus his
posted dimensions for a 9.5x9.0(x9.0) design. |
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CM4221 Actual Measurements - if NO Refl (23Aug2009)CM4221 per Actual Measurements analyzed using 4nec2 (verified against a photo posted by mclapp):
http://www.frontiernet.net/~mclapp/Antennas/CM4221/CM4221%20front.jpg
BowLength = 8.5-in, Bowtie Spacing = 8.9-in, Tine Separation = 5.25-in. All AWG8.
Feedline Separation = 1.4-in, with 0.8-in at Crossover. All AWG8 wire size (0.125" O.D.).
Center of Crossovers 2.75-in from Center of Outer Bowties. |
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CM4221a.ez 4-Bay Bowtie - if NO Refl (26 Feb 2009)CM4221a.ez EZNEC file 4-Bay Antenna with Reflector removed. Illustrates one of the BETTER 4-Bay Antenna designs.
Dimensions from Ken Nist's cm4221a.ez NEC file are SAME as HALF of cm4228a.ez (Demi-CM4228).
Long feed (simulating twin-lead?) was changed to simple Balun Source (BS) or simple Wire Source (WS) to fix VHF AvgGainTest.
BowLength = 7.8-in, Bowtie Spacing = 8-in, Tine Separation = 5.5-in.
Feedline Separation = 1.25-in, with 0.8-in at Crossover.
In fol. 4nec2 simulation, per Ken Nist's EZNEC file, a simple 1.25-in SOURCE wire (SW) interconnects the feedlines.
Runs with a Simulated Balun SOURCE (BS) feed yield very similar results.
UHF Raw Gain increases with frequency from 6.5 dBi to 12 dBi. SWR under 5.0 at low freqs, decreasing at highest freqs to 1.5.
VHF Raw Gain is constant 4.1 dBi. EXCESSIVE SWR decreases with frequency. Ch13 may be usable but ineffective on Ch7-12. |
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UTube 4-Bay Bowtie - NO Reflector (27 Jan 2009)UTube 4-Bay Bowtie Antenna (without Reflector) per Maker Workshop UTube video and makezine.tv pdf file:
http://www.youtube.com/watch?v=0rDPZZzIXIc and http://cachefly.oreilly.com/make/television/04/DTV_Antenna_FINAL.pdf
They said to use a 3"x20" mounting board, with just over 2" Feedline Separation. Coat Hangers are cut down to 8", but
extend inside feedline, so (after bend loss) are 7.5" to 7.75" whiskers. Bowtie Spacings = 5.75" and Tine Spacing = 3".
Nearly identical (earlier?) Make:TV pdf file I found via Google search is here: http://current.org/ptv/ptv0821make.pdf
Note John Park points to a commercial 4-Bay Bowtie Antenna (with Reflector) and incorrectly calls it a "Hoverman".
This error is repeated in both of the above pdf files.
Most popular UTube "Coat Hanger HDTV Antenna", is a 4-Bay Bowtie without Reflector (1+ Million views!!!) from babblin5:
http://www.youtube.com/watch?v=EWQhlmJTMzw
He says to use a 2.5"x20" mounting board, with a smaller 1.5" Feedline Separation.
Coat Hangers start out as 14", so (after bend loss) are shorter 6.75" whiskers.
Uses same 5.75" Bowtie Spacings and 3" Tine Spacing as above.
So "UTube TV Antenna" dimensions vary as follows: BowLength = 6.75 to 7.75-in (after bend), Bowtie Spacing = 5.75-in.
Tine Separation = 3-in, Feedline Separation = 1.5 to 2.0-in, with only about 0.15-in at Crossover (wire center to wire center).
Crossover is equidistant between Bowties, unlike other 4-Bays. Moving Crossover closer to the end yields better Gain and SWR.
In fol. 4nec2 simulation, a simulated SOURCE Wire feeds the antenna, with SOURCE wire radius chosen for best UHF & VHF Average Gain Test.
Poor UHF Raw Gain below 520 MHz (Ch14-21). And very poor SWR mid-band reduces Net Gain.
Hi-VHF Raw Gain is constant 3.2 dBi. However VERY EXCESSIVE SWR on Ch7-13, although Ch13 isn't as bad as lower channels.
RECOMMENDATION: START OVER WITH A DIFFERENT DESIGN WITH MORE SEPARATION BETWEEN BOWTIES.
EDIT (24Aug2009): Error in 4nec2 model calculations resulted in whiskers being 1.4-in shorter than specified.
New results replace old charts. Low Freq UHF Gain loss is still present, but not as severe. EXCESSIVE SWR remains a big problem. |
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