TopBand: High Angle vs. Low Angle
Earl W Cunningham
k6se@juno.com
Sun, 02 Aug 1998 22:50:32 EDT
Hi, Topbanders,
I've been following the high vs. low angle discussion with great
interest. To add some fuel to the fire, I used EZNEC to prepare the
following tables for those involved in the discussion to examine.
Heights for the inverted-vees are at the apex. The 50' high and 100'
high inverted-vees have their ends at 10' high.
The Beverages are 7' high with 50' of each end sloping to ground level.
450-ohm termination resistors were used in all cases, with no attempt to
optimize the Beverages.
The Pennant and Flag antennas are 20' high at the top and 6' high at the
bottom. They are identical to the descriptions I previously posted, with
no change in size or termination value over different types of ground.
The definitions for the various types of ground may be obtained from the
ARRL Antenna Book. The types of ground used when modeling extend from
beneath the antennas to the horizon.
When you look at the figures, it helps explain why stations on the Texas
Gulf coast and K0HA appear to do so well -- Those areas (and some others)
have their soil conductivity rated as "very good".
The gain figures are in dBi. "TOA" is the take-off angle of maximum
gain. The -3 dB points are the elevation angles where the gain is 3 dB
down from maximum. If the second -3 dB point is blank, that means that
even at 90 degrees the gain is less than 3 dB down.
All antennas were modeled at 1.830 mHz.
When reading or printing the charts, select a font that is equal-spaced
for all characters to maintain column integrity.
OVER "VERY POOR" GROUND:
ANT GAIN TOA -3 dB POINTS
------------- ----- ---- ------------
1/8-WAVE VERT -0.61 30.0 10.8 57.5
1/4-WAVE VERT -0.98 27.6 10.1 54.1
3/8-WAVE VERT -1.30 23.9 9.0 47.0
1/2-WAVE VERT -1.19 19.9 7.8 38.3
5/8-WAVE VERT 0.04 17.4 6.9 63.0
DIPOLE @ 50' 3.87 90.0 37.2 --
DIPOLE @ 100' 5.68 90.0 29.5 --
DIPOLE @ 150' 5.63 49.3 21.2 --
DIPOLE @ 200' 6.15 36.1 16.6 67.2
DIPOLE @ 250' 7.07 28.9 15.4 48.5
INV-V @ 50' 0.74 90.0 38.3 --
INV-V @ 100' 2.08 90.0 34.0 --
INV-V @ 150' 4.11 65.8 25.4 --
INV-V @ 200' 4.79 43.2 19.2 --
INV-V @ 250' 5.69 33.2 15.4 58.7
1000' BEV -7.84 27.0 10.8 43.2
500' BEV -10.54 42.1 15.6 67.0
OPTIMIZED EWE -26.38 38.6 12.8 79.2
K6SE PENNANT -37.59 38.4 12.7 79.7
K6SE FLAG -31.80 38.6 12.7 79.6
OVER "POOR" GROUND:
ANT GAIN TOA -3 dB POINTS
------------- ----- ---- ------------
1/8-WAVE VERT 0.53 27.5 9.0 55.9
1/4-WAVE VERT 0.32 25.3 8.5 52.4
3/8-WAVE VERT 0.16 21.9 7.7 45.3
1/2-WAVE VERT 0.26 18.1 6.7 35.8
5/8-WAVE VERT 0.76 14.6 5.7 29.5
DIPOLE @ 50' 4.38 90.0 39.3 --
DIPOLE @ 100' 6.25 90.0 32.1 --
DIPOLE @ 150' 5.94 53.1 23.8 --
DIPOLE @ 200' 6.31 38.0 17.5 71.8
DIPOLE @ 250' 7.24 30.0 14.2 50.1
INV-V @ 50' 1.11 90.0 40.2 --
INV-V @ 100' 2.81 90.0 36.3 --
INV-V @ 150' 4.64 76.8 27.7 --
INV-V @ 200' 5.01 46.1 20.4 --
INV-V @ 250' 5.81 34.7 16.1 61.5
1000' BEV -8.11 25.6 9.3 42.6
500' BEV -11.35 40.3 13.1 66.3
OPTIMIZED EWE -24.44 38.6 10.6 78.0
K6SE PENNANT -36.64 35.3 10.5 77.7
K6SE FLAG -30.85 35.3 10.5 77.5
OVER "GOOD" GROUND:
ANT GAIN TOA -3 dB POINTS
------------- ----- ---- ------------
1/8-WAVE VERT 1.57 24.6 7.3 54.0
1/4-WAVE VERT 1.42 22.7 6.9 50.3
3/8-WAVE VERT 1.31 19.6 6.3 43.1
1/2-WAVE VERT 1.36 16.1 5.6 33.4
5/8-WAVE VERT 1.35 12.6 4.7 24.7
DIPOLE @ 50' 5.41 90.0 40.7 --
DIPOLE @ 100' 6.82 90.0 33.7 --
DIPOLE @ 150' 6.27 55.3 23.8 --
DIPOLE @ 200' 6.53 39.0 18.1 73.7
DIPOLE @ 250' 7.50 30.6 14.6 50.8
INV-V @ 50' 2.28 90.0 41.6 --
INV-V @ 100' 3.73 90.0 36.3 --
INV-V @ 150' 5.16 88.3 29.3 --
INV-V @ 200' 5.27 47.5 21.2 --
INV-V @ 250' 6.02 35.5 16.7 62.6
1000' BEV -9.02 24.5 7.8 42.6
500' BEV -12.88 39.7 10.8 66.9
OPTIMUM EWE -24.68 31.9 8.4 76.2
K6SE PENNANT -35.76 31.3 8.3 75.3
K6SE FLAG -29.99 31.5 8.3 75.1
OVER "VERY GOOD" GROUND:
ANT GAIN TOA -3 dB POINTS
------------- ----- ---- ------------
1/8-WAVE VERT 3.11 18.7 4.0 50.4
1/4-WAVE VERT 3.16 17.2 3.9 46.4
3/8-WAVE VERT 3.36 14.9 3.6 39.2
1/2-WAVE VERT 3.31 12.3 3.3 30.2
5/8-WAVE VERT 4.21 9.7 2.9 21.4
DIPOLE @ 50' 6.80 90.0 42.3 --
DIPOLE @ 100' 7.52 90.0 35.9 --
DIPOLE @ 150' 6.67 59.4 25.4 --
DIPOLE @ 200' 6.72 40.7 19.0 80.1
DIPOLE @ 250' 7.69 31.6 15.2 52.3
INV-V @ 50' 4.09 90.0 43.1 --
INV-V @ 100' 4.98 90.0 39.7 --
INV-V @ 150' 5.84 88.3 31.6 --
INV-V @ 200' 5.57 50.4 22.5 --
INV-V @ 250' 6.18 36.9 17.4 65.5
1000' BEV -13.04 25.2 5.0 45.2
500' BEV -17.07 46.0 8.3 71.9
OPTIMUM EWE -23.18 25.0 4.4 74.2
K6SE PENNANT -34.52 23.6 4.4 70.6
K6SE FLAG -28.74 23.6 4.4 70.5
OVER SALT WATER:
ANT GAIN TOA -3 dB POINTS
------------- ----- ---- ------------
1/8-WAVE VERT 4.54 8.0 0.5 45.1
1/4-WAVE VERT 4.81 7.4 0.5 40.8
3/8-WAVE VERT 5.33 6.4 0.4 33.8
1/2-WAVE VERT 6.26 5.4 0.4 25.8
5/8-WAVE VERT 7.41 4.3 0.4 18.2
DIPOLE @ 50' 8.07 90.0 43.3 --
DIPOLE @ 100' 7.99 90.0 37.3 --
DIPOLE @ 150' 6.95 63.2 26.5 --
DIPOLE @ 200' 6.84 42.0 18.6 --
DIPOLE @ 250' 7.77 32.4 15.6 53.6
INV-V @ 50' 6.23 90.0 44.0 --
INV-V @ 100' 5.96 90.0 40.8 --
INV-V @ 150' 6.30 90.0 33.1 --
INV-V @ 200' 5.78 52.6 23.4 --
INV-V @ 250' 6.27 38.0 17.9 68.1
1000' BEV -22.02 43.2 28.2 54.6
500' BEV -22.35 64.1 43.3 81.5
OPTIMUM EWE -23.35 10.3 0.5 62.6
K6SE PENNANT -33.39 10.2 0.5 64.3
K6SE FLAG -27.60 10.1 0.5 64.3
BTW, I have my first Pennant installed, pointing at 53 degrees (directly
at K6NDV about 4.5 miles away). Last night I got to do a few comparisons
on stations to the east and northeast. It appears to have a slightly
better S/N than my 2-el vertical transmitting arrays in that direction on
160m and 80m. It even compares favorably on 40m vs. my 2-el short Yagi
at 75'.
With my new FT-1000MP there seems to be no need for additional
preamplification, even though the Pennant models 6 s-units down from an
isotropic.
This coming week I hope to get another Pennant up in the exact opposite
direction and then do some quick-switch F/B comparisons.
73, de Earl, K6SE
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