K4SAV wrote:
The higher the antennas are, the less difference in gain there will be
between mounting vertically and horizontally.
W4TV wrote:
Not true ... the vertical beam will always miss the "ground
gain" and will lag the horizontal antenna by three to six dB.
------------------------
Well, my original statement is not 100% true for all heights, and
neither is yours. Here are some EZNEC numbers for a three element Yagi
turned either vertically of horizontally.
Height ___ Horz Antenna ______ Vert Antenna ____ Gain Difference
20 ______ 9.6 dBi at 36 deg ___ 4.8 at 17 deg ______ 4.8 dB
30_______11 dBi at 28 deg _____ 5.7 dBi at 15 deg __ 5.3 dB
35 _____ 11.6 dBi at 25 deg ____5.9 dBi at 13 deg __ 5.7 dB
40 _____ 11.9 dBi at 23 deg ___ 6 dBi at 12 deg ____ 5.9 dB
80 _____ 12.7 dBi at 12 deg ___ 8 dBi at 9 deg _____ 4.7 dB
100 ____ 12.9 dBi at 10 deg ___ 8.8 dBi at 8 deg ___ 4.1 dB
120 ____ 12.9 dBi at 8 deg ____ 9.4 at 7 deg _______ 3.5 dB
150 ____ 13 dBi at 7 deg ______ 10.1 dBi at 6 deg __ 2.9 dB
200 ____ 13.2 dBi at 5 deg ____ 10.8 dBi at 5 deg __ 2.4 dB
300 ____ 13.1 dBi at 3 deg ____ 11.6 dBi at 3 deg __ 1.5 dB
When a horizontal antenna is placed very close to the ground, like 35
feet or less for a 20 meter antenna, the ground loss for the horizontal
antenna increases dramatically making my original statement not exactly
accurate. However, above about 40 feet, the gain difference between a
horizontal and vertically mounted antenna steadily decreases.
Jerry, K4SAV
Joe Subich, W4TV wrote:
>>The higher the antennas are, the less difference in gain
>>there will be between mounting vertically and horizontally.
>>
>>
>
>Not true ... the vertical beam will always miss the "ground
>gain" and will lag the horizontal antenna by three to six dB.
>Over salt water the vertical beam will have more gain at
>lower take off angles but its maximum gain will never equal
>that of the same beam mounted horizontally.
>
>A good frequency for comparison is 10 meters as the height
>required for a horizontal antenna to have a take off angle
>similar to that of the vertical antenna becomes reasonable.
>A vertical dipole at 55' (center) over perfect ground (salt
>water) has a peak gain of 4.13 dB at 7 degrees. A horizontal
>dipole at 55' has a peak gain of 8.08 dBi at 9 degrees (7.63
>dBi at 7 degrees). Move the antennas to 70 feet and the
>gains are 4.71 dBi for the vertical dipole and 7.92 dBi for
>the horizontal dipole (at 7 degrees).
>
>73,
>
> ... Joe, W4TV
>
>
>
>
>
>
>
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