[TowerTalk] Stacking Distance for M2'd 6m7JHV?

[Jim Lux]

At 05:18 PM 7/12/2004 -0700, Jim Lux wrote:
>At 04:35 PM 7/12/2004 -0700, David O Hachadorian wrote:
>
>
>>On Mon, 12 Jul 2004 15:02:34 -0500 "Chuck Dietz" <w5pr at swbell.net>
>>writes:
>> >  Spacing does not really affect takeoff angle.  Takeoff angle is
>> > totally
>> > dependent upon height above ground.  If you have optimum spacing,
>> > the
>> > takeoff angle will be the same as an antenna mounted 1/2 way between
>> > the
>> > stacked antennas.
>> >
>> > Chuck W5PR
>> >
>> >
>
>It's not the average of the two antennas..
>
>Using HFTA
>
>I just ran a pair of 3element antennas for 20m over flat ground
>The main lobe for 30ft is about 30 deg
>for 60ft it's about 16 deg
>for the pair it's at 20 deg.
>
>Changing to 6 elements, it's much the same:
>30 - 28 deg
>60' - 16 deg
>pair - 19 deg
>
>Even going to 50 MHz
>The 30ft antenna has lobes at 9.5 and 28.5
>The 60ft @ 4.5,14, 25
>the pair a big lobe at 5.5, two small lobes at 15.5, 22.5, then another 
>big lobe at 33.5
>
>
>Something is odd though..
>The results for the latter are the same regardless of the ground type. 
>perhaps it's because of the fairly high gain antennas..

Mis-read Chuck's original statement.. However, running the simulation with 
an antenna at 45 feet,
  at 14.2 MHz, 3 element, 45' lobe at 21.5deg
Likewise, changing to 50MHz, the main lobe is at 6.25 deg...
And, of course, the sidelobes (which are a LOT bigger with the single 
antenna)are not where the sidelobes of the pair are.