Towertalk
[Top] [All Lists]

[TowerTalk] Modeling

 To: [TowerTalk] Modeling nielsen@oz.net (Bob Nielsen) Tue, 5 Feb 2002 10:12:14 -0800
 ```On Mon, Feb 04, 2002 at 09:08:30PM -0800, Al Williams wrote: > > There is a reason that 12M Yagi's interact with > > tribanders and 10 and / or 15 meter beams... > What is the mechanism that causes an element longer than the driven > element to re-radiate in the same direction as an element shorter > than the driven element but on the opposite side? > > Please, answer not too heavy in math, physics, and geometry but also > not simplistic. Fairly simplified version: Each element radiates in both directions, but the resulting pattern is the vector sum of the radiation of all of the elements. This is dependent on the location of the elements and the phase of the radiation from each element. A parasitic element radiates because the radiation from the driven element induces a current in the parasitic element. This is known as mutual coupling. If the parasitic element is longer than resonant length the phase of the re-radiated pattern from that element is such that the vector sum of the patterns of it and the driven element will add in the direction away from the parasitic element (hence the term reflector) and subtract in the direction toward the parasitic element. Likewise, if the parasitic element is shorter than resonance the patterns will add in the direction of the parasitic element (director). Bob, N7XY ________________________________________________________________________ Where do you get ICE bandpass filters & beverage matching boxes? The same place that pays for the hosting of this list: The eHam Store. Order online at http://store.eham.net. ----------------------------------------------------------------------- ----- FAQ on WWW: http://www.contesting.com/FAQ/towertalk Submissions: towertalk@contesting.com Administrative requests: towertalk-REQUEST@contesting.com Problems: owner-towertalk@contesting.com ```
 Current Thread [TowerTalk] Modeling, (continued) [TowerTalk] Modeling, Guy Olinger, K2AV [TowerTalk] Modeling II, Robert Shohet [TowerTalk] Modeling, David L. Thompson [TowerTalk] Modeling, Bill Hider (N3RR) [TowerTalk] Modeling, Robert Shohet [TowerTalk] Crank up tower climbing safety, Michael Watts [TowerTalk] Modeling, K3BU@aol.com [TowerTalk] Modeling, Robert Shohet [TowerTalk] Modeling, n4kg@juno.com [TowerTalk] Modeling, Al Williams [TowerTalk] Modeling, Bob Nielsen <= [TowerTalk] Modeling, Tom Rauch