[TowerTalk] Trapped Tribanders Turned Vertical

[Joe Subich, W4TV]

> 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 
  





> -----Original Message-----
> From: towertalk-bounces at contesting.com 
> [mailto:towertalk-bounces at contesting.com] On Behalf Of K4SAV
> Sent: Wednesday, June 20, 2007 12:26 AM
> To: towertalk at contesting.com
> Subject: Re: [TowerTalk] Trapped Tribanders Turned Vertical
> 
> 
> If the trees are so close that it turns vertically but not 
> horizontally, 
> that will only last about 3 months, then he won't be able to turn it 
> mounted vertically.
> 
> Besides if the antenna is very low, mounting it vertically 
> will loose a 
> lot of gain.  For example, over average ground a 3 element 
> Yagi at 40 ft 
> might produce 12 dBi gain at 24 degrees take-off angle.  The same 
> antenna turned vertically will produce 6 dBi gain at 12 degrees 
> elevation (or 3.3 dBi at 24 degrees elevation).  The 
> vertically mounted 
> antenna will have a much wider lobe in the azimuth direction 
> (about 50% 
> wider).
> 
> The higher the antennas are, the less difference in gain 
> there will be 
> between mounting vertically and horizontally.  If it is over 
> salt water, 
> the answer will be considerably different.
> 
> Then there is the mast interference problem to solve.
> 
> Jerry, K4SAV
> 
> Robert Pack, NX5M wrote:
> 
> >The only thing he is going to gain is being able to put 
> something up that he 
> >can turn.  He cannot go high and he has tree issues that 
> prevent him from 
> >turning it if it is horizontal.
> >
> >----- Original Message ----- 
> >From: "Mark Robinson" <markrob at mindspring.com>
> >To: "Robert Pack, NX5M" <nx5m at txcyber.com>; 
> <towertalk at contesting.com>
> >Sent: Tuesday, June 19, 2007 7:41 PM
> >Subject: Re: [TowerTalk] Trapped Tribanders Turned Vertical
> >
> >
> >  
> >
> >>What does he hope to gain by mounting the tribander vertically?
> >>
> >>
> >>Mark N1UK G3ZZM
> >>
> >>
> >>----- Original Message ----- 
> >>From: "Robert Pack, NX5M" <nx5m at txcyber.com>
> >>To: <towertalk at contesting.com>
> >>Sent: Tuesday, 19 June, 2007 8:00 PM
> >>Subject: [TowerTalk] Trapped Tribanders Turned Vertical
> >>
> >>
> >>    
> >>
> >>>Without going into great detail with the reason this 
> question is being 
> >>>asked......local guy wants to put a tribander up (an A3 I 
> think) and 
> >>>wants to mount it vertically.  He asked me what I thought 
> about it.  My 
> >>>first thought was water getting into the traps and not 
> draining out, or 
> >>>draining out too slow.
> >>>I have never seen a vertically mounted tribander (other 
> than triband or 
> >>>better verticals).  I will admit that I have never looked 
> closely at a 
> >>>trapped vertical so I do not know if there is anything 
> different in the 
> >>>sealing of the traps or not.  Is there?
> >>>
> >>>Could this fellow actually put his three element tribander 
> vertical? 
> >>>Should he seal the top ends of the traps and maybe put 
> small pin holes on 
> >>>the bottom ends so water can drip out?  Any electrical or 
> structural 
> >>>issues that come to mind?
> >>>
> >>>I will print and pass along all replies.
> >>>
> >>>Thanks.
> >>>Bob NX5M
> >>>_______________________________________________
> >>>
> >>>
> >>>
> >>>      
> >>>
> >  
> >
> 
> _______________________________________________
> 
> 
> 
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