[TowerTalk] 160 vertical question (Top Hat)

[Grant Saviers]

Top loading is a winner to increase antenna efficiency.  I agree that 
EZNEC is essential since umbrella (slanted) wires have less effect than 
a flat top hat and also tend to shield the antenna a bit.  The model 
needs the segments aligned in each element.  Trig or use AutoEZ to 
figure that out.

There are a couple of articles worth reading on Rudy Severns web site 
antennasbyn6lf.com

This article is for top loaded verticals for the new LF bands but covers 
the principles well
http://rudys.typepad.com/files/chapter-3--1.pdf

My T is 10' at the base elevated radials, 85' to the top, and 33' or so 
each side, resonates at 1820, 25 ohms.

Grant KZ1W


On 2/3/2018 17:44 PM, Richard (Rick) Karlquist wrote:
> You should really model this on EZNEC.
> Having done this many times, I can say
> that the length of the vertical plus the
> length of one of the top wires should be
> about 120 feet to hit exact 1830 resonance
> without a loading coil.  However,
> there is absolutely no compelling reason why
> this is necessary.  A loading/matching coil
> is far more convenient if you keep the wire
> length to 25 feet.  Therefore, it should
> never be necessary to put it up and down a
> bunch of times to get it "just right".  There
> is no "just right" with respect to the antenna
> proper.  Use the taps on the coil to do the trimming
> to make the system just right.  This has been
> discussed many times on this reflector.
>
> Rick N6RK
>
> On 2/3/2018 5:20 PM, Bill via TowerTalk wrote:
>>
>> Planning on putting up a 160 vertical, but of course a 1/4 wave 
>> vertical is out of the question here in HI since we have a height 
>> limitation.
>>   Here's the question:  I'm putting up around 50 feet of 3 inch 
>> aluminum tubing  (left over from various antenna takedowns).  I plan 
>> on putting up on top of that around another 10 or 15 feet of smaller 
>> diameter stinger for a total height of around 60-65 feet.  I 
>> obviously need to make up for the lack of height and I was planning 
>> on making a top hat of four wires coming down from the top of the 
>> antenna at around a 45 degree angle.  The problem is how long to make 
>> each of those wires.  My guess is around 25 feet based on my past 
>> experience in making Tee-topped 80 meter verticals.  However, it is 
>> only a guess and I don't feel like yanking the 3 inch pipe up and 
>> down a bunch of times to get it just right.
>>   I know some trimming will be necessary since this is not an exact 
>> science.  I just need an educated guess for where to start with the 
>> length.  Any ideas?
>>   Bill K4XS/KH7XS
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