[TowerTalk] t type antenna

[Richard Karlquist]

I once constructed an emergency 160 meter vertical out of a 60 foot mast
made of aluminum irrigation pipe along with a top hat consisting of two
120 foot "umbrella wires" that I cut to length to make resonance at
1830.  I guess you could call that a "240 foot" top hat.  It of course
had a very low drive impedance that I matched with a shunt capacitor. 
It worked pretty well over the limited bandwidth that was possible,
because I had it over a very effective ground screen.  This sort of
thing also has a 2nd harmonic resonance in the 80 meter band, but it is
"voltage driven" meaning the drive impedance is 1000's of ohms.  I have
also put that kind of antenna on the air on 80 meters using some
breadslicer air variables.  Nothing mysterious about these antennas.

---
Rick Karlquist
N6RK 

On 2022-12-19 09:01, john at kk9a.com wrote:

> I was also trying to understand the 300 foot top hat. I have never seen that even on top band.  It would be easy to model to see where it's resonant.
> 
> John KK9A
> 
> Stan Stockton K5GO wrote:
> 
> 350 feet is about 5 quarter wavelengths at 3.8 MHz.  Quarter wavelength is about 65 feet or so.  If that thing is really 350 feet long you should see resonance at about 700 kHz, in addition to every odd multiple of a quarter wavelength.  Was there a typo or is this really an inverted L that is 350 feet long?
> 
> Stan, K5GO
> 
> Sent from my iPhone
> 
>> On Dec 19, 2022, at 2:57 AM, w5jmw at towerfarm.net wrote:
>> 
>> Hello all.I have a t antenna.50ft vertical and roughly 300 ft ntip to tip horizontal.I get a nice drop and resonance at abt 3.8 mhz.Is this weird resonant point normal??I would think it would be lower.I have another at abt 2.2 but almost a 3-1 swr..Normal ? I have used an inverted l before and resonant was abt right with a 1/4 wave length..thanks..john
> 
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