[TowerTalk] Linear loaded KE4UYP vertical
robrk at nidhog.net
Thu Jul 24 23:57:13 EDT 2008
I got confused with a vertical antenna and "Totally Omnidirectional
pattern of high wave angle horzontally polarized Radiation"
> Don't believe everything you read in print. I just modeled an 80 meter
> version of that antenna, using the recommended dimensions, top wire at
> 31 ft and 65 ft long, with 82 ft of wire in the vertical portion with
> the bottom wire 5 ft above ground.
> It resonated at 3.69 MHz with an impedance of 26 ohms. He claims the
> longer wire on the vertical side off-center feeds the antenna and raises
> the impedance to 50 ohms. Didn't work for me. If you matched the
> antenna to 25 ohms the 2 to 1 SWR bandwidth would be about 70 KHz. (He
> claims 300 KHz). The gain is 2.9 dBi straight up. (He claims 1 dBi.)
> 2.9 dBi is about the same as an 80 meter dipole at 18.5 feet. He claims
> it is 80 to 85% efficient. EZNEC calculates 4.13 dB loss. That's
> equivalent to 38.6% efficiency. He claims it is totally
> omni-directional. At 30 degrees elevation it has a F/B of 3.6 dB.
> I didn't include the feedline or any metal support poles in the model.
> I didn't do the 160 meter version, but I would expect much poorer numbers.
> Jerry, K4SAV
> Marinus Loewensteijn wrote:
>> Long time lurker here but I have a question that I do not seem to be able to answer satisfactory.
>> At the moment I have 44 foot doublet up for 80 and 40 and am wanting to move away from a balanced feeder to coax. I am thinking of putting a scaled version of the above antenna up for 40 first before 80m.
>> If it is totally a disaster then I may put up a rotatable dipole lke the Cushcraft D40 or Hy-gain Discoverer 7-1.
>> Due to size restrictions and to the location of TV satelite dishes of both myself and close neighbours I cannot put up anything larger than this.
>> I wonder if any of the TowerTalkatonians has opinions or experience with this antenna. ( members.tripod.com/~KE4UYP/80m_160m_Antenna.html)
>> Many thanks in advance, 73 Marinus ZL2ML ..
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