Slinky antenna testing

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k9rzz

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I suddenly got the bug to try some slinky antennas, Don't know why. Guess 'cuzz I never had one before.

I put up one inside the room here. Worked okay. Bought another and connected it to the original, ran that down the hall ... worked better. Hmmmm.

Off to the store and bought TWO more!

So now I've got 260 ft of steel wire on a rope that's about 75 ft long.



Then I moved it to a higher spot and pointed it at Europe.



The results are interesting. When compared to a 100 ft random wire that's a little bit higher than this, the random wire beat the slinky every time by 10 to 20 db *except* in the 5 to 6 mhz range on signals coming from the direction the slinky was pointed. Then the slinky out performed the wire every time!

For example when listening to the aero stations such as Santa Maria on 5598khz or Gander 5616khz or RAF Volmet on 5450khz, the slinky gave louder signals consistently and with less noise. The airplanes were much clearer, instead of being half buried in noise, they were loud and clear.

FWIW, I've got it fed through a 9:1 transformer and some 50 ohm coax. I may try it without the transformer next.

Why it performs in only such a narrow freq. range I don't know. More testing needed!

Just thought I'd share.
 
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prcguy

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Not counting the slinky could be resonant somewhere that's beneficial, it looks like its very close to the ground which greatly lowers its efficiency. For most wire antennas on HF at the same height the signal to noise ratio will be similar. When you lower the antenna the signal and noise go down together and you can get to a point where the noise pickup is minimal its very pleasant to listen if the signals are still strong enough.

With a very low antenna you are also limiting the total amount of RF the receiver is seeing and reducing the effects of Intermod generated in the receiver and that can also lower your noise floor.

If you have the room for lots antennas and time to experiment, put up several at different heights and directions and choose the best one for the band you are using.
prcguy
 
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DaveNF2G

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What do you mean by "pointed toward" a direction? Do you mean the end of the slinky, or the sides?

A dipole is "pointed toward" an area when it is broadside to the intended receiving location. A long wire fires off the far end.
 

k9rzz

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Milwaukee, WI
From the feed to the far end it was pointed to the northeast, or Europe. The antenna was about 8 or 9 feet above ground, about the same as your typical beverage antenna. I did a little reading on what other's have done and it's kind of a 'wave delayed' antenna similar to the beverage. I'll post more when I get it going again. Fun stuff.
 
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