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Author Topic: Indoor antenna  (Read 2672 times)
W5WSS
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Posts: 1652




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« Reply #15 on: December 21, 2012, 06:31:49 AM »

Meant to say lowish feed point impedances for the rectanglular family of vertically oriented and vertically fed loops
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W5WSS
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Posts: 1652




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« Reply #16 on: December 21, 2012, 06:34:55 AM »

geeze meant to say high feedpoint impedances and lowish RR for the vertical family of rectangles
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WB6BYU
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Posts: 13027




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« Reply #17 on: December 21, 2012, 06:52:20 AM »

Quote from: W5WSS

...I suspect a lower impedance line eases the pressure on the tuner in this case...



Common T-network tuners tend to be more lossy at low impedances (below 10
ohms or so) and more efficient at higher ones, especially on the lower bands.

The 10m loop used on 20m will have a very high feedpoint impedance - if you
connect a feedline at that point it should be a high impedance type (twinlead,
etc.) rather than coax.  You might have to shift the wire lengths a bit if your
tuner has trouble matching it.

If you connect 50 ohm coax to a 1000 impedance load, a quarter wave later
it gets transformed down to 2.5 ohms.  The same length of 300 ohm line gives
you about 100 ohms instead, and is much easier for the tuner to match.
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W5WSS
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Posts: 1652




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« Reply #18 on: December 21, 2012, 07:51:07 AM »

OK I do not really have to use any line because I can place the tuner/s right at the feed point..I also have a Lmatch I will experiment with both ..So I have options between the various  combinations. 

And just measured for exact floor to ceiling dimension it is 10ft so 10+10=20 and 14 +14-28 48ft is the available space so I can either fill the space  or make the exact 10m version.

I could go with the 1 wavelength 10m version there is ample room or go with the 48ft wire and shape and feed.

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