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Author Topic: Limited space antennas  (Read 3182 times)

Offline redhat

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Re: Limited space antennas
« Reply #15 on: April 30, 2017, 2017 UTC »
Your mileage may vary, but I'll take an attic dipole over almost any mag loop.  I was able to squeeze a inverted V with slightly bent ends in the attic of my top floor apartment, but it had a rather high peaked roof.  It was noisy for receive, but had no trouble getting out.  I used plastic electric fence insulators with fender washers and drywall screws to the cross members of the roof, with a simple balun.

+-RH
Somewhere under the stars...
WinRadio Excalibur/305 w/ a chi-town resonant loop, Kenwood KDC-U356 for mobile listening.
Please send QSL's and reception reports to xfmshortwave [at] gmail [d0t] com

Offline Edgar Souse

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Re:
« Reply #16 on: April 30, 2017, 2247 UTC »
The attic and roof have no metallic shingles or coating, so a dipole would work. I'm wondering what the fire hazard would be with higher voltages on the ends of the dipole. I won't be running more than 100 watts.

I saw plans for a home made multi band trap dipole. Could be a good project.

The Mag loop antennas get great reviews but are pricey.

The MFJ 1622 seems a less expensive and quick way to get going, but not sure how good it is
RSP2 Pro, IC-7300, W6LVP Loop, 35' severely compromised dipole
Dallas, Texas, USA

Offline redhat

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Re: Limited space antennas
« Reply #17 on: April 30, 2017, 2324 UTC »
It boils down to how large your attic is, and what bands you want to work.  40 meters is about the practical limit for most large houses for an attic antenna, but you can play games with zig-zagging the wire around.  As long as there are insulators on the ends, at 100W I doubt you'll have trouble with arcing.  I would guess you'll have more trouble ridding the house and its contents of RFI.

+-RH
Somewhere under the stars...
WinRadio Excalibur/305 w/ a chi-town resonant loop, Kenwood KDC-U356 for mobile listening.
Please send QSL's and reception reports to xfmshortwave [at] gmail [d0t] com

Offline Edgar Souse

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« Reply #18 on: May 01, 2017, 0041 UTC »
You're probably right. I'd really love to work 80 and 160 but I don't see a way around it right now. I think the US is getting some MW bands below 160 meters that would be interesting, but unless one has a few acres in the country, I don't see it happening.
RSP2 Pro, IC-7300, W6LVP Loop, 35' severely compromised dipole
Dallas, Texas, USA

Unknown Name

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Re: Limited space antennas
« Reply #19 on: May 01, 2017, 1635 UTC »
Edgar, if you have attic access you should watch video below.  This antenna would also work on 160 and 80 if you make separate loading coils, simply wrap wire around PVC tubing.  Good Luck. 
https://www.youtube.com/watch?v=as5nVgicVxE

Offline Token

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Re:
« Reply #20 on: May 02, 2017, 1500 UTC »
I think the US is getting some MW bands below 160 meters that would be interesting, but unless one has a few acres in the country, I don't see it happening.

I assume you mean the new allocations (in the US) of the 630 and 2200 meter bands?  There are power and antenna restrictions on those bands, and the EIRP on 630 meters will be either 5 or 1 Watt (depending on your location) and 1 Watt on 2200 meters.  This means few will be attempting to build big, full size, efficient antennas, and most will use some kind of physically small loaded antenna for transmit and very likely some kind of loop for receive.  In other words, a regular city lot size piece of land may be perfectly adequate…although I would not like to try those bands in a city style QRM environment.

T!
T!
Mojave Desert, California USA

Offline Edgar Souse

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« Reply #21 on: May 02, 2017, 1517 UTC »
I wonder why the power limits are so low? If nothing else it could make for some interesting listening. I don't know of anything able to transmit that low that the average amateur operator could get their hands on, unless it involves modding commercial gear.
RSP2 Pro, IC-7300, W6LVP Loop, 35' severely compromised dipole
Dallas, Texas, USA