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Author Topic: Great Limited Space Antenna  (Read 864 times)

Offline mysticstar

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Great Limited Space Antenna
« on: October 28, 2018, 1725 UTC »
     Back in the early 90's I started listening to shortwave and collecting QSL cards from all over. It was a difficult time as I was still living in an apartment with my wife and I didn't have a lot of money to put into my hobby. Necessity is the mother of invention. I bought a Knight R-100 receiver used at Ham Radio Outlet for next to nothing. All I needed was a decent antenna, but where would I put it? At that time I was living in a third floor apartment with a balcony and didn't have the big money to try an active antenna. So I decided to build something that I thought made sense to me in my mind. Fortunately, I was working as an electrical apprentice back then and always kept my eye open for scrap "anything". I grabbed a 6-8' piece of 2-1/2" PVC pipe and went out and bought a 500' roll of #12 black solid wire. I started at the end of the pipe and drilled a couple holes to secure the end of the wire, set up the wire so it would pull off evenly and began to closely wind the wire onto the PVC making sure that the wire was close, tight and neat. When I got to the approximate middle, I drilled a couple more holes to secure it again, leaving a little extra and then cut. I then repeated the process on the other end ultimately ending up in the middle again. I made sure that whatever I had on one side was equaled on the other. Now it was time to attach whatever I was going to use as feed line, whether it be RG8, RG-58 or RG-8X. Basically what you have in the end is a close helically wound dipole that you can just sit on the balcony at night and take down when you are done. I wasn't prepared for the outrageous reception I got using this antenna. Granted, I was up three floors, but looking back, even after I moved from there, it continued to be a great antenna. Years later I was using it as a second antenna and sometimes it was the better signal.
     So if you are looking for a decent antenna that will fit almost anywhere, isn't affected by HOA's, and is easy on your pocket, try this out. It works better if you have an antenna tuner or even build one yourself. At the time, I was living in Newark, DE and I would get up at 2 in the morning sometimes to try and log some decent stations. One card I received was from Radio Luxembourg who was broadcasting with only 10kW of power and it was considered a domestic station. So don't get discouraged. You don't need the best rig and best antenna system to make good contacts. You just need determination, patience, creativity and perseverance.
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Offline Josh

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Re: Great Limited Space Antenna
« Reply #1 on: October 28, 2018, 1744 UTC »
Neat! I had a similar pvc loopstick antenna back in the day, had it sitting atop the curtain rod. Its design came from some swl or electronics magazine, the cliff dwellers antenna or somesuch. Not wound as a simple inductor but used three wire rotator cable.

I had a balun fed sloper going from the 2nd story bedroom window to the mailbox at around 100ft and it did fine as a all around vl/m/hf antenna but was more or less vertically polarised, wanted an horizontal antenna to do some comparasons with, the cliff dweller was a decent compact horizontal.

If a sig was fading on one ant, switching to the other almost always made a difference, used to monitor with regularity a bfsk baudot news bcast from Rabat Morocco around 19Mhz when Icom R-71As and Infotec M600s ruled the earth and one would open and close the band while the other was decidedly superior during the stable reception period. Back then you had fax, baudot, and vft everywhere instead of S4285, good times. Not that S4285 is bad or anything.
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Offline ChrisSmolinski

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Re: Great Limited Space Antenna
« Reply #2 on: October 28, 2018, 1842 UTC »
I lived in an apartment for a year, and had a similar antenna, a bunch of turns wrapped around a PVC pipe, hung above a window where a curtain rod would go. Nothing spectacular, but from memory it (sort of) worked.  This was with my Icom R-71A also  ;D
Chris Smolinski
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Offline Josh

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Re: Great Limited Space Antenna
« Reply #3 on: October 28, 2018, 2052 UTC »
Lol see that's what I was thinking too when I read the piece on building the antenna, that it'd be about as good as a similar length of wire as the pvc pipe, 6ft or so of wire. Switching between the two showed that it indeed was a worthy companion to the 100ft sloper. However, I think the R71 was doing the heavy lifting.
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Offline ChrisSmolinski

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Re: Great Limited Space Antenna
« Reply #4 on: October 29, 2018, 1016 UTC »
It was a challenging listening environment, between all the RFI generators and the fact that the local MW station was right behind the complex. At least it was only a 1 kW station.

Agreed that the R71A was the major factor in being able to hear anything. It certainly wasn't the antenna  ;D
Chris Smolinski
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Offline Pigmeat

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Re: Great Limited Space Antenna
« Reply #5 on: October 29, 2018, 1617 UTC »
I've found that two , two ft. 1 inch i.d. lengths of 18 gauge wound tight together work as well as a 60 ft. longwire out the window. One section goes vertical the other horizontal. That set up would grab listenable audio a half hour before my other antennas would in the static season, it was very quiet once you toyed with it.

From mid-May to early October it ate my other antennas up.

Offline mysticstar

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Re: Great Limited Space Antenna
« Reply #6 on: October 29, 2018, 1705 UTC »
   Oh man! That must have been something. That MW station behind me would have driven me crazy. It just goes to show though, that we'll do anything to get a better signal while staying in the guidelines that are established, like apartment rules, or HOA's or even money. We'll come up with a design and then constantly experiment to try and improve what we built to get acceptable reception! :) Once you're bitten by the radio bug you're toast. That's why I like forums like these because it's a wealth of information for people like ourselves who are looking to trade ideas and information regarding the hobby. (and to make our stations better.) :)
    Pigmeat, that sounds really interesting. Can you give me some more details on that antenna? Do you still use it?
« Last Edit: October 29, 2018, 1918 UTC by mysticstar »
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Offline Pigmeat

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Re: Great Limited Space Antenna
« Reply #7 on: October 30, 2018, 0843 UTC »
It started out as a Radio Nederlands design for a MW loop. I got bored with MW, but I still had the PVC and wire laying around. I was looking through a copy of "'73"  magazine at the news stand, they had a larger version of the PVC upright "L" for roof-top dx'ers.

I had roughly 120 ft. of 20 gauge speaker wire left from the loop. I cut the pipe down to fit inside the window and left a short rat tail of bare wire on the end to have something to attach a stripped length of coax w/ alligator clips to the business end of the wire wrapped PVC sections. The other end of the coax fed a small hamfest tuner and there was another 18 inches of coax feeding the tuner to the receiver.

I didn't expect it to do a thing, but I was very pleasantly surprised with it. That "fade altering" thing  Josh mentioned when you switched clips was a real "WTH?"moment.

I built that thing when SW was roaring. The African and S. American stations on 60 meters came in a good half hour earlier with it than the rest of my wires.

Offline Josh

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Re: Great Limited Space Antenna
« Reply #8 on: October 30, 2018, 1944 UTC »
The problem is any time the signal hits the ionosphere or earth it changes polarity to something other than vertical or horizontal. And it can rotate too. It's nice to have antennas that respond best to a variety of polarisations. And of course there's the multipath, each fraction of wich will have different polarity as well as differing times of arrival. If you decode fsk and have a scope for tuning, you can see the multipath as distinct eye patterns larger or smaller than the primary eye pattern. I'll try to get a screen cap showing a good deal of multipath, the 12577 gmdss freq is really good for it. Multipath doesn't really effect voice operations much, but it's hell on digital modes.
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Offline mysticstar

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Re: Great Limited Space Antenna
« Reply #9 on: October 31, 2018, 0018 UTC »
So guys, I'm takin' it that this was back in the early 90's when SW was wailin'? The reason I ask that is that is when I was getting all kinds of cards because there were so many stations on. Right now, I am assuming that we are at the bottom of the solar cycle? And it's not unusual right now to see entire bands closed, is that right? I was listening to a station last night that was fading in and out pretty clearly, then it faded out and never came back. I was like, "No way!" But yeah, you're right. They arrive at different times and it really screws with me sometimes. I know what you are talking about Josh in regard to decoding FSK. I would really like to see that screen capture.
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Offline ChrisSmolinski

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Re: Great Limited Space Antenna
« Reply #10 on: October 31, 2018, 1238 UTC »
The higher bands are indeed open less often at the bottom of the solar cycle. However, the lower bands are doing great. Personally, I prefer solar minimum vs maximum, we don't have the continuous solar flares that wreck reception for days at a time. Plus we're entering winter in the northern hemisphere, it should be an excellent one for MW and longwave DX, as well as the lower part of HF.
Chris Smolinski
Westminster, MD
eQSLs appreciated! csmolinski@blackcatsystems.com
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Offline Josh

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Re: Great Limited Space Antenna
« Reply #11 on: October 31, 2018, 1701 UTC »
Also less qrn due to reduced tstorm activity in the northern hemisphere in winter. But yes, not only is the solar cycle at or near minima, there's less to listen to that isn't military or commercial digital. You can always dx the mil and commercials as some radiate from far off locations, but they might not qsl.
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Offline Josh

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Re: Great Limited Space Antenna
« Reply #12 on: October 31, 2018, 1845 UTC »
This screencap shows some multipath in the tuning eye pattern on the scope;
https://www.filemail.com/d/blxgylfoarsrnot
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Offline mysticstar

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Re: Great Limited Space Antenna
« Reply #13 on: October 31, 2018, 2355 UTC »
Thanks for sending me that. I had no idea there were so many. I wish I had an antenna that was able to deal with all the different ways that the signal arrives. I just never really thought about all the different patterns.
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Offline Josh

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Re: Great Limited Space Antenna
« Reply #14 on: November 01, 2018, 1835 UTC »
The good thing is just about any conductor will serve as an hf antenna, no matter the polarity of the signal.... to a degree.
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