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Technical Topics => Equipment => Topic started by: Edgar Souse on April 27, 2017, 1321 UTC

Title: Limited space antennas
Post by: Edgar Souse on April 27, 2017, 1321 UTC
I am curious with those of you who live in apartments or HOA restricted communities do for antennas. I am currently in such a position and while I do not have a station setup yet I am looking into my options for equipment. I was considering a magnetic loop antenna, or getting a multi band dipole in the attic. Since my station would be used for transmitting in the ham bands I would like something that could do double duty. Although I am not opposed to having a separate antenna just for listening.

I also have an old VLF receiver at a relatives house I am hoping to get my hands back on soon. Are there any decent antenna options other than a random length of wire?
Title: Re: Limited space antennas
Post by: MDK2 on April 27, 2017, 1427 UTC
There's this one to consider:

http://www.kr1st.com/magloop.htm

I'm not a ham, but I've built two loops based on his SWL design (a different antenna from this, but it's linked from this page) and have had good results. The parts are cheap, easy to find, and easy to construct.
Title: Re: Limited space antennas
Post by: Strange Beacons on April 27, 2017, 1449 UTC
I am curious with those of you who live in apartments or HOA restricted communities do for antennas.

I am in this exact situation, i.e., living in an HOA-restricted condo community where putting an antenna outside is absolutely banned.  I researched the antenna subject for a few months, talked with many other hams, both in person and online, and finally reached the conclusion that a magnetic loop antenna was the best compromise that I could make in my situation. And because I am also in the situation where I have virtually zero space for working on any kind of a build project, I decided that I would just go ahead and buy a ready-made magnetic loop antenna. Here is the one that I purchased: http://alphaantenna.com/index.php?main_page=product_info&cPath=4&products_id=11

I also purchased the optional booster cable for 40 to 80 meters. This antenna is easy to set up, easy to tune, and I have had some remarkable QSOs with it, with the antenna sitting right next to my desk, inside of my condo.

I also run a 10m beacon out of my condo using an MFJ-1622 apartment antenna, which is another option you might want to consider. The MFJ-1622 does not work as well as the Alpha Loop in my situation, but you may get different results.

Curt / W9SPY
Title: Re:
Post by: Edgar Souse on April 27, 2017, 1535 UTC
Those loops look interesting. I suppose the compromise is a narrow band with and they likely aren't as efficient foe transmitting.  Back in a previous life I had a Kenwood TS140S (Great little radio, I now regret selling it) and a multiband vertical mounted in my parents back yard. Worked really well. As far as transmitting, I am concerned about RF exposure. I have yet to do any calculations, but am hoping that with an antenna in the attic, 100 watts will be a possibility.
Title: Re: Limited space antennas
Post by: Josh on April 27, 2017, 1802 UTC
I used a few turns of insulated wire around the window frame, fed by the tuner in a ic703 to make ssb contacts on 40m. Feed it at a corner and it's vertical, feed it in the middle of the bottom and it's horizontal. worked great for ambc and swbc use too, with a preselector. The drapes and blinds hid the entire setup. Not the best or most efficient of antennas but it worked.
Title: Re: Limited space antennas
Post by: moof on April 27, 2017, 2255 UTC
If you can get a magnet wire dipole up even 15 feet, I have worked most of the country back when the antenna was forbidden.  I have had people walking and sitting right under it and not notice.  It was weighted down with a bolt painted black attached with fishing line on each end about 6 feet up, kinda an inverted V.  Drilled a hole in the upstairs window and fed the coax barely outside.  Thick red mag wire can handle 100 watts.
Title: Re:
Post by: Strange Beacons on April 28, 2017, 1531 UTC
Those loops look interesting. I suppose the compromise is a narrow band with and they likely aren't as efficient foe transmitting.

I primarily use my Alpha Loop for transmitting CW and digital modes. I regularly get reports from the Reverse Beacon Network showing that my signal is being copied up to 2000 miles away. However, I have noticed that the Alpha Loop does not work as well for voice transmissions.
Title: Re: Limited space antennas
Post by: Unknown Name on April 29, 2017, 1606 UTC
If you live in an apartment you are screwed as far as HF is concerned.  The magnetic Loop would be my first choice.  You could try a High Sierra maybe.  If you live in restricted HOA community you can simply use a flag pole. ;)
Title: Re:
Post by: Edgar Souse on April 29, 2017, 1818 UTC
So, I'm currently I'm an apartment. My girlfriend and I are planning on moving in together. She has a house but the HOA expressly forbids antennas that "send or receive any ham radio signal" (my head exploded when I read that). I'm thinking some kind of loop, and a multiband dipole in the attic after I move. If I'm creative enough I might find a way of doing something outside. After the dust settles on the move I might consider asking for a variance as I suspect many of these rules are just a "copy and paste"
Title: Re:
Post by: Edgar Souse on April 29, 2017, 1821 UTC
Also, I hate HOAs as much as everyone else, but it will be the reality for now. I asked this same  question on another forum, and got a few useful replies and about 20 pages of irrelevant comments and people flaming each other.
Title: Re:
Post by: MDK2 on April 29, 2017, 1851 UTC
There was supposed to be a bill making its way through Congress that would allow hams antennas, regardless of HOA's or local zoning. I guess nothing came of that, but ARRL was pushing for it.
Title: Re:
Post by: Edgar Souse on April 29, 2017, 1912 UTC
From what I read, it died in Congress and was reintroduced this year. It was passed in the House so I guess it's waiting it's turn in the Senate. Given the worse than usual mess in Congress, I'm not holding my breath.
Title: Re: Limited space antennas
Post by: redhat on April 30, 2017, 0730 UTC
Note to self;

When house shopping, prioritize the following;

NO HOA,

3 phase power  8)

If you have no trees to hide a wire dipole in, your only option may be an antenna in the attic.  If your in an apartment and have access to the attic, you may be able to string a wire antenna inside.  I've done it in previous situations and it worked surprisingly well.  Just be sure the roof decking doesn't have foil coatings (like a radiant barrier) as it will act like a faraday cage and not let much in or out except noise.

Alternatively, you could try magnet wire out the window to a tree.  This is usually slender enough that no one will be able to see it and bitch...until they walk into it.

Good luck!

+-RH
Title: Re: Limited space antennas
Post by: Token on April 30, 2017, 1355 UTC
Also keep in mind that mag loops work well low to the ground.  So even in an HOA situation if you have a fenced back yard a one meter mag loop can often go outside and do quite well.  I know one individual who disguised a loop as art in his back patio area, so it, and its rotor, ended up in plain sight to everyone, but since it did not look like an antenna there was no issue.

T!
Title: Re:
Post by: Edgar Souse on April 30, 2017, 1452 UTC
I've been looking at some loop antennas. If they can be ground mounted, that would be a good solution. As long as it doesn't peak above the fence it would be fine

Don't think the roof has any metallic lining, but I'll check.

In my current apartment I have a balcony on the second floor and attic access.
Title: Re: Limited space antennas
Post by: redhat 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
Title: Re:
Post by: Edgar Souse 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
Title: Re: Limited space antennas
Post by: redhat 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
Title: Re:
Post by: Edgar Souse 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.
Title: Re: Limited space antennas
Post by: Unknown Name 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
Title: Re:
Post by: Token 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!
Title: Re:
Post by: Edgar Souse 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.