Eves Mounted Wire Antenna

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by K2POP, Aug 7, 2011.

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  1. K2POP

    K2POP Ham Member QRZ Page

    Our new home has a HOA and antenna restrictions. :( The “best” place I can put a wire antenna (from a “stealth” point of view) is on, or under, the roof eves. (The back yard is small.) Unfortunately, that is not the best place from an efficiency point of view. While I am looking for better alternatives, I still want to build an eves mounted antenna to see how it works. Do you have any suggestions or know of any plans?

    The roof perimeter is about 170’, in a 40’ x 45’ rectangle. The eves are about 20’ above ground level, the roof is tile, and the fascia boards are wood. The antenna can be fed with coax or ladder line, I have a wide matching range tuner, and the feed point can be in the middle of the back leg (40’ side) or at one corner. With the tuner, I want multi-band capability.

    I could put-up a full size 80m dipole and wrap the ends around the sides of the house. I could do the same with an OCF dipole, folded dipole, zepp, “cobra” antenna, etc. I could build a “tripole” and wrap it around the sides of the house with the third leg going vertically down from the feed point almost to the ground. (I don’t have any details on this one.) Alternatively, I could build a random length antenna or an open or closed horizontal loop antenna. I could even wrap the wire around the house several times and get a really long wire or multiple wire loop antenna.

    Obviously, putting an antenna against the house eves and only 20’ agl is not optimal. However, if you can transmit with a light bulb, then I should be able to transmit and receive with this. The questions are:

    What antenna design(s) do you think have the best chance of working out? Do you know of any plans I can get for an eves mounted antenna?

    Thanks, Richard
     
  2. N0BOX

    N0BOX Ham Member QRZ Page

    People will, no doubt, suggest using a ladder line feed, which will allow you to get better multi-band performance out of a wire antenna and an external antenna tuner. My vote would be to lean towards a center-fed style antenna, though, since it will reduce your chances of running into "RF ground" issues that can cause you to end up with RF in the shack. Using end-fed or OCF antennas don't necessarily mean that you will have any issues, but it's easier to just use a center-fed antenna style if you don't have a need for the other styles.

    Other than that, just use whatever antenna style will allow you to get the feedpoint to the highest point available. You can use the ladder-line feed to lower losses when you are having to use a tuner, but you could also consider a fan dipole to give you a better match on a wider number of bands. Separate lines for 10, 20, 40, and 80 will give you the ability to also get very close to 15 and 30 (since 40 and 15 are harmonics as are 30 and 80). You would also be within a tunable range of 12 and 17, even if you couldn't use your rig's built-in tuner to match them.

    You should get a decent signal out on everything 20m and higher if you are up at 20+ feet at the feed point. Everything lower than 20m will have "less than optimum" performance, but if you're getting a signal out there when you're "NOT ALLOWED TO" because of some anal-retentive HOA nazis, then you are doing a lot better than you're supposed to be.
     
  3. K2POP

    K2POP Ham Member QRZ Page

    Thank you. I thought about a fan dipole, but usually each of the shorter lines need to be separated from the longest line and from each other. For an eves mount, I could have multiple lines but could only separate them by an inch or two. Do you think that would work?

    If I mount any type of wire antenna on the eves, do you think it would work better if I used short stand-off insulators (1-1½ inches) rather than mounting it directly on the fascia boards?
     
  4. K7JBQ

    K7JBQ Moderator Volunteer Moderator QRZ Page

    The fan dipole would be a PITA to tune, but with patience you could make it work.

    I used an "eaves antenna" when I lived in a townhouse in Maryland, and it worked pretty well. I had the end insulators tied to ropes that I would pull out and secure in the ground with tent pegs when I was operating, then roll up and stash in the bushes until the next session.

    I did stand it off the eaves by about an inch, but I doubt that made a huge difference. It just seemed like a good idea at the time.

    73,
    Bill


     
  5. KA9VQF

    KA9VQF Ham Member QRZ Page

    I built just such an eves mount antenna a few years back and though it was not exactly a pileup buster it did work fairly well on all the HF bands but 160, with my little manual MFJ tuner, until I was able to put up the semi resonant hunk of wire in the sky I use now.

    I used empty wooden thread spools with #16 cement coated nails through them to hang the wire from.

    I ran my dipole legs from the back of the house under the eves and drain troughs on the back side of the house, to the outside of the fascia, then up to the peaks of the roof and down again, and back under the eves and drain tough on the front of the house, then fed it with RG-58 coax out on the front of the house near my operating station, because that is what I had handy when I put it up.

    I used steel electric fence wire because I still had a half mile or so of the wire on a spool left over from when I was a weekend farmer.

    I’m still using the end that was on the east side of the house as a BC antenna with a SX-71 in my kitchen. I have reconfigured the end I’m still using into a delta loop and it works nicely for that.

    I know its real hard to find wooden thread spools but if your handy with wood working machines at all {and have any on hand} you should be able to make something suitable.
     
  6. K9ZMD

    K9ZMD Subscriber QRZ Page

    I used an under-the-eaves doublet for a few months while renting a small 2-story house in a garden community. It was cut for 40 meters from #14 stranded with black insulation, and the transmission line was 300 ohm TV twin lead. No technical rationale for those choices, that's the stuff I had on hand. Some black electric fence insulators held the wire about an inch off the inside of the facia boards on three sides of the house. I centered the antenna on the gable end of the house, then used a nearby upstairs window as an entry point. I just threaded the twin lead past a slight bow in the screen frame, then formed it into a U shape and pressed the vinyl window shut on it. A transmatch in the shack easily tuned the system on 40 - 10 meters.

    The antenna worked well enough for transmitting, but reception was quite a disappointment. Low signal strength and high noise level combined to make all contacts hard-fought. In spite of that, I did make quite a number of contacts in all US call districts as well as a few DX entities (AK, HI, Japan, and Canada). The noise was probably from domestic appliances in my own home, as well as in the many closely spaced houses of that tiny community. Had we lived there longer, I would have attempted using an MFJ 1026 noise cancelling signal enhancer. More fiddle-factor, but I'm guessing it would have greatly improved my operating enjoyment.

    As it was, few of my contacts resulted from CQing. I could hear replies, but most were not copyable. Consequently, I resorted to search and pounce operation. Truly, if I could hear them, I could work them, although I knew there were a lot more signals I could have heard much better with an antenna high and in the clear.
     
  7. N0AZZ

    N0AZZ Ham Member QRZ Page

    I would think configured as a loop would give good performance on 10-40m an NVIS but with some DX possibilities as well. I have used several loops in the past and have been pleased with them for multi-band use.
     
  8. AJ4CM

    AJ4CM Ham Member QRZ Page

    I have a homebrewed 1/2-size G5RV under my eaves that I've used for a few years. It works okay, but not great. With PSK I've used it to work a fair amount of DX, but the performance isn't good enough for much DX success on SSB. I used plastic electric fence standoffs to hold it a couple of inches away from the facia boards.

    Last weekend I strung a homebrewed 75m dipole through the trees, fed with window line, and it's far far superior to the old antenna. How much difference is due to the antenna type and how much is due to not being under the eaves I can't say.

    I do think window line, with its low losses, is the way to go if you're in a compromised antenna situation. You've already got enough working against you without throwing away watts in a coax. If I were you, I think I'd throw up the longest doublet I could make fit without worrying about resonance, feed it with window line, and use a tuner to match it your radio.

    Plan on using efficient modes like CW or PSK a lot of the time to make up for installation shortcomings.
     
  9. AA4VX

    AA4VX Ham Member QRZ Page

    I would go to http://www.sgcworld.com/ and download any number of there documents. You sound like Base Quadra Loop Horizontal example in the 230 SGC tuner manual modified for your location would do the trick. As for their line of tuners all I can say I had mine for years and the 230 will load bedsprings. Note I'm not claiming it a good antenna just that I made a contact doing it. I’m running mine now as a Base ladder installation and I have worked DX with it. This way the tuner can be hid in the attic and depending where your shack is I personally would run very High Grade coax like Bury-Flex RG 8, Times LMR 400 as you don’t want to lose watts or receiving db’s in the coaxial run.:) Run the coax close to the roof and drop the coax down an inside wall. Try and keep it away from your electrical lines. 73 Gene K2QWD
     
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