ad: M2Ant-1

2m antenna for attic? suggestions please

Discussion in 'General Technical Questions and Answers' started by KK5NL, May 26, 2008.

Thread Status:
Not open for further replies.
ad: L-HROutlet
ad: l-assoc
ad: l-rl
ad: l-Waters
ad: l-innov
ad: L-Geochron
ad: l-gcopper
ad: L-rfparts
  1. KK5NL

    KK5NL XML Subscriber QRZ Page

    I would like to add a 2m antenna to my icom 746pro, and I live in a restricted neighborhood.

    I use a Alpha Delta DX-EE HF 4-bander in the attic, and it works great. Now I would like to add 2m.

    I thought about using a small 5 element yagi (35" or so boom length), but I am concerned that I would need to then by a rotator, which isn't out of the question if there was a really good lightweight (no wind in my attic :) ) rotator for cheap.

    But aside from Yagi's, is there something that I could put up there fixed? Obviously I could use a simple vertical, any suggestions on ones that would work well with good gain?

  2. KD8BVS

    KD8BVS Ham Member QRZ Page

    I heard someone say that you can still put up (Ham) antenna's if you live in a neighborhood with antenna restrictions because Ham radio is used for emergency communications. I also heard that your neighborhood can't do anything about it because you are protected by the FCC or something. Has anyone else heard anything about this that can give me more information?
  3. WA8RTI

    WA8RTI Ham Member QRZ Page

    I think you are incorrect. PRB-1 requires local government zoning codes to give 'reasonable accommodation' to hams for antennas. However, it does not override private restrictions and covenants that people agree to when buying in a restricted development. Search the ARRL web site for PRB-1 and you can find the whole story. And to the origianl question-yes you should still be able to find a small rotor for a 3 el 2 meter beam that would be better than nothing.
    Last edited: May 26, 2008
  4. KI4TWB

    KI4TWB Ham Member QRZ Page

    I have a 2 meter vertical dipole in my attic that I use when the weather is bad and I don't want to chance the outside antenna. Works great!
  5. KA5LQJ

    KA5LQJ Ham Member QRZ Page

    What about a "Ground plane?"


    One of the simplest 2 meter antennas to build is the omni-directional ground plane. Now, you aren't going to hit repeaters over 60 miles away, due to the height above ground, but it should work repeaters within a 40 mile radius.

    Real simple to make. All you need is a chassis SO-239, some 4-40 bolts, lockwashers, nuts, some #12 solid, insulated, copper wire, some inuslated ring lugs, and string.

    Cut the radiator to 19 & 1/8" long, solder (or crimp) a small ring lug on the top, to accomadate the hanging string. Solder the "loose end" into the center pin of the SO-239.

    Cut the 4 radials to 20½" in length and put ring lugs on each end of the radiators so that the 4-40 hardware can go through. Bolt the radiator's on to each of the 4 holes on the SO-239. Bend the radials to a 45º angle. Put the string in the top and mount the antenna on the ridge beam. Hook up the coax, the best you can get and voilá.

    The above measurements should get you into the ball park, as far as VSWR goes.

    If you have the attic space, the Slim Jim, from works better.

    Respectfully submitted,

  6. KM5QF

    KM5QF Ham Member QRZ Page

    lean a J pole antenna amongst the rafters, easy to make. if you do need directionality check the arrl antenna book for plans on one called "the pounder".
  7. K0CMH

    K0CMH Ham Member QRZ Page

    I have had very good results with a j-pole in my garage attic.

    I built a copy of the Arrow Antenna dual band (2M & 79 cm). If you are not into building, the Arrow Antenna dual band J-Pole is very rugged and very reasonable (about $40.00 +/-).

    I have tried leaning the j-pole against rafters and it definately effected it (at least for me). I got much better performance when I tied some light poly rope to the top and hung it from the inside peak of the roof. My latest design is to make a mounting bracket that I nailed to the floor joist of the garage attic, and mounted the j-pole to that. It does not take any thing like heavy duty hardware in a protected space like an attic.

    Also, if you go the j-pole route, it is sensitive to metal objects on the same level and a little above it, but ignores anything below it. Stay as far away from metal vent pipes, wiring, etc. that is at the same level as the radiating element.

    Just google "j-pole" and you will find many, many directions. Visit the Arrow Antenna site. They also have very nice and light 2 meter or dual band beams. The cheapest roter you can find would work that just fine in an attic, provided there is sufficient room to rotate it.

    Good luck and hope you get things going.

    EDIT: Forgot to say that I have tried a number of center fed vertical dipoles, and the j-pole beats them significantly.
  8. KK5NL

    KK5NL XML Subscriber QRZ Page

    I have not used rotors before. Can someone tell me this.

    If I put a 5 element yagi up for 2m, would I reasonably be able to receive local repeaters within say 20-30 miles, without having to roate/tune it? And then be able to pull them in stronger by tuning?

    I ask because I would like to be able to scan my channels for local repeater traffic and not have to be looking at a map when I do it, but the added benefit of being able to focus in 2m ssb or 2m dx ssb even would be great..........

    Just not sure what to expect from a yagi not pointing directly at a local repeater, I have repeaters in all directions from me.

  9. KG6YTZ

    KG6YTZ Ham Member QRZ Page

    Just a quick question... How much vertical space are we talkin' about here? Your options will be limited somewhat by that. One could make do with, say, an MFJ-1724 on a slab of sheet metal if there is very little vertical clearance, but I'm assuming your attic space isn't quite that tight. :)
  10. WM5Q

    WM5Q Ham Member QRZ Page

    I'm confused. Are you looking to work CW/SSB or FM?

    CW and sideband are conventionally horizontally polarized, and being weak-signal modes typically you do need some gain, more being better of course, and gain means rotor. 3 elements isn't a lot, but it's better than nothing.

    FM, on the other hand, is strong-signal mode, and by convention is vertically polarized.

    A vertical is what you want for FM, but a beam is what you want for SSB. And anything DX is (usually) going to be SSB.
  11. KK5NL

    KK5NL XML Subscriber QRZ Page


    Correct me if I am wrong, but I figured even though its horizontally polarized, which generally represents roughly a 20db loss when working vertical polarized stations, that for local repeaters within 20-30 mi it would not be much of an issue.........but perhaps I am wrong, do people not use their horizontally polarized beams to work local 2m FM?

    I am wanting to do both 2m SSB as well as FM. I realize two antennas is the most ideal, and perhaps will go that route with an antenna switch.


  12. WM5Q

    WM5Q Ham Member QRZ Page

    It may not be a problem... I'm actually contemplating doing the same sort of thing at Field Day.

    3 elements gets you about +6 dB, maybe +8. I know I was estimating about 9-10 with 4 elements. Cross-polarization gets you -20 dB (or more, but we'll say -20). So with 6 dB of antenna gain, you're still 14 dB down, and that's a fair bit. ERP then, if you have 50 watts FM at the transmitter, is on the order of 2 watts.

    I figured it would work for me, but not by a whole lot .. it depends a lot on the local RF terrain and the repeater's coverage.
  13. W7LPN

    W7LPN Ham Member QRZ Page

    Last edited: May 27, 2008
  14. KK5NL

    KK5NL XML Subscriber QRZ Page

    I think someone is misquoting PRB-1. It is not referring to CC&R's but rather goverment permitting etc. You can just go putting a Yagi up 12ft over the roofline in a CC&R neighborhood. Its a contract, you signed it, and its binding, and the FCC's rules aren't really helping you much in that situation.
Thread Status:
Not open for further replies.

Share This Page

ad: SteppIR-1