Antenna Recommendation Please

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N7SUN, Nov 13, 2015.

ad: L-HROutlet
ad: l-rl
ad: Left-3
ad: Left-2
ad: L-MFJ
ad: abrind-2
ad: Subscribe
  1. N7SUN

    N7SUN Ham Member QRZ Page

    I'm currently using a Cobra Lite folded dipole antenna in an inverted "V" configuration. There are no tall trees at my QTH, so the feed is attached to a short steel mast attached to the chimney and the ends are about five feet off the ground. Performance is OK, but I'd like to do better. BTW - my house on a beach and the antenna location would be about 200 feet from the salt water and about ten to fifteen feet above the mean tide line. I don't have a HOA to deal with, but do have an XYL who is very particular about aesthetics and visual impacts. I'd love the install a multi-band hexbeam, but the size (20' diameter) will not pass muster. I've considered verticals (Steppir, Zerofive, DX Engineering, Gap Titan DX), but from what I've read, they probably won't perform appreciably better than what I'm using now.

    All antennas are compromises of sorts, I'm looking for something that will work better than what I have now for 10 - 40 meters (80 would be good too) that the XYL can live with.

    Any suggestions?

    73,

    N7SUN
     
  2. KD6RF

    KD6RF Ham Member QRZ Page

    Not sure why you came to the conclusion that the verticals wouldn't perform better.

    The Cobra isn't exactly the pinnacle of efficiency, and can actually be quite lossy depending upon the construction materials and methods. And, being that low means a large penalty for low angle DX worthy radiation on the low bands.

    That's where a vertical shines (with a good radial system) - low angle radiation down on the lower bands where your low mounted Cobra is shooting the energy straight up and at high angles.

    And the closer you get to salt water the better!

    Perhaps you can trade off the aesthetics and visual impact of a nice vertical antenna at the water's edge for the aesthetics and visual impact of a nice diamond ring :)

    .
     
  3. W1VT

    W1VT Ham Member QRZ Page

    A temporary wire vertical for 15 or 20 meters hanging off an fiberglass pole with two elevated radials may enable you to decide whether or not verticals are enough of an improvement for your situation. While one might expect better DX performance, not everyone is into working DX.

    My QRZ web page shows a 20' Flagpole vertical that covers 40 through 10 meters with an autotuner mounted at the feedpoint. With a tuner in the shack it does OK on 20 and 30 meters--I called CQ on 30M JT65 recently and a VK3 came back.

    Zack W1VT
     
    Last edited: Nov 13, 2015
  4. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    If you own the property right down to the water line, a vertical very close to the water (not 200' away) might work extremely well. Of course, too close and it can be underwater during tidal surges.

    I'd shoot for finding the highest tide line if possible and installing a vertical just about there, with radials running on land (under the sand, or between rocks, or whatever there is) and let the ocean help.

    A vertical installed at saltwater is substantially better than the same vertical installed inland. Of course, the salt spray is hard on aluminum; the SteppIR "BigIR" vertical is fibreglas with a beryllium-copper radiator inside and all stainless steel hardware and might fare better near the ocean.
     
    W8ZNX likes this.
  5. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    Is the ladder line of the Cobra well away from any metal like the support pole you mentioned.? That could be an issue. Any possibility of getting the apex up substantially higher, say with a fiberglass pole? That might be a relatively easy improvement.

    A vertical would do very well in your location as long as the ground losses are made low. Is the ground at your property saturated soil or is it solid rock? If it is saturated soil that helps and you may not need as many radials. Otherwise be prepared to put down at least 20 radials unless you can use elevated ones, or can put the vertical on the beach as suggested above.
     
  6. N7SUN

    N7SUN Ham Member QRZ Page

    Great point, the ladder line is actually zip-tied to the conduit - Yikes! I'm going to pull it away and see if that helps,,,,,,

    Thanks!
     
  7. N0TZU

    N0TZU Platinum Subscriber Platinum Subscriber QRZ Page

    Yes, give that a try. I would stand it off from the mast 5 times the distance between the line conductors or more. Look at plastic stand offs made for electric fence which are inexpensive as one option. Also, extra ladder line needs to be cut off, not left in the circuit loosely coiled up like coax can be.

    Good luck and let us know how it goes.
     
  8. W8ZNX

    W8ZNX Ham Member QRZ Page

    Ahoy

    keep the wire antenna for close in work
    get a vertical put it as close to the water
    as you can
    put a good ground system under it
    you will get out like gang busters

    and yes you do not want open wire / ladder line
    feed next to a metal support

    mac
     
  9. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    It surely will help.

    Can't do that.
     
  10. KC9ZHR

    KC9ZHR Ham Member QRZ Page

    at low height a vertical is usually better......as far as appearances go spray paint is cheap. I spray paint all my antennas and masts to mach surrounding structures and it blends in very well.

    as far as the cobra goes the idea behind it is to use linear loading for the whole length so you can get lower bands in a tighter space(with some loss too). If your only after 40m and up I say get rid of the 3 wire legs of the cobra and replace each side with 33 feet of wire (40m doublet) and then you dont have the loss anymore and can cover 40m and up :)
     

Share This Page

ad: QSKLLC-1