Need help deciding on an HF antenna

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by K3TOM, May 23, 2019.

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  1. W2WDX

    W2WDX Subscriber QRZ Page

    If you can, I do highly recommend either a fan dipole for your preferred bands fed with quality coaxial with a good choke balun at the feedpoint or a true doublet fed with balanced line and a good quality wide-range external tuner. The latter being the preferred choice since it will exhibit the lowest losses and best multi-band performance.

    Height is the key issue for horizontal wires. Mostly at the feedpoint. Inverted-V tends to be more omni-directional than a flattop dipole when they are both high enough, which could be preferred. Conversely, if high enough, some gain in two opposing directions can be expected from a flattop dipole on the band it's cut for. A more complicated pattern for any others. Inverted-V can be easier to install, since the big height is needed only at the center feedpoint and you are less concerned with directional orientation. I screwed a large eye-bolt in the main truck of my maple tree in my front yard for one end of the inverted-V, at just the height of of a big extension ladder. Which is fine and should have little or no impact on the health of the tree.

    Currently I am using an inverted-V fan dipole with elements trimmed for 75m and 40M with a good choke balun and LMR-400 coaxial. It's 117' long at the longest length. Works great and can tune easily on a few other bands (with some losses). I am currently making my 600 ohm balanced feedline to covert it over to an 75M doublet for multiband use. I have a mast extending up from the roof to about 60' at the feedpoint which works well for most bands.

    I do recommend you build it well ... mechanically. Nothing sucks more than having to regularly go out and rehang an antenna because you "cheaped-out" on design or materials. I live on Long Island, NY and we get some serious wind and snow events here, salt air, and we recently had a pretty bad wind event here. My antenna is fine because I spent a little more on good quality parts and steel copper-weld heavy wire. The wire I chose and the hardware & tie-off rope I used to construct it (in a mock up) was able to support my weight plus pulling on it while hanging from a tree vertically (that was my "break test"). It didn't stretch any after the test. I can't tell you how poorly an antenna functions when it's broken laying on the ground! :D Basically, always consider gravity and the total weight of the entire antenna, then factor in wind and design accordingly. Doing so will help ensure the antenna lasts many years, assuming the support structures remain. So also chose them smartly.

    As far as trees are concerned, treat them like the living organisms they are. Remember to not do anything to damage bark or limbs since this can lead to the tree getting sick and die. It is better to screw into a tree with a stainless steel threaded eyebolt than simply tie a rope around a limb or trunk. The tree will naturally grow around the eyebolt, where the rope will cut and damage the bark due to movement, making the tree susceptible to rot or parasitic infestation. However, this can be problematic from a practical perspective since the heights involved can be daunting. Just be aware of this. Many an antenna have come down due to the limb or entire tree being weakened by this kind of damage to a living thing.

    Now as for a vertical, if you have the physical space to lay out a good radial system, is also good for long-haul DX if conditions favor that polarization. Again, bigger is better. So having both, hopefully a good distance from each other, is a nice thing to have since conditions do vary.
     
    Last edited: May 24, 2019
    NH7RO likes this.
  2. W8LLW

    W8LLW Platinum Subscriber Platinum Subscriber QRZ Page

    My experience in the hobby is just 3 months. No Uncles. The first two HF antennas that went up are wire. The one for 20 meters is a horizontal dipole strung between two trees at 30 feet. The 40 meter wire antenna is a vertical. It has one vertical and two horizontal radials at eight feet from the ground, that is where the feed point is. Both wire antennas have a 1:1 air core balun of the home brew type. These were accomplished by watching videos and reading many threads.

    With these two wire antennas I have made contact to about 50 countries including Uganda, Australia and St. Helena Island. Qth is Michigan. In your price range, you can get the same antennas plus an analyzer. The analyzer allowed these antennas to get tuned to below 1.5:1 across the general phone frequencies. Get yourself an analyzer if you cannot borrow one. With a well tuned antenna and good coax you can rock the band even in the poor conditions. If this is what everyone is calling lousy, I can't wait to see what happens a couple years from now.

    Best of luck with your upcoming antenna farm.
     
    WN1MB and NH7RO like this.
  3. NH7RO

    NH7RO Ham Member QRZ Page

    I second the analyser advice; while not necessary---they are so useful and fun to use that I can no longer imagine not having one in my shack.

    The RigExperts are top-notch and worth the money in my (and many other's) opinion.

    73,

    Jeff
     
  4. WB5YUZ

    WB5YUZ Ham Member QRZ Page

    So far this month I have been on the air on eleven different days. I have thirty-two contacts, twenty-three of which were DX. All were on 20 or 40m with low vertical loops (the 40m one is fed for vertical polarization and models out to look a lot like a conventional vertical, but with a less pronounced overhead null) and one hundred watts CW.
     
    K0UO and NH7RO like this.

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