Wire beam vs aluminum beam antenna

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by AE7F, Nov 2, 2015.

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  1. AE7F

    AE7F Ham Member QRZ Page

    For anyone considering the choice between a wire beam (such as a hex beam, spiderbeam, optibeam, etc.) or a traditional aluminum beam, it might be useful to have a list of the pros and cons of each. I have now used both the spiderbeam and hex beam antennas in addition a couple of aluminum yagi antennas as well and this information comes from trial and error with these antennas. If anyone has any additional items to add, feel free to do so. Maybe this can help someone in their decisions:

    Wire Beam Pros:
    • Light weight
    • Low wind load
    • Possible to utilize light or medium duty masts, towers, or rotators instead of more expensive heavy duty counterparts
    • Possibly easier to use NN4ZZ Hex Lock or similar hinges due to less antenna weight on the hinge
    • Flexible in wind
    • Many types of wires, ropes, clamps, and supports to choose from
    • Non conductive support arms/booms
    • Possibly less expensive and easily obtainable construction materials
    • May be easy to use for experimenting or proving concepts
    • May be easy to use for portable operations
    • Can be excellent choices for towers or masts which can telescope, retract, or tilt
    • It has been mentioned that insulated wire is quieter during RX
    Wire Beam Cons:
    • Successful antenna function seems to be more dependent on weather
    • Depending on specific weather at your QTH:
      • UV deterioration of fiberglass, rope, wire
      • Possible destruction of antenna due to heavy snow and ice loading
      • Periodic or constant guy rope, wire, or fiberglass adjustments, re-tensioning, etc.
      • Possible requirement of a tilting or telescoping tower or collapsible mast for more frequent maintenance
      • Possible requirement of tower climbing and safety gear when going up the tower for more frequent maintenance
      • Possible necessity of hiring boom truck more frequently if antenna is inaccessible
    • Possibly more expensive than thought if maintenance time and costs are factored in
    • Time spent tying many, many knots may be undesirable
    • Joints between support sections, cords, wire, etc. can be problem areas; too meager and structural integrity fails; too robust and the wire beam weight saving concept is nullified due to heavier rope, wire, and clamps, which can crush support arms
    Aluminum Beam Pros:
    • Can be heavier duty and more robust
    • Can support its own elements and boom without support cords
    • Less affected by UV and other harsh weather in contrast to cords, wire insulation, etc.
    • Can sometimes survive heavy snow and ice more favorably
    • Possibly may more easily be used as a capacitance hat atop a tower for tower shunt loading
    • May be a better choice for towers or masts which cannot telescope, retract, or tilt
    • May be a better choice in more severe weather environments
    • Antenna does not detune when support ropes or cords become saturated with water
    • Aluminum tubing seems to respond favorably to screws, clamps, rivets, etc.

    Aluminum Beam Cons:
    • Can be substantially heavier
    • Can have higher wind loading
    • May require heavier duty masts, towers, or rotators
    • Possibly more expensive
    • May be harder to use for portable operations
    • It has been mentioned that aluminum beams may be noisier than wire beams constructed from insulated wire
    I'm sure things can be added or removed from the list or even disputed but this is just a post for discussing the various factors and it should be interesting.

    In 7 land, I've seen the snow and ice destroy a nice hex beam and the ice cords were installed. Although my home made spiderbeam was not destroyed, the same ice and snow has each year required me to make repairs to it. My experiences with both antennas have proven that they are wonderful performers on air but keeping them on air through snow, ice, and wind becomes challenging.

    Aluminum beams are not immune to snow and ice failure either. I am trying two of them presently and will see how they do. So far, the largest has survived the wind and snow just fine. I just installed the smaller one.
     
    Last edited: Nov 3, 2015
    KF5KWO likes this.
  2. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Aluminum tubing beams, well designed, can be pretty darned impervious to the environment except for salt.

    However, when ice coated they detune just like any kind of outdoor antenna will.

    I've recently used Telrex beams made in the 1950s that work perfectly and have withstood wind, snow, ice, rain, hail and everything else for over sixty years. Today they can be made better than that.

    But I don't know a way to stop the 'ice detuning' process. Ice is really the enemy of any kind of outdoor antenna.
     
  3. KM1H

    KM1H Ham Member QRZ Page

    Wire beams have had survivability issues since the cubical quad arrived in 1951. I built a well thought out and supposedly rugged 3 el tribander in 67 and it didnt survive a NH winter at 90' in a wide open former farm field, and I wound up having to remove the mess from a 90' tower on a blustery and cloudy cold March day a week before a ARRL DX contest.

    It was quickly replaced by a new Hy Gain TH6-DXX the day before the contest which survived there until 70, then 3 years on a 120' tower at the edge of miles of open farmland 25 miles west of Chicago, and then another 11 years at 100' back in NH at the lowest part in town mostly sheltered by tall pines. It finally went at 190' well up the mast on a 180' tower with a 4 el 4oM KLM down below it. This was on top of a very windy high hill.

    During this time I decided to build a contest station instead of operating elsewhere and went with homebrew 4 el monobanders in 4 high stacks for 10/15/20 on 3 towers. Once they were all up and running after 2 years of navel watching and finally a burst of decision and energy the old TH6 (it was too high for the most needed areas for high rate contesting but it could sure hear a pin drop half around the world) came down and has been up on saw horses out back ever since and never damaged by Mother Nature.

    I should sell it but more navel watching has been prodding me to convert to a TH-11 (I have most of another TH-6DXX for parts which will make the job easy and cheap) and dedicate it to the vintage tube gear station at 70-80' which now uses verticals for those bands.

    I have nothing against wire beams for performance but never again for me!

    Carl
     
  4. KM1H

    KM1H Ham Member QRZ Page

    .

    I worked thru it with a rugged manual tune amps RF to keep ice off the feedpoints and let the sun take care of the melting off the drooping elements which took under an hour. In a contest it slowed down the 20M rate but didnt stop operation. The 40M KLM's were barely bothered and the rate stayed high. By the time 10 and 15 were opening the sun had already melted their ice and 20 was running fine.

    Only the ice storm of 2008 which was a record setter in this area caused damage and those two 10 and 15 M monobanders were destined to come down anyway in a few months.The big 4el 40 and 20M stacks were already down and the ruggedized CC 40-2CD clone built from half of one of the KLM 40's wasnt even fazed.
     
  5. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Carl, ice detunes any kind of antenna but as you likely know the effect is much worse on VHF and UHF.

    I took 'first place' nationally in a few VHF-UHF contests back in the 70s and 80s when I lived in NJ and it sounds comical but in the January VHF SS I was up on the towers at midnight Friday with propane torches, de-icing spray and hammers just to get rotators to turn and hopefully knock enough ice off the antennas to get them sorta working.

    I had four 55 element yagis on 23cm and with ice on them they were resonant below 1 GHz and had no pattern at all...not good. After de-icing, they came back on line and worked. Ice REALLY impacts UHF stuff.

    I'm glad I don't have to go through that here but we do have the occasional earthquake.
     
  6. KC8VWM

    KC8VWM Ham Member QRZ Page

    Mosley seems to be the antenna of choice for hams living around here.

    We get it all here in Oklahoma.

    Every year we get at least one nasty icestorm. Sometimes more.

    Oklahoma is the last place most people associate ice storms with. But they fail to realize the climate here In the winter is just perfect for long periods of freezing rains. It gets really, really thick. Ice that's 2-5" on the tree branches.

    In the summer, every year large tree limbs falls in my backyard due to microbursts and tornadic winds. 70-80mph "winds out of nowhere" are not uncommon. I keep the chainsaw ready. Tree limbs will be falling sooner or later once again as usual.

    In fact, we had a Tornado drive through town in the spring. Not a direct hit but it still tore one of my antennas right out of the roof.

    The UV here is powerful. It peels clearcoat off cars that are only a few years old. You see this all over the place. The sun scorches fiberglass and makes it weak and brittle. This happened to my Cobweb antenna. I had to replace the rotting fiberglass after one spreader arm broke. But I have since taken it down.

    Any kind of wire Yagi constructed from fiberglass just wouldn't survive here for long.

    I don't think I would have a Yagi up all, if it was anything else but a Mosley.
     
    Last edited: Nov 3, 2015
    NH7RO likes this.
  7. WA7PRC

    WA7PRC Ham Member QRZ Page

    Going back to my Novice days in the early 1970s, I've always had some form of aluminum HF yagi. Weather in Western WA has not been an issue with survivability nor tuning. My current Force12 C-4XL 40-20-15-10m yagi has been up (above tree top height) since 2011 with zero issues.

    vy 73 es gl,
    Bryan WA7PRC
    http://www.tinyurl.com/wa7prc-tower
     
  8. AE7F

    AE7F Ham Member QRZ Page

    I'm sure it was Steve who convinced me to try a beam some years ago. That pretty much put me on the track of looking at different things and I considered a lot of antennas before building the spiderbeam.

    My first idea was to build a wire beam log periodic. I found a lot of great information on how to build one and optimize it for one or more factors. The problem there would have been the support structure although DXE or MaxGain fiberglass would probably have sufficed. However, the geometry gets interesting and boom length gets long. I may still consider building an aluminum LP at some point.

    Next idea was to build a hex beam but it didn't seem to work out favorably in terms of how it looked. That's probably the wrong antenna to start with in the looks department. However, it is a great performer and it is one of the more well-documented antennas out there and can be built in a variety of ways with different materials. I tried one here but it was destroyed in a heavy snow storm in May.

    I settled on the spiderbeam. I liked that it offered 5-6 bands on one antenna but also that it was large enough to offer very good gain and f/b ratio. I have verified its performance over the years while racking up probably 160 new entities with it. As of this time, it is the best performing antenna for HF that I have used. I built it for half of what the commercial one costs, so that 4+dBd of average gain wasn't so expensive. It was a great choice.

    However.....

    I had no idea how a wire beam would work in the weather here. Fast forward through the years and now I can say exactly how a wire beam functions in this climate. The bottom line is that every winter is somewhat of a gamble as to whether or not the wire beam will survive. The first couple of antenna iterations did not work well at all and fortunately, I started out with a crank-up mast.

    During the first winter with the crappie pole version of the beam, I awoke to find all of the spreaders and wires drooped almost 90 degrees in a big mangled mess. Fortunately, I was able to crank down the mess, shake off the snow, fix stretched support cords, etc. However, the tighter I made the guy wires, the more the crappie spreaders would retract. It was a mess and a challenging problem to fix in the 25f temperatures.

    The next spring, I replaced the crappie poles with heavy duty DXE fiberglass tube and made other improvements. However, each improvement came at the cost of more weight. Along comes the snow again and even with the new improvements, the antenna spreaders and wiring were again drooping down under the weight of the snow. Due to the heavy duty fiberglass tubing and especially, a short segment of schedule 80 PVC pipe near the hub, each spreader was able to flex appropriately without breaking. I really doubt the commercial version could have survived.

    The next spring, I made further improvements, including stainless steel hose clamps and adel clamps (p-clips) to replace zip ties, tape, rope, etc., heavier duty eye bolts, and double the amount of guy cords and ropes. The antenna grew much heavier and wind load increased but it survived all of the nastiest wind and the winter snow just fine. The antenna has for the most part been fine ever since, other than the 30m dipole wire elements breaking, some weird tuning issues on 15m, and rapidly deteriorating paint due to our intense UV radiation here.

    However, due to several factors, I have taken down the spiderbeam for now. One factor is that there is a good chance for a heavy snow year for us. Another factor is that I'm not using the crank-up mast anymore - I have a self-supporting tower. Another factor is that when I originally looked into getting or building a beam, I did not have access to or familiarity with modeling software (I do now, and there appear to be a multitude of ways to build an aluminum yagi or multiple yagis that can replace the wire beam). Finally, I had a Mosley beam sitting on the ground for awhile and simply wanted to try it. So with some effort and assistance from a good friend, the Mosley CL-33 went on the tower a couple of days ago and I am testing it now.

    I do not like giving up 12/17/30m so as discussed in other threads, I'm looking into either modifying the CL-33 to add additional elements and a new feed system, or simply stacking another antenna. The 30m dipole was too low anyway so I may just use a simple vertical for 30.

    By the way, another thing I forgot to mention about wire beams such as the spiderbeam is that they can be difficult to install on the tower. Mine snagged on every possible thing going up the tower and as a result, one of the guy cords came loose and one wire element was stretched.

    I am not discouraging anyone against using a wire beam nor am I discouraging anyone from using a hex, spider, optibeam, or quad antenna. They are amazing performers and I think they withstand wind and temperature extremes extremely well. They even survive some snow storms, just not all of them. What I am saying is that all factors should be considered.

    When all of that is taken into consideration, a wire beam looks like a great, if not fantastic option for portable or temporary ops or for warm/mild/temperate climates. But the WX in 7 land can (and often does) swing from -20f to over 100f through the year, and this naturally also means vicious winds as the seasons change (especially in the spring) and snow ice for long periods of time. So far, after at least 3 or more years of experimentation, the wire beam idea has worked but IMO has required more than average time and effort spent maintaining, repairing, or replacing.

    FWIW.
     
    Last edited: Nov 3, 2015
    KF5KWO and KC8VWM like this.
  9. AE7F

    AE7F Ham Member QRZ Page

    Interesting, Charles. I didn't know your weather was potentially that poor.

    Well, my TA-54 has been fine in the weather so far. Continuing to watch it but it is seriously built like a tank and I have no expectation of it failing. I know traps can have their issues but that beast is on an MA-40b with winch, so it's not a big deal to lower it.

    I heard a ZS3 station on 20m this morning on the CL-33 but didn't get there in time and he was gone.
     
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  10. KC8VWM

    KC8VWM Ham Member QRZ Page

    Looks like I missed him too. :)

    I have nothing against wire beams, it's just that they are not for me. At least not here in this grid sector of the country.

    Good luck with the CL-33.
     

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