Look ma, no counterpoise! An evaluation of a EFHW-8010

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by WA7ARK, Apr 24, 2019.

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  1. K7TRF

    K7TRF Premium Subscriber QRZ Page

    The only ground you really need in this situation is a ground for the coax shield where it enters your building. Assuming you have modern wiring in your home (grounded outlets) you don't really need to run that ground strap into the shack nor ground all your equipment.

    I should save this somewhere for cut and pasting but here goes....

    There are three main reasons for grounding in a ham shack:

    - Human safety against shocks from internal equipment shorts. In modern homes this is provided via grounded outlets. If you run vintage rigs with two wire cords you can either swap the power cords for 3 wire cords and bond the green (ground) wire to the rig's chassis or you can run an outboard ground wire from the rig's chassis to the nearest outlet ground.

    - Grounding coax shields as they enter your building. The NEC requires this. Ideally this is done down at ground level and ideally you'd bond your coax shield directly to your home's AC service point ground. Alternatively you can drive a new ground rod and tie the coax shield(s) to that rod but it also must be bonded back to the AC service ground with a heavy gauge conductor. In many cases entering the home at the AC service entry point and then running coax up to your shack inside your home is a good way to go as it maintains single point grounding to your home.

    - Adding 'RF Grounds' to your shack for use with certain antennas like shack tuned random wires that need to work against a ground. Being on the second floor this will be tough but the answer is running antennas that are complete including their RF Return (aka RF ground). That could be dipoles or verticals or inverted-Ls with radials or even an EFHW as long as you take counterpoise into consideration either via the coax shield (ideally common mode choked about 5% to 10% of the longest wavelength you'll use) or with explicit counterpoise. If you run an antenna system like that you don't need an 'RF Ground' in your shack.

    Basically, point 1 is covered with modern wiring, point 2 is done outside the shack and ideally at ground level close to the AC service entry point and point 3 you shouldn't need unless you use an antenna system like a shack tuned random wire or shack tuned Windom (original single wire feed version not the modern coax antennas that have borrowed that name). Just using a shack tuner doesn't mean you need an 'RF Ground' using an antenna system that lacks some form of RF Return is what mandates the shack ground in that case if you don't want your home's ground wiring to serve that function (not a good idea).

    Basically most hams don't need to run an elaborate shack grounding system though they should adhere to the NEC and ground coax shields where they enter the home.

    There's a lot of very dated information regarding shack grounding, some still published by the ARRL and others but in the vast majority of modern ham shacks an external ground system is not needed and won't provide any benefit. If adding a shack grounding system does something noticeable to performance like reducing received noise then something is wrong with your antenna system deployment and the added ground system is a band aid, it's best to fix those kinds of problems at their source.
     
    KX4O likes this.
  2. K6BRN

    K6BRN XML Subscriber QRZ Page

    Gentlemen:

    Good ground is essential to putting up an EFHW. The logic is irrefutable:

    1. Solid ground is needed to stand on or to place a ladder on when putting up the antenna.
    2. Quicksand, which is poor ground, does not support a person or ladder very well, so antenna erection is not practical.
    3. Antenna supports or trees do not last long when planted in loose, mobile soil (as in Malibu, CA or Palos Verdes) and tend to fall to the ground.
    4. Very rocky, poor ground makes it hard to put up an antenna support and for nice trees to grow.

    This should settle the debate!

    :)

    Brian - K6BRN
     
    G5TM likes this.
  3. G5TM

    G5TM Premium Subscriber QRZ Page

    Solid advice (unlike the ground) :)
     
  4. 2E0VSS

    2E0VSS Ham Member QRZ Page

    Come back Owen (VK2OMD )and don’t deprive us your mind to sort this shambles out any any longer than is necessary.
    All the real Gurus and Elmers like Owen (above) now watch/monitor and don’t get involved anymore.
    A new breed of knowitalls now proliferate this Antenna
    forum to my mind.

    M
     
  5. K6BRN

    K6BRN XML Subscriber QRZ Page

    In all seriousness...

    Just listen to Mike, WA7ARK and download and read his packages. He has done both experimentation with and modelling of the EFHW-8010 wire antenna and his results correlate very well with my experience over several years use. In short, he's "done his homework" and "Put his money where his mouth is". Very hard not to respect that.

    He also has a good professional technical background. And I don't mean he was an electrical tech on Old Ironsides just after the War of 1812, either.

    There are other decent packages around explaining these antennas - but Mike's are about the best, IMHO.

    And ... Mike is right - these resonant wire antennas do not need a ground and do not routinely have significant common mode current issues on the coax (though we both recommend a CMC before the radio - I have them on all of my antennas). The formula for success is simple: Higher is better and distance away from major structural or conductive objects (like gutters) is GOOD. The antenna can be bent into a variety of shaps and still work well (horizontal or vertical vee, linear...), hence they fit on small/restricted lots very well. Since they are also low visibility, a number of us have used then successfully at HOA controlled homes.

    They are NOT as effective as a 3-element Yagi on a tower, but they are pretty good and about the easiest HF antenna to put up that I've ever found. When a better one comes along, I'll switch to that for my "gapfiller", portable and HOA antennas.

    The vast majority of the nay-sayers... have never used them. Some don't even operate very much or lack stations. So check the reviews on eham.net by actual users and decide for yourself. At $120-$200, they are quite affordable to most hams.

    Brian - K6BRN
     
    G5TM likes this.
  6. G5TM

    G5TM Premium Subscriber QRZ Page

    Absolutely spot on -- a great summary and correlates exactly with my experiences of using these antennas. Bravo.
     
  7. 2E0VSS

    2E0VSS Ham Member QRZ Page

    DL2kq 4 band Longwire
    (Google translate German-English)
    The most efficient way to feed a 41 metre wire element that I have personally seen.
    No ferrite involved.

    2E0vss
     
  8. K6BRN

    K6BRN XML Subscriber QRZ Page

    Hi Mark (2E0VSS):

    Good for you! Nice to have an antenna you like.

    Do you actually use it? Regularly?

    Brian - K6BRN
     
  9. WA7ARK

    WA7ARK Ham Member QRZ Page

    DL2KQ's antenna is a variant of the Zepp antenna I posted here, where the horizontal wire is 134.5ft long, and the twin-lead is 24.6ft long. His configuration is not resonant, but on five HF bands presents a real load resistance R that is reasonably close to 50 Ohms. On four of the bands (80 to 30m), the jX term can be cancelled with only a variable series (roller?) inductor (1 to 50uH). On 20m, the jX term can be cancelled only with a variable series capacitor (20 to 35pF).
    KQ.png

    It requires a manually-tuned LC network tuner (or an automatic remote tuner) that has to be placed 24ft from the antenna wire, so might be useful if your shack is on the second floor of a building (or higher).

    The net difference between feeding an EFHW wire this way compared to using a ferrite transformer is maybe 1db, so I will take the convenience of more bands, no-tune, no remote tuner, ferrite transformer approach any day...
     
    W1BR likes this.
  10. K6BRN

    K6BRN XML Subscriber QRZ Page

    Mike (WA7ARK):

    Yes... 1 dB loss is just swamped by many other factors, inlcuding propagation. It is a small mumber. And convienience and low profile is much more important in many installs - especially for new hams, those in HOAs or hams that simply need a decent band "Gapfiller" antenna

    Ummmm... quite a detailed answer in very short order. Are you planning on posting an "Antenna Help Desk" phone number? Just asking. :)

    Happy Friday!

    Brian - K6BRN
     

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