EFHW for 160?

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by N9TSL, Nov 24, 2020.

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  1. N9TSL

    N9TSL Premium Subscriber QRZ Page

    Is anyone here using an EFHW on 160 and if so what do you think of it? My property is not big enough to erect a full size loop, dipole or plant ground radials for 160 so I'm restricted to using a EFHW

    What are the pro's and cons?

    Thanks and 73, Tracy
     
  2. WA7ARK

    WA7ARK Ham Member QRZ Page

  3. N9TSL

    N9TSL Premium Subscriber QRZ Page

  4. VK3YE

    VK3YE Ham Member QRZ Page

    160m has different propagation characteristics than higher bands.

    1. Ground wave is more prominent out to say 100km. Even a mediocre vertical will be better than an EFHW for that.

    2. It's not practical to get the EFHW high enough to be anything but a high angle radiator.

    Hence the EFHW will be good for distances like 100 - 500km. But poor for really close in or much further.

    An inverted L, with as much as possible vertical is a good all-round antenna for 160m. That can be an EFHW but it is preferable that you have two high supports so the horizontal section is just that and not sloping down.
     
    WD4ELG, AK5B, N9TSL and 1 other person like this.
  5. N9TSL

    N9TSL Premium Subscriber QRZ Page

    Thanks for the info. I didn’t realize the propagation would be that much different than 80.
    I’d rather build a vertical but the problem is I don’t have enough room for a set of ground radials. An inverted L also requires radials, doesn’t it? The advantage of using an efhw is I can mount it at 60’ (I realize that’s still low for 160) because I have a tower by my house and my neighbor said I can tie the other end off on her tree
     
  6. N9TSL

    N9TSL Premium Subscriber QRZ Page

    Ignore. Double posted. Dang phones
     
  7. WA7F

    WA7F Premium Subscriber QRZ Page

    I’m considering WA7ARK’s EFHW for 160 & 80 meter NVIS. If it has a high radiation angle, why would it not work well for this application on 160m? I think 80m will have four lobes so the EFHW maybe isn’t the best choice for NVIS on this band.
     
    N9TSL likes this.
  8. WA7ARK

    WA7ARK Ham Member QRZ Page

    For most hams, it is just not practical to get any (either ground-referenced Marconi or ground-independent Hertz) 160m antenna high/tall enough to get anything but high-angle, NVIS out of it...
    Yes, it is just another form of a Marconi.
    On its fundamental band, the radiation pattern of an EFHW is indistinguishable from a center-fed dipole , all other things being equal...

    You might get something out of reading my posting in this other forum thread about EFHWs, especially how to move the second and subsequent harmonic responses lower in frequency by putting a series capacitor in the wire.

    If you want, I can use the parametric model I ginned up for that other thread to optimize an EFHW to hit two resonant frequencies of your choice; one at 160m the other where you want to operate on 80m. I would need to know what type of earth is below the antenna, wire diameter, insulated or not, power level, coax length and type.
     
    WB5YUZ and N9TSL like this.
  9. N3IL

    N3IL Premium Subscriber QRZ Page

    I use a Myantennas 160-40m EFHW-16040-2K for 160m. The first 70' slopes from 25' to near 50' agl, then ~150' at 50' agl, and the remaining ~40' slopes down to 30' agl. The first 70' is in the clear, the remainder of the antenna is in woods (lots of trees). I tuned the antenna for resonance specifically on 160m with a workable bandwidth across the entire band and SWRs the internal A/T (IC-7610) can handle (SWR 2.6 at 1800, 1.6 at 1840 - by design to optimize for FT8, 2.5 at 1940 and 2.8 at 2000). RG-213 (~30') is the feed from the transformer to a Myantennas common mode choke near the shack feed-through panel; CMC to a Polyphaser lightning protector and through a feedthrough panel into the shack. For my earth ground system I have five 8' copper clad earth rods connected via #6 awg solid copper, connection to mains power earth at entry panel, and a single point connection at feedthrough panel.

    From my QTH in central-Ohio, nominal FT8 range is ~100 miles to ~1000 miles, consistently achieved (~85W); have had several out to ~1500 miles. On LSB, nominal range consistently achieved is ~80 miles t0 ~500 miles (~250W).

    The configuration is not ideal from a height above ground level though it works well enough for LSB and FT8 operations on 160m with contacts possible virtually every day (thunderstorm days excluded). Also, a great antenna for MW Dxing.

    What I've learned with wire based HF antennas (have five operational atm) - read, read, read; don't take shortcuts when erecting; use a good quality antenna analyzer in tuning; and simply try it.

    73

    Dave N3IL
     
    N9TSL likes this.
  10. W9XMT

    W9XMT Ham Member QRZ Page

    That POV of WA7ARK is totally invalid in the case of a Marconi, and to a lesser extent for an inverted L.

    All Marconi* antennas ≤5/8WL tall generate/launch their maximum relative fields (E/Emax) in the horizontal plane.

    * a vertically-oriented, monopole radiator driven against a flat ground plane​
     

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