Re: End Fed antennas w/ uBITX #ubitx

Jerry Gaffke
 

If you are into placing your radiation pattern exactly where you want it with a big yagi,
then a multiband wire antenna is not for you.  Agreed.

But many hams are putting up a wire dipole as best they can fit it on the lot
into what trees are available.  The radiation pattern is what it is. 
An EFHW at the fundamental can work about as well as the more typical dipole
with the same radiation pattern, and is easier to put up for mechanical reasons.
As a bonus, in my experience it can work very well as a multiband antenna as well.
The many lobes at the harmonics actually are not a negative, the dipole isn't 
efficient all directions either.   Most of us don't have a rotater for our 80m dipole. 
Fundamental or harmonics, I'm primarily concerned that it radiate efficiently.
If it happens to have a pipeline into Timbuktu and not LA, I'm fine with that.
If you don't like the direction it is pointed, try another band and it's a whole new ball game.

Trying to make an EFHW into an efficient multiband antenna can be tough.
That's why this thread now has 250+ posts.
Rather than kick off another storm of posts here, I'll just suggest you read
the EFHW-8010  review in the March 2016 edition of QST.
That review squares well with my experiences of that particular antenna.
       http://www.arrl.org/files/file/ProductReviewsForDeb/2016/pr032016.pdf

Jerry, KE7ER



On Mon, Jul 30, 2018 at 01:44 PM, Chuck, N1KGY wrote:
Agreed on both comments.  Pursuit of the "All Band Antenna" is the albatross around the neck of many newer hams, and many OMs as well.  The antenna with the least design compromises tend to cover only one band, i.e. a dipole or a (full sized) 1/4 wavelength vertical.   Can either of these antennas operate (present a reasonable VSWR, and thus 'take power') on other bands, i.e. the 3rd harmonic?  Certainly.  But if we don't examine the radiation pattern produced by said 'harmonic operation' then the utility of the antenna remains undefined, beyond the anecdotal declarations that such antennas "work" for that operator at his/her installation. 

Defining your Use Case is foundational to qualifying your results, and yet most hams  - whether they formally develop their antenna requirements at all - don't state what those requirements are.  E.G. NVIS and DX are, essentially, orthogonal propagation modes - an antenna well-suited to one of these modes is almost always a disappointment when examined with regard to it's utility for the other.  The ubiquitous failure by most hams to declare the use case(s) and/or other bounding parameters they are working under, makes antenna design and construction appear more like alchemy than science, but it doesn't have to be that way.

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