[TenTec] limited to one antenna

[Barry N1EU]

The 44ft doublet ("Norcal") is very popular in qrp circles because it is
the maximum length that will still be bi-lobed (broadside) on 10M.  It's a
great portable antenna for 40-10M fed with low loss balanced line.

Barry N1EU


On Sat, May 24, 2014 at 2:19 AM, TTMaven <jrichards at k8jhr.com> wrote:

>
>
>
>
> On 5/23/2014 8:23 PM, Paul DeWitte wrote:
>
>  As far as an 80m dipole being directional on the upper bands, if you
>> have your resonant 10,15,20m dipole up high it will also be directional
>> broadside. So what is the difference? Maybe just not the direction you
>> want.
>>
>>  _________________________________________________
>
> I take your question to be:  what is the difference between a big dipole
> that can work the upper bands, and a smaller "resonant" dipole that is cut
> for one or more upper bands, respectively.   (By "resonant"  I presume you
> mean a half-wave dipole.)
>
> Rick taught me an important lesson about long dipoles vs short dipoles.
>  Joel Hallas teaches the same lesson about big vertical antennas in his
> series of articles on vertical monopoles which appeared in a couple issues
> of the 2013 QST magazine.
>
>         The longer the element is relative to the
>         frequency, the more lobes it tends to have,
>         and the radiation pattern varies, as well.
>
> Joel Halls refers to this when he discusses the 43 foot vertical antennas
> in QST magazine last year.  At 80, 40, 20, and maybe 17 meters, it tends to
> have lower take off angles and fewer lobes.  But, as you use it on 12, 10,
> and maybe 60 meters, the take off angle rises, and you tend to get more
> lobes.   In comparison, a shorter ground plane for those upper bands will
> have fewer lobes and lower angles.
>
> The long dipoles exhibit a similar phenomenon.  As you use a very long
> dipole on the upper bands, you tend to get more lobes and a different
> radiation pattern.  In contrast, a shorter dipole, cut for each band,
> respectively, will tend to have fewer lobes and a more rounded, better
> radiation pattern.
>
> I believe the charts in Section 2.1.4  Effect of Frequency on Radiation
> Pattern (page 2-9 of the ARRL Antenna Book (22d Ed) show various radiation
> patterns for various frequencies of a fixed length dipole.  As you get more
> lobes, you lower peak gain and end up with nulls that may mean you don't
> hear the DX as well in certain directions.  Of course, some patterns may
> help matters, others will not.
>
> In Chapter 10, on page 10-20, it says about 43 foot vertical multiband
> antennas:
>
>         In recent years, the 43-foot ground-mounted vertical
>         antenna with an automatic antenna tuner at the base
>         of the antenna has become very popular as an all-
>         band HF vertical...  while the elevation angle of
>         maximum radiation begins to increase significantly
>         above the 20 meter band, the combination of
>         simplicity and clean appearance make up for the
>         compromise.  ...
>
> Joel Halls told us in his QST series of articles, that as you use those
> antennas on the upper bands - i.e. 17 meters and higher - you also get
> multiple lobes in addition to how the elevation angle rises, so you may be
> better off with a smaller, dedicated, tuned and "resonant" ground plane cut
> for the upper bands, than to try to use the big stick on the upper bands.
>  Rick has reinforced these observations for me on several occasions.
>
> Thus, while matching the antenna to the transmission line and rig is one
> important consideration, the radiation pattern is another.
>
> I think is explains the difference in the two types of antenna.  Of
> course, if you only have room for one antenna, then the long, multi band
> all-in-wonder is what you use!
>
> Happy trails.
> --------------------- JR  -----------------------
>
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