[SCCC] K7JA's broadband, ladder-line fed dipole ANT at Visalia?

[Bill Haddon]

One further note on the DE Zepp for 40m:

By placing capacitance in both legs of the dipole, the beamwidth of the
main (bidirectional) lobe can be increased from about 35 deg to about 45
degrees without significant loss of gain, at the same time reducing the
four side lobes (50 deg off center, 8 dB down) of the DE Zepp.  This N6LF
mod is described on page 6-13, 14 of the ARRL Ant Handbook (N6BV Ed) 21st
edition.

It is probably important to have these antennas rather high off the ground
and flat-topped (not inv V) for these "fine point" adjustments to be
important.

While in Marin country, I compared the 20m DE Zepp to a full sized 20 m
beam; for domestic signals. The DE Zepp was often better, perhaps because
of higher radiation angle (?).  The 20m DE Zepp was a fair performer on 40m
at a height of 45 feet over average to poor conductivity terrain; raising
it to 75 feet gave an amazing improvement in performance.

One final note:  with the current 40m DE Zepp at about 75 feet, the 80 m
performance on the East Coast is spectacular. N4AF, who participates in our
NS contests, commented "Bill whatever you do, don't change your 80m
antenna".  Often this antenna out-performs or equals N6RO's 4-square on
80m.  ( But using a 650 foot ENE Beverage for receiving).

73  Bill n6zfo

On Sat, Jun 9, 2012 at 9:39 AM, Bill Haddon <haddon.bill at gmail.com> wrote:

> The K7JA antanna is a Zepp antenna, as described in Chapter 8 of the ARRL
> Antenna Handbook, N6BV Ed.
>
> i.e. a center fed wire using 450 or 600 ohm ladder line into a tuner with
> an appropriate Balun.
>
> If each leg of the Zepp is around 0.64 wavelength the broadside
> (bidirectional gain) increases to about 5 dBi (3dB gain over a dipole).
> Thus a 20m DE Zepp has an overall length, in feet, of 1.28 * (468/14.1) =
> 42.5 feet (probably not to critical).  That length, which is close to the
> K7JA's 40 feet, will give excellent performance on 20m and very
> satisfactory performance on 40 m.  It can be loaded on 80m with a good
> tuner. The 3dB points (in DE Zepp configuration) are about 15 deg either
> side of center  vs. about 45 deg for a standard dipole.  So if optimized to
> the East Coast, it will may not be so good for Europe, but will be ok for
> ZL/VK and N. Africa.
>
> I'm currently using a 40m DE Zepp at about 75 feet.  For domestic contests
> it's performance if outstanding on both 40 and 80 m and v. good on 30m.
>
> If you're just using this type antenna as a 2nd antenna for contests, it
> may be best to avoid the DE  Zepp length so broaden the coverage.
>
> There could be increased noise pickup on the feedline. Better to use Bev.
> receiving antennas if you have the real estate.
>
> Using this type of antenna for20, 40 and 80m Q's I've had several Pacific
> div wins in ARRL SS, low power.
>
> 73 Bill n6zfo
> (NCCC)
>
>
>
>
>
>
> On Fri, Jun 8, 2012 at 12:55 PM, H Lawrence Serra <hlserra at sbcglobal.net>wrote:
>
>> Did anyone take notes on Chip K7JA's broadband, ladder-line fed dipole
>> ANT talk at Visalia? I think it was about 40 ft each leg, fed by a certain
>> length of ladder line fed to an ANT tuner. Chip suggested it as an
>> emergency ANT or a supplemental contesting ANT for directions 90o to your
>> beam heading.
>>
>> 73, Larry N6NC
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>
>