[SECC] Simple Antenna for 6 Meters that Works

[Ed]

Tommy wrote:
> otherwise. But one must read the analysis quite carefully. As in the
> case of Jeff's appropriately referenced web page, Cebrik's 'max gain'
> is measured in tenths of dB's, typical differences of max gain for
> various physical configurations are calculated to be from 0.01dB to
> 0.10 dB, which in reality does prove which physical configuration
> provides 'max gain'.

>From the charts I saw, Cebik referenced his antennas to DBI, not DB.
And quite frankly, they offer only about 3 DB at their maximum to that
of an ordinary dipole. 

> What one must realize is that calculated 'max gain' and physical
> reality seldom become practical. For instance, Cebrik is showing
> element lengths, in inches, out to six decimal places, ....

This is where 1 tool is invaluable.  For some antennas, you MUST have
a rule calibrated in millimeters. I bought a metal one ( 1000 mm long
)
from McMaster Carr ( think it was about $150 ) and one can easily read
the scale down to less than .5 mm. It was used to set the lengths of
all of my long boom yagis.

> I scour through Cebrik's web site quite often to obtain ideas for
> antennas. His site is where I discovered a two element Extended
> Double Zepp yagi, which EZNEC shows to have a whopping 14.7 dBi gain.
> But for 20m, have you ever tried to hang two #12 wires, each 88' in
> length, spaced 8' apart in trees, and keep the elements carefully
> aligned?
Tommy, you have me here. What is the "spaced 8'" pertain to. And
perhaps on a point of interest, a Zepp as described is an Extended
Zepp, not
a Extended Double Zepp, which requires 2 wire sections on each side,
with appropriate phasing lines. ( I use 450 ohm open wire line ) If
the
antenna is then fed in it's center point with another section of open
wire line, of X length, and the bottom ends connected to a balun, you
may achieve almost a perfect match to 50 ohm line.


Ever tried pointing a 33 degree beam width where it  provides max
population coverage into Europe?


This is a very good point. I believe from memory that our heading to
EU is about 57 degrees. So, that gives us a good starting point. 
However, and this is a problem I am still studying, what is the
optimum
take off angle for such an antenna? Most books or authors state that
over 90% of the times, the arrival signal from EU is 20-23 degrees.

How do we balance that? Ideally, we should use a height which at it's
low -3db point results in a single hop touching down in G land. If we
then take the high -3db point, we can plot a pretty good "footprint"
into Europe.

But, contrary to most beliefs, I learned long ago that "higher" is NOT
better. Certainly, we could place the antenna at a height in the
preceding paragraph, but without even looking, I can guarantee you
will have multiple high angle lobes, and the power at the feed point
of any antenna is divided equally among all lobes. So you have a TO
angle at 10 degrees...Just how much of that KW goes into the low lobe.
About
250 watts.   

BTW, Jeff apparently overlooked the advantage of using a plain 1/4
electrical wave of RG-11 to feed that antenna. I think he mentioned
an impedance of 115 ohms. That 1/4 wave would give you 115/100 or an
indicated SWR of about 1.15:1

Really good posting Tommy.

73
Ed