[Elecraft] The 20 M E-H Antenna

[James R. Duffey]

Chas - Thanks for sharing your experiences with the E-H antenna.

There is nothing magic about the E-H antenna. It is an electrically short
antenna fed in the center. One can calculate the radiation resistance and
loss resistance of such an antenna without much trouble. From these it is
simple to calculate the efficiency. The efficiency of the 20 M E-H antenna
is about 5% to 10%. I posted such calculations on QRP-L a while back when
someone suggested that the E-H antenna would perform comparably to an
inverted vee. I can reproduce them if you wish. Ed Hare made some
comparisions wiht a 40 M E-H and an inverted vee at W1AW and came to the
same conclusion.

So, I am curious as to how you calculated or measured the 95% efficiency
number for the E-H antenna that you quote. A typical dipole is about 90% to
95% efficient.

The radiation pattern for a small center fed antenna is very similar to that
of a full size dipole, varying by only a few degrees. So I am also curious
as to your comments on a narrower beam width concentrated at low angles. I
do not see how this can be achieved with the E-H antenna geometry.

It is cleat that you are happy with your E-H, but I think that most hams
would be happier with a more conventional and somewhat larger antenna.- Dr.
Megacycle K6MC/5
 
______________________
James R. Duffey KK6MC/5
Cedar Crest NM 87009 DM65