rocky wrote in
:

In article ,
Dave Oldridge wrote:

Big Endian wrote in
:


My center of a 3.8 Mhz doublet is at about 35 feet and am going to
drop the ends from 30 feet to about 10 to 15 feet. Just wondering
if it will make all that much difference if any?

There will be a marked improvement in the low angle performance in
the direction off the ends of the antenna (the flattop is very poor
at this). This will come at the expense of a sight loss (about .8db)
off the pattern's top (where you can most afford it). You will also
experience a slight deterioration in the SWR (based on 50 ohm coax)
from about 1.34 to 2.05, easily managed by any tuner, including those
built into many radios. You will also find that you need to shorten
the antenna very slightly to maintain the same resonant frequency.

This won't make it into a superior DX antenna but it may allow you to
hear things you missed before. Basically, Bob Heinlein was right.
There ain't any such thing as a free lunch.

What I've read is that when the ends are dropped to an inverted Vee
configuration the feedpoint impedance drops closer to 50 ohms, but the
Vee bandwidth is more restricted. Hard to believe that lowering the
ends by 15 feet from 30 would make all that much difference on 75
meters.

It's only really noticeable on low-angle (about 30 degrees or so) signals
from the direction off the ends.


--
Dave Oldridge+
ICQ 1800667