RadioBanter - View Single Post - A short 160M antenna

Wayne · November 8th 14, 09:51 PM posted to rec.radio.amateur.antenna

wrote in message ...

Wayne wrote:

"John S" wrote in message ...

On 11/8/2014 10:57 AM, Wayne wrote:

"John S" wrote in message ...
On 11/7/2014 12:58 PM, wrote:
wrote:

snip

The only downside to this antenna is that it is extremely narrow
banded, only about a kHz or so.

snip

I realized I should expand on that.

With all 5 inductors the same value the 5:1 bandwidth is about 500 Hz.

By staggering the values of the inductors in the four legs the bandwidth
can be improved by a little bit.

The best I could accomplish was about 1 Khz by making the leg values
.96, .98, 1.02, and 1.04 times the central leg value.

Going beyond a step factor of .02 made little difference in the
bandwidth
and the resonant frequency SWR started to increase.

# Okay, but the starting target was to be able to feed a short antenna #
with good efficiency and I think you hit that target. I know you want to
# keep it as practical as possible, but I am impressed with your results.

I agree. I like the approach.

Anyone ready to tackle a fractal design

# I have no idea how to approach that, but I'm willing to read your posts
# on it. Start by assuming zero knowledge for me.

That comment was made in jest, and nm5k picked up on it with his response.

Some years back there were the Great Fractal Wars (TM) on this group.
Some
of the recent comments reminded me of those days.

In summary, one poster was pushing his design of a fractal antenna and it
took hundreds (if not thousands) of posts to get him to nail him down on
the
design. It didn't seem to have any particular advantage over other
antennas, and had a more complex construction.

# He also had some "antennas for hams" on his web site, long taken down,
# that he raved about.

# Apparently he thought he was the only one with any antenna analysis
# capability.

LOL...yeah, one time I took his "fractvert", which required two supports,
and modified it to use one support.
Then I posted the EZNEC results and he got real ****y about it. Good times?