RadioBanter - View Single Post - Let's design a short antenna just for fun

John S · November 6th 14, 04:22 PM posted to rec.radio.amateur.antenna

On 11/6/2014 7:16 AM, amdx wrote:
On 11/5/2014 1:08 PM, wrote:
On Wednesday, November 5, 2014 1:01:02 PM UTC-6,

I would think a dipole would be a bad candidate for a "short" antenna
as you need to get the matching stuff close to the antenna to avoid
I^2R losses.

I'd probably use small matching coils at the feed point, about the
same as a mobile antenna.
In the real world, I try to avoid short antennas..
It's only a last resort due to lack of room. I rarely actually use one.

OK, nuff jabbering.
I'll set the rules 15ft tall, designed for 80 meters.
16 radials, base mounted inductor and whatever tophat you desire.
Do the theoretical design find the feed impedance with some efficiency
numbers.
Then compare data to a dipole at 1/4 wave height.

Ready Set GO!

Wait, do you have a better idea than a base mounted inductor?
How long are the radials?
Do you want to compare 8 to 16 radials.
The tophat needs to survive 80 mile an hr wind.
I'm sure there's more.

Mikek

What wire material/size? Some stainless steel rods might have a
permeability that will reduce the efficiency. It will certainly have a
higher resistance than copper. Also note that copper-clad steel must
have a cladding several times the skin depth for high efficiency.

John