On Wed, 22 Jan 2014 15:32:31 -0700, "Irv Finkleman"
wrote:

Q. Is there a relationship between the efficiency of an antenna and the
received signal strength?

Not really. Radiation efficiency is normally used with transmitting
antennas, not receiving. You're not radiating anything in receive.
http://en.wikipedia.org/wiki/Antenna_efficiency

Just pondering on the matter. Because I have to operate with
restricted space antennas, usually with low efficiency, I wonder how
much of a relationship exists between Efficiency and Received Signal
Strength?

Any loss of receive efficiency will show up in the antenna gain (or
lack of antenna gain). No need to deal with it separately.

This may help with conversions and computations:
http://www.tscm.com/fieldint.pdf

This leads to more questions such as how much do radials contribute
to efficiency?

I assume you mean ground radials, not antenna radials. The purpose of
the ground radials is to prevent the RF that's being radiated towards
the ground, from getting absorbed by the ground. With above ground
radials, they reflect the signal upwards, so that part of the signal
goes in hopefully some useful direction. (Note: This is not the
conventional wisdom).

IF that isn't enough, how much do radials contribute to the bandwidth?

That's what antenna models and simulations are for. Much depends on
the conductivity of the ground, the size and number of radials, type
of antenna, etc.

I'm never to old to learn, but I am old enough that a lot of mathematical
mumbo jumbo and Smith Charts tend to confound me!

See:
http://www.qsl.net/4nec2/
or
http://www.eznec.com
Both come with a large collection of ready to play antennas. Take
your location, your antenna, your ground, and your imagination, and
make a model. I've done that for my house. It started out fairly
simple, and has grown into a monster that takes hours to compute.
Still, it's quite worthwhile to see what changes, such as your ground
system, does to the pattern, gain, bandwidth, vswr, etc.

Incidentally, you can have:
Gain, bandwidth, or size. Pick any two.
What that means is that if you shrink the antenna, you're going to
lose either gain or bandwidth. No free lunch in antenna land.

For starters, I will be operating using an MP-1 antenna and a Yaesu
FT-817ND. I also have an MFJ-931 Artificial Ground, but propose
attaching the radials to the feedpoint on the MP-1. I intend to cut four
radials for 20M and spread them around the base of the antenna in
my room, and once the weather warms up, I'll try the antenna out on
the balcony with the radials spread around whatever real estate it
provides.

Sorry, no clue to what it will do. I convinced a friend to run his
2nd floor station with some welded fence wire under his carpet. It
worked fine until his wife made him remove the wire. Nothing would
roll over the carpet.

Thanks for any input on the matter....

Never thank anyone until it's done and working. Premature thanks is
bad luck.

Irv VE6BP
RADIATE OR DIE TRYING!

Calculations are worth more than the usual cut-n-try.

--
Jeff Liebermann
150 Felker St #D http://www.LearnByDestroying.com
Santa Cruz CA 95060 http://802.11junk.com
Skype: JeffLiebermann AE6KS 831-336-2558