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

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?

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

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

And...

And...

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!

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.

Thanks for any input on the matter....

Irv VE6BP

RADIATE OR DIE TRYING!

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

Irv,
The very best advice we can give you is to advise you to find a good amateur radio club in your neighborhood and have you join.
Look for someone more knowledgeable then yourself - regardless of their age, and have them mentor you.
A decent Amateur Radio Club will have a hamshack - a place where it's members can operate.
There - you can take your radio and hook it up to their antenna's and operate.
The only other advice I can give you is to tell you to move!

Amateur radio isn't for everyone.
It does not allow us to bend or break the rules of Physic's.
There is a certain amount of effort that has to be done in order to get your signal up in the air and be able to broadcast it to the world.

The only option I have seen that was somewhat successful was a operator that bought Hamsticks and fabricated a mount, mounted the hamsticks on his porch railing, grounded the railing and used the hamsticks on 6 and 10 meters. 10 meters only requires a 9' long antenna - quarter wave, and a dipole on 6 is 9' long.

Your transceiver is marginal at best, not a real good performer to start with and handicapping it by using a non resonant antenna is only going to impede your amateur radio hobby much past listening to the bands.

On 1/22/2014 5:32 PM, Irv Finkleman wrote:
Q. Is there a relationship between the efficiency of an antenna and the
received signal strength?


Definitely. Antenna efficiency works both ways - a less efficient
antenna will affect both transmit and received signals.

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?


Just as much as between efficiency and transmitted signal strength.

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


That depends on a lot of factors such as number of radials, length,
height above ground and ground conductivity, for start. Each situation
is different. But generally, for antennas such as 1/4 wave verticals,
radials will help.

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


See above.

And...

And...

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!


Unfortunately, the only way to predict how an antenna is going to work
in a specific situation with any accuracy is with math and Smith Charts.
So you can use the "tried and true" method - put it up and see what
happens

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.


Not an ideal situation, but you do what you can.

Thanks for any input on the matter....

Irv VE6BP

RADIATE OR DIE TRYING!









--
==================
Remove the "x" from my email address
Jerry, AI0K

==================

"Irv Finkleman" wrote in message
...
Q. Is there a relationship between the efficiency of an antenna and the
received signal strength?

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?


Most of your problem is not going to be with the receiver. I am thinking
that Yaesu is around 5 watts or less. For the most part you can just throw
out any kind of antenna and hear lots more than you will be able to work
with 5 watts. You can probably stick 10 to 15 feet of wire in the back of
the rig and hear as much as you can with the MP-1 antenna in the same room.

First I would get rid of that rig and get one with 100 watts out. Not that
you can't work stations with 5 watts, but you will make many more cotacts
with around 100 watts on a miminal antenna.

For the antenna put up anything you can. You may need a good tuner to match
the antenna. You did not say if you are in an apartment on a high floor.
If so, stick up what ever you can vertical and load it with a coil if
needed, and drop a wire toward the ground for about 1/4 wavelength.

Forget about really trying to chart and graph any antenna for your
situation, Just throw up something and get on the air. I would almost
recommend one of the screwdriver type antennas and some wire for a ground
plane or lower part of a dipole for your situation. For 20 meters and up
you may give a dipole made out of 2 of the Hamstick type antennas a try.




---
This email is free from viruses and malware because avast! Antivirus protection is active.
http://www.avast.com

Thanks for all the replys guys.

Just to set the record straight, I have been a ham for
over fifty years, and a very active member of
the local ham club for over 30 (since I moved to Calgary).
I hold an advanced ticket and am not
totally ignorant on matters re antennas. I am a darned
good tech (most of my gear was bought broken and I
fixed it up), but sometimes I need simple answers
to a few questions -- and this is the place for that!

BUT! -- for the past four years I have been in and
out of the hospital and off and on some pretty mind bending
medications -- consequently sometimes I cannot think as straight
as when I was younger, nor do I move around well. I'm not
yet demented but do admit to being crazy but not dangerous!

I am somewhat handicapped, and live in a senior's
residence. I cannot have an outside antenna other
than what I can fit on a small (6'x9' balcony. I can have a whip
sticking over the side, but I still need to remain relatively invisible
(all I tell the other residents is that it is for
listening to shortwave lest I be blamed for non-functioning
TV remote controls, cordless phones with low batteries, and the like).

I plan to build a magnetic loop this summer, but winter hangs around
here until about the end of May! In the meantime I am trying to figure
what I can do to operate from within the confines of my studio
suite -- once the loop is built I can put it on the balcony and tune it
remotely from inside. I intend to operate QRP using an FT-817ND.
Once I find I can operate undetected, I also have an FT-857 and may
go to a few more watts.

Insofar as radials are concerned, they will be laid around the base
of the antenna, mainly for the purpose of getting the best match
possible for the MP-1 vertical antenna, or any other things I may
try in the future. I've had a number of suggestions to use hamsticks
in a dipole configuration (won't fit on the balcony and makes
band changing difficult), baluns (not required with the whip or a
magnetic loop), higher power to overcome antenna inefficiency, and
how easy it is to learn to use a Smith Chart, and even move. I'm
where I plan to stay (I get great medical care here, and the
nurses are cute -- when I leave, they'll have to carry me out. So,
as I've said before, it's a case of 'RADIATE OR DIE TRYING!'.

Suggestions that I go to higher power, buy a screwdriver antenna, and
hints about baluns, don't help -- I've got to make do with what I
have on hand, and I will do it. My main question asking whether there
is a relationship between antenna efficiency and received signal
strength (will a more efficient antenna result in a higher S-meter
indication?) is all I really wanted to ask. The radial matter was
simply a possible way to increase the efficiency (by reducing ground
losses). Power-wise is not a problem for me -- it's not a matter of
contact quantity but quality. It's sort of like fly-fishing versus
the dynamite fishing lure. If I get one good QSO a day, I'll be
happy.

I have trouble moving around physically so that's why I'm so slow
in collecting the materials I need, and getting something going, but I
want to do it slowly, but surely. I have a couple of ham chums
who will help me as needed.

I just got enough wire to make some radials for 20M, so I'll cut and
throw them around the base of the MP-1 and see what I can do.
Eventually I'd like to work 80 thru 10M but that's for later.

Thanks for your replies and suggestions, many of which have been
helpful, but bear with me -- I'm getting there slowly, and with
a little luck the end is in sight! It's just that I can't do anything
very quickly, but with time I'll do it all!

73

Irv VE6BP

On 1/22/2014 4:32 PM, Irv Finkleman wrote:
Q. Is there a relationship between the efficiency of an antenna and the
received signal strength?

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?

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

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

And...

And...

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!

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.

Thanks for any input on the matter....

Irv VE6BP

RADIATE OR DIE TRYING!







Irv, I have a pdf file about ham antennas that is written in very nice
plain language and explains all the benefits and downfalls of different
types of antennas and grounds. If your email is correct I will send it
to you.

Michael

I'm sorry Jerry, but you don't know what you are talking about.

Smith Charts do not have anything to do with antenna efficiency or resonance.
The only thing that Smith Charts does is explain what is happening inside of a piece of coax X inches long. Note I do not use feet - since that is too vague.

On Wednesday, January 22, 2014 4:32:31 PM UTC-6, Irv Finkleman wrote:
Q. Is there a relationship between the efficiency of an antenna and the

received signal strength?

Signal to noise ratio, very little. Received signal level vs
a more efficient antenna, can be quite a bit. But if the s/n
is appx the same, no biggie.. Lower level on the S meter, but
things should sound about the same when listening to it.





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?

It all depends what freq, type of operation, etc.. But for general
skywave HF, even a fairly inefficient antenna can be quite fine
for receiving in many cases. The level may drop with the inefficient
antenna, but assuming the same basic pattern, the s/n ratio should be
pretty much the same. If you have enough antenna to increase the
background noise when connecting the antenna to the radio, it should
be fine for general gov use.




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

to efficiency?

Quite a bit, but that's much more a transmitting concern than receive.




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

In general, adding more radials will decrease the bandwidth.



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.

You would be much better off ditching the vertical idea, and
try to figure out a way to string up a simple dipole for
one of the higher bands.

If you have room for radials, you should have enough room for
a simple dipole. And it doesn't have to be inline, or in any
particular orientation. For 20m, you could have a feed point
in one of the corners of a room, and have one 16 ft leg running
along one wall, and have the other leg running down the other
wall. The legs would be 90 degrees apart, but will still work
fine overall. The antenna will be efficient if fed with thin coax,
and likely beat the pants off most small vertical rigs.
But this sort of assumes there is not wiring or metal in the walls
to grossly detune the antenna.
In your case, receiving should be no problem. Even a length of
random wire will work for general HF. Your real issue is radiating
enough RF for people to hear you.

One thing about "short" verticals. A good ground/radial system is
more critical for those than it is for full length monopoles which
can often get by with no/few radials and still work well enough to use.
That's much harder to do with a very short loaded vertical.

If I were you, I'd be trying to find ways to run sneaky dipoles.
You could use real thin wire if needed to make it less visible.
If you stick to the higher bands, they won't be too long.
You can do 10m nicely if you can find a way to string up 16 ft of
wire total. Even a 32 ft 20 m dipole can be fit into many rooms.
Feed with thin coax, and no tuner, no tuner loss, and the efficiency
will be high. That's what you want with QRP.

Thanks Mark -- you answered my questions. I sort of knew the
answers but needed confirmation in my own mind.

If you read my post in the topic 'antenna theory made easy' you will
understand why dipoles are out of the question. Real Estate is my
limiting factor! A magloop will be built and should be running early
this summer -- earlier if weather permits!

Irv VE6BP