On Fri, 21 Nov 2003 16:58:40 -0600, "Stinger"
wrote:

|Homeowners associations are a good thing! They are basically an agreement
|that you and your neighbors will follow some clearly defined rules for the
|specific purpose of maintining optimum property values for everyone. In
|other words, you won't have to worry about buying an expensive house and
|having your next-door neighbor decide to use his yard to store a dozen
|wrecked automobiles while he builds a hot-rod or runs a car-repair business.
|Common sense should tell anyone that their rights end when they start to
|infringe on anyone else's, but sometimes you need it in writing. ;^)

I happen to subscribe to Fine Homebuilding Magazine and in one of the
latest issues there is some discussion about people who will not make
any changes to their house without considering resale value. They
could be eight feet tall and planning to remodel the kitchen, but will
they think of raising the height of the countertops to make it easier
on themselves? Nooooo. It will affect resale value. They might be
planning to die in the house but they worry that their heirs will have
a hard time selling.

The same mentality prevails in people who willingly submit to the
whims of the homeowners' association board. If I want to leave my
garage door open while I use my woodworking tools or work on my car, I
don't want the guy across the street getting his panties in a bunch
over it. Likewise, I don't want to be told when to mow the grass.

Of course, in my case, across the street is 80 acres of Sonoran Desert
and my landscaping is whatever grows here. (I gave the lawnmower to
the guy that bought my last house.) And I'm not trying to keep up
with Jones either because where I live, *I'm* Jones. Heh heh.

|
|Receiving antennas are easily concealed. If you can find mine from the
|street, you were born on Krypton. I think this is an overly-hyped problem.


If you don't want to hear anything, by all means conceal your antenna.
Antennas are reciprocal, if they wouldn't work well for transmitting,
they will work equally poorly for receiving.

|
|Broadcasting antennas are another animal, though.

Broadcasting is done by broadcasting stations. Broadcasting is
one-way communication.

Hobbists; licensed radio amateurs (hams), and CBers (not to be
confused with hams) are operating transmitting stations designed for
two-way communications.

|For instance, nobody
|wants to live next to some clown running a bunch of linear amps through a CB
|"base station."

Nobody? That is an all-encompassing term. "Few", "some", "not too
many" might be better. Not that I'm in favor of CBers running illegal
stations.

|It will literally be "seen" on well-shielded cable
|television connections, and is a nuisance.

A "well-shielded" system will not "see" anything of the sort. The
problem will more likely be from some upstanding homeowner, who
wouldn't dare leave his garage door open and violate association
rules, making an illegal tap on the cable.

| I think that's a lot of what the
|"external antenna" rules are meant to curb.

No, most antenna restrictions have nothing to do with the possibility
of interference. The restrictions are for the same reasons as not
wanting the garage door open, the grass an inch too high, painting the
house the wrong shade of white, etc...

In article , "Wes Stewart"
wrote:

Antennas are reciprocal, if they wouldn't work well for transmitting,
they will work equally poorly for receiving.

The reciprocity principle is usually good physics (but watch out for
Faraday rotation). However, the engineering virtues of a good transmitting
and good receiving antenna are different. At HF and below, efficiency is
much less important for receiving than it is for transmitting. The reason
is that the natural noise level is high at these frequencies: at 10 MHz
it's 30 dB above thermal, while a good receiver's noise floor is 10 dB
above thermal. This leaves plenty of room for inefficiency without SNR
degradation. At lower frequencies the natural noise is higher. In practice
10 meters of untuned inverted L into a 500 ohm input suffices to reach the
natural noise floor from 100 kHz to 30 MHz with a good receiver.

Back in the days of the omega navigation system, we used tuned 2 meter
whips to receive signals from around the world in the 10 kHz band.

For the results of quantitative engineering calculations on this subject,
see:

http://anarc.org/naswa/badx/antennas/SWL_longwire.html

--
| John Doty "You can't confuse me, that's my job."
| Home:
| Work:

Wes Stewart ...

^ Antennas are reciprocal, if they wouldn't work well for
^ transmitting, they will work equally poorly for receiving.

I don't believe that. It's been my experience that an antenna used for
receiving will function satisfactorily over a much broader range of
conditions (environment, antenna length, etc.) than it will if used for
transmitting under those same conditions.

Frank

Believe what you will, the law of reciprocity will ignore your beliefs and
continue to function.

"Frank" wrote in message
news:01c3b0a2$989de120$0125250a@cqvdqntcxxawvjpo.. .
Wes Stewart ...

^ Antennas are reciprocal, if they wouldn't work well for
^ transmitting, they will work equally poorly for receiving.

I don't believe that. It's been my experience that an antenna used for
receiving will function satisfactorily over a much broader range of
conditions (environment, antenna length, etc.) than it will if used for
transmitting under those same conditions.

Frank

In article , "w4jle" W4JLE(remove this
to wrote:

Believe what you will, the law of reciprocity will ignore your beliefs
and continue to function.

1. It's only a "law" for scalar radiation (like sound), not vector
radiation (radio). To be sure, it's a fine approximation for most HF
antenna systems, but watch out a microwave frequencies, especially if your
antenna system contains a "circulator".

2. In the cases where reciprocity applies you would be correct to say that
it requires that the antenna directivity and efficiency are the same for
transmitting and receiving. It does not follow, however, that a poor
transmitting antenna is necessarily a poor receiving antenna. Efficiency
matters much more when transmitting than it does when receiving.

Franks's observations are correct, and can be verified if you do a
detailed signal to noise calculation. You could also try the experiment
yourself.


"Frank" wrote in message
news:01c3b0a2$989de120$0125250a@cqvdqntcxxawvjpo.. .
Wes Stewart ...

^ Antennas are reciprocal, if they wouldn't work well for
^ transmitting, they will work equally poorly for receiving.

I don't believe that. It's been my experience that an antenna used for
receiving will function satisfactorily over a much broader range of
conditions (environment, antenna length, etc.) than it will if used for
transmitting under those same conditions.

Frank



--
| John Doty "You can't confuse me, that's my job."
| Home:
| Work:

On Fri, 21 Nov 2003 23:17:33 +0500, "John Doty" wrote:

|In article , "w4jle" W4JLE(remove this
|to wrote:
|
| Believe what you will, the law of reciprocity will ignore your beliefs
| and continue to function.
|
|1. It's only a "law" for scalar radiation (like sound), not vector
|radiation (radio). To be sure, it's a fine approximation for most HF
|antenna systems, but watch out a microwave frequencies, especially if your
|antenna system contains a "circulator".

Heh heh. When the guys from MIT come out to argue with you, you know
you're in trouble. But fools rush in...

I have made thousands of measurements in anechoic antenna ranges and I
have never seen a difference between measuring s21 and s12. (Without
the circulators, and accounting for mismatch effects of course)

Where did I go wrong?


|2. In the cases where reciprocity applies you would be correct to say that
|it requires that the antenna directivity and efficiency are the same for
|transmitting and receiving. It does not follow, however, that a poor
|transmitting antenna is necessarily a poor receiving antenna. Efficiency
|matters much more when transmitting than it does when receiving.

It also does not follow that a lousy receiving antenna is good enough.

For example, I *always* got better moon echos on 2-meter EME using the
same antenna for transmit and receive. When I tried a wet string on
receive I didn't hear nuthin' g

I have observed the same on 20 meters. My Yagi at a modest height of
50 feet is *always* better than an indoor wire.

|
|Franks's observations are correct, and can be verified if you do a
|detailed signal to noise calculation. You could also try the experiment
|yourself.

Two experiments cited above.

In article , "Wes Stewart"
wrote:

Heh heh. When the guys from MIT come out to argue with you, you know
you're in trouble. But fools rush in...

I have made thousands of measurements in anechoic antenna ranges and I
have never seen a difference between measuring s21 and s12. (Without the
circulators, and accounting for mismatch effects of course)

Where did I go wrong?

You didn't ionize the air in the range :-)

Seriously, for your purposes you did nothing wrong. Just don't call
reciprocity a "law", OK? It's a useful idea of wide applicability, but
physics does not require it in general. Calling it a law confuses people.

Many years ago in grad school my advisor would vex visitors to his office
with a little disk that looked like a piece of tinted glass. Put a quarter
on the table, put the disk on top of it, the quarter looks black. Flip the
disk over, put it back on the quarter, the quarter looks shiny. What was
the construction of this thing? Some world class physicists couldn't
figure it out.

|2. In the cases where reciprocity applies you would be correct to say
that
|it requires that the antenna directivity and efficiency are the same
for
|transmitting and receiving. It does not follow, however, that a poor
|transmitting antenna is necessarily a poor receiving antenna.
Efficiency
|matters much more when transmitting than it does when receiving.

It also does not follow that a lousy receiving antenna is good enough.

For example, I *always* got better moon echos on 2-meter EME using the
same antenna for transmit and receive. When I tried a wet string on
receive I didn't hear nuthin' g

Directivity matters equally for receiving and transmitting. Was your wet
string as directive as your other antenna? 2 meters is also quiet enough
that there's not much room for inefficiency: in some directions the sky
temperature is 200K.


I have observed the same on 20 meters. My Yagi at a modest height of
50 feet is *always* better than an indoor wire.

Throw a thin wire with dark brown insulation over a tall tree, up over one
side, partway down the other (shaped like a "?"). Tie it in place with
nylon fishing line. It will be invisible unless you're very close. Couple
to coax with a grounded 9:1 broadband matching transformer. Bury the coax
run to the house.

Not only will this be much less conspicuous than a Yagi, but it will
outperform your Yagi as a receiving antenna for nearly every signal over
the range 100 kHz - 30 MHz. A Yagi is just too specialized an antenna for
a listener.

A trailing wire under sea water receives just fine at ELF and doesn't
work worth a damn for transmitting. But those are special cases that
can always be manufactured. Beverage antennas are also not something to
be used for transmitting but you won't be disguising one as a chimney
cap either

For the listener from ELF to HF these are not manufactured special cases,
they are the general case. MW and tropical band listeners often target
their regions of interest with Beverages, either temporary or permanent. A
Beverage is another antenna that can be very inconspicuous: if your soil's
dry you can even bury a Beverage! For listening, a simple broadband
antenna like a Beverage is much more practical than a complicated
narrowband antenna like a Yagi.


In the general sense of h-f to microwave, I stand by my claim.

For the special case of confinement to a small number of narrow bands (as
in ham radio), you are reasonably correct above 10 MHz. To me as a
hobbyist listing to LW/MW/SW, that isn't the general case. Of course the
game changes when I'm operating a satellite, but that isn't my *hobby*.

--
| John Doty "You can't confuse me, that's my job."
| Home:
| Work:

On Sat, 22 Nov 2003 10:23:52 +0500, "John Doty" wrote:

|In article , "Wes Stewart"
wrote:
|
| Heh heh. When the guys from MIT come out to argue with you, you know
| you're in trouble. But fools rush in...
|
| I have made thousands of measurements in anechoic antenna ranges and I
| have never seen a difference between measuring s21 and s12. (Without the
| circulators, and accounting for mismatch effects of course)
|
| Where did I go wrong?
|
|You didn't ionize the air in the range :-)
|
|Seriously, for your purposes you did nothing wrong. Just don't call
|reciprocity a "law", OK? It's a useful idea of wide applicability, but
|physics does not require it in general. Calling it a law confuses people.

I never made that statement.

[snip]
|
|Directivity matters equally for receiving and transmitting. Was your wet
|string as directive as your other antenna?

I don't know. Remember I live in the desert; I couldn't keep the
string wet long enough to find out.

|2 meters is also quiet enough
|that there's not much room for inefficiency: in some directions the sky
|temperature is 200K.

Yep. Love that quiet sky.
|
|
| I have observed the same on 20 meters. My Yagi at a modest height of
| 50 feet is *always* better than an indoor wire.
|
|Throw a thin wire with dark brown insulation over a tall tree, up over one
|side, partway down the other (shaped like a "?"). Tie it in place with
|nylon fishing line. It will be invisible unless you're very close. Couple
|to coax with a grounded 9:1 broadband matching transformer. Bury the coax
|run to the house.

Tall tree? What's a tall tree? The best I have is some 35 foot tall
Saguaro cactii. They're a bitch to climb, although when the coyotes
went after the cat, she managed. Let's see, I could tie a string to
the cat's tail and find a coyote.....

[snip]

| In the general sense of h-f to microwave, I stand by my claim.
|
|For the special case of confinement to a small number of narrow bands (as
|in ham radio), you are reasonably correct above 10 MHz. To me as a
|hobbyist listing to LW/MW/SW, that isn't the general case. Of course the
|game changes when I'm operating a satellite, but that isn't my *hobby*.

See, one of the groups this got cross-posted to is an *Amateur Radio
Antenna* group. I'm reading and writing it from this group and
commenting from that perspective. I normally don't cross post but did
the first one by accident and since I've developed such a loyal
following I didn't want to lose anybody G.

Regards,

Wes Stewart, N7WS

The difference between "satisfactory" in receiving and in transmitting antennas
is that in receiving, one just needs an antenna that provides signals strong
enough over the on-frequency noise for the receiver to process.

In transmitting, the output has to be a strong as possible to be above the
noise in the desired receiving location. A better antenna will increase the
transmission's erp toward the desired direction.

In summary:
For better reception, put your money into the receiver.
For better transmission, put your money into the antenna.

Bill, K5BY

WShoots1 wrote:

The difference between "satisfactory" in receiving and in transmitting antennas
is that in receiving, one just needs an antenna that provides signals strong
enough over the on-frequency noise for the receiver to process.

In transmitting, the output has to be a strong as possible to be above the
noise in the desired receiving location. A better antenna will increase the
transmission's erp toward the desired direction.

In summary:
For better reception, put your money into the receiver.
For better transmission, put your money into the antenna.

Bill, K5BY

I certainly believe in buying a nice receiver, but honestly, the difference in performance I got switching from a horizontal loop near the house to a "Doty style" antenna that's 225 feet away from the house was more dramatic than you'd find if you compared
the performance of my best military receiver with a decent portable if they both used the same antenna.