Hi all,

I wanted to build an RF relative field strength meter, so set about
searching on the Web for any existing designs. Those I turned up
weren't particularly impressive, so I decided to start from scratch
and design my own. I've just completed that this afternoon. I've
allowed for 0.25mV input to give rise to FSD on the microammeter.
Question being, however, is that going to be sensitive enough? Does
anyone have any idea what the field strength in microvolts or
millivolts is from a half Watt transmitter at about 6 feet away? I
guess I should have posed this question *before* designing it, but who
among us can honestly say they haven't designed something without
knowing what the spec is? :-)
Anyway, ballpark figures gentlemen, please.

p.
--

"I expect history will be kind to me, since I intend to write it."
- Winston Churchill

I wanted to build an RF relative field strength meter, I've allowed for 0.25mV
input to give rise to FSD on the microammeter.
Question being, however, is that going to be sensitive enough?
Does
anyone have any idea what the field strength in microvolts or
millivolts is from a half Watt transmitter at about 6 feet away?

Figuring the field strenth of a .5 W xmtr at 6 feet is difficult. Depends on
the antennas on the xmtr and the FSM and their polarization. Also, depends on
the sensisitivty of your FSM (field strength doesn't depend on sensisitivty but
your reading will).
Since this is a *relative FSM* I would get something working, use that as a
reference, and go from there.


73 Gary N4AST

Paul Burridge wrote:

Does
anyone have any idea what the field strength in microvolts or
millivolts is from a half Watt transmitter at about 6 feet away?

I'll SWAG & hope I'll be corrected if I tell ya wrong. Assuming a 1/2
wave antenna on the xmit & rcv, take the volts/meter you're applying on
the antenna, divide by 4 PI / (distance)^2, with distance being in
wavelengths.

Then there is the famous propogation equations which involves 32,
recieve and transmit antenna gains, and the log of the distance and
frequency. You can then go from power to voltage according to the
antenna Z. I'll look up the equation for you if you don't get a better
answer.

--
Scott

**********************************

DIY Piezo-Gyro, PCB Drill Bot & More Soon!

http://home.comcast.net/~scottxs/

**********************************

Scott Stephens wrote:

Scott

**********************************

DIY Piezo-Gyro, PCB Drill Bot & More Soon!

http://home.comcast.net/~scottxs/

**********************************

Your web site is very hard to read with the dark blue background and
black text. A lot of people have vision problems, and can not read this
color combination.
--
13 days!


Michael A. Terrell
Central Florida

In (rec.radio.amateur.homebrew), Michael A. Terrell wrote:
Scott Stephens wrote:

Scott

**********************************

DIY Piezo-Gyro, PCB Drill Bot & More Soon!

http://home.comcast.net/~scottxs/

**********************************

Your web site is very hard to read with the dark blue background and
black text. A lot of people have vision problems, and can not read this
color combination.

On my system (FreeBSD) with the Mozilla FireBird browser, the text
and images are in light-colored windows inside the dark background,
and it's not at all difficult to read. The Netscape 4.6 browser on
the same system _does_ put the black text directly on the dark-blue
background, and it is decidedly unpleasant.

A newer browser might be nice, but it also would be good if web page
designers built pages with older code in mind.

It _definitely_ has some cool stuff. Thanks, Scott!

--
Comparing Knuth with O'Reilly books is like comparing
Unix with Windows.
-- Abigail, in the Monastery

Mike Andrews wrote:

On my system (FreeBSD) with the Mozilla FireBird browser, the text
and images are in light-colored windows inside the dark background,
and it's not at all difficult to read. The Netscape 4.6 browser on
the same system _does_ put the black text directly on the dark-blue
background, and it is decidedly unpleasant.

A newer browser might be nice, but it also would be good if web page
designers built pages with older code in mind.

It _definitely_ has some cool stuff. Thanks, Scott!

--
Comparing Knuth with O'Reilly books is like comparing
Unix with Windows.
-- Abigail, in the Monastery

I have several other browsers, but I prefer using Netscape 4.79. Some
websites are a royal pain. I recently ran into an electronics
distributor who put their entire website in "Flash". There is no way I
will wait five minutes or more per page to download and run stupid
animation when I am looking for parts. I have seen a bunch of sites with
a white background and a very pale yellow text.


My website isn't perfect, but I but a lot of work into making it easy
to use and I asked for, and used, feedback from members of a couple
newsgroups. You can see it at:
http://home.earthlink.net/~mike.terrell/ I still have a lot of work to
do to the site, but a website is never really finished, is it?
--
11 days!


Michael A. Terrell
Central Florida

On Sun, 14 Dec 2003 06:31:14 GMT, "Michael A. Terrell"
wrote:

Some
websites are a royal pain. I recently ran into an electronics
distributor who put their entire website in "Flash". There is no way I
will wait five minutes or more per page to download and run stupid
animation when I am looking for parts.

I share your opinion completelly; I hate Flash made sites & banners,
but not downlodable fun stuff in Flash ... /like jokes/ :-)

-- Regards, SPAJKY
& visit site - http://www.spajky.vze.com
Celly-III OC-ed,"Tualatin on BX-Slot1-MoBo!"
E-mail AntiSpam: remove ##

On Sun, 14 Dec 2003 06:31:14 GMT, "Michael A. Terrell"
wrote:

Some
websites are a royal pain. I recently ran into an electronics
distributor who put their entire website in "Flash". There is no way I
will wait five minutes or more per page to download and run stupid
animation when I am looking for parts.

I share your opinion completelly; I hate Flash made sites & banners,
but not downlodable fun stuff in Flash ... /like jokes/ :-)

-- Regards, SPAJKY
& visit site - http://www.spajky.vze.com
Celly-III OC-ed,"Tualatin on BX-Slot1-MoBo!"
E-mail AntiSpam: remove ##

Mike Andrews wrote:

The Netscape 4.6 browser on
the same system _does_ put the black text directly on the dark-blue
background, and it is decidedly unpleasant.

Mozilla 1.4a doesn't have any problems.

A newer browser might be nice, but it also would be good if web page
designers built pages with older code in mind.

Like trying to accommodate fighting parents, having Micro$oft constantly
extending and subverting standards.

It _definitely_ has some cool stuff. Thanks, Scott!

Thanks. Any things you like more than others? When I make time, I plan
on documenting my tinkering with windows html/hta app to md5 sign and
test your pc files, laser-pointer velocimeter and interferometers, PIC
hardware and software for alarm system, and micro-power radar sensors. I
should update the bookmarks and clean all the dead-links too.

--
Scott

**********************************

DIY Piezo-Gyro, PCB Drill Bot & More Soon!

http://home.comcast.net/~scottxs/

**********************************

Mike Andrews wrote:

On my system (FreeBSD) with the Mozilla FireBird browser, the text
and images are in light-colored windows inside the dark background,
and it's not at all difficult to read. The Netscape 4.6 browser on
the same system _does_ put the black text directly on the dark-blue
background, and it is decidedly unpleasant.

A newer browser might be nice, but it also would be good if web page
designers built pages with older code in mind.

It _definitely_ has some cool stuff. Thanks, Scott!

--
Comparing Knuth with O'Reilly books is like comparing
Unix with Windows.
-- Abigail, in the Monastery

I have several other browsers, but I prefer using Netscape 4.79. Some
websites are a royal pain. I recently ran into an electronics
distributor who put their entire website in "Flash". There is no way I
will wait five minutes or more per page to download and run stupid
animation when I am looking for parts. I have seen a bunch of sites with
a white background and a very pale yellow text.


My website isn't perfect, but I but a lot of work into making it easy
to use and I asked for, and used, feedback from members of a couple
newsgroups. You can see it at:
http://home.earthlink.net/~mike.terrell/ I still have a lot of work to
do to the site, but a website is never really finished, is it?
--
11 days!


Michael A. Terrell
Central Florida