Potted 900MHz PCB antenna
 

Hi,

I have an interesting project! I am using a RF receiver device which has a
50 Ohm RF input. I want to use a PCB printed antenna on FR4 board, not
unusual you say. but I need to pot the whole PCB in resin to make it
waterproof. The receiver only needs to work when floating on water! Has
anyone any experience in PCB antenna who would be so kind to comment on the
effects, and possible actions to counter any effects, of the potting. The
resin is much like araldite.



Any thoughts much appreciated.



Will

On Tue, 14 Oct 2003 18:27:50 +0000 (UTC), "Will Reeve"
wrote:

Hi,

I have an interesting project! I am using a RF receiver device which has a
50 Ohm RF input. I want to use a PCB printed antenna on FR4 board, not
unusual you say. but I need to pot the whole PCB in resin to make it
waterproof. The receiver only needs to work when floating on water! Has
anyone any experience in PCB antenna who would be so kind to comment on the
effects, and possible actions to counter any effects, of the potting. The
resin is much like araldite.



Any thoughts much appreciated.



Will


Hi Will,

Look into conformal coating as an alternative. Or simply mix acetone
and RTV to create one and paint it on. To cut down on water losses,
it would do well to provide an air jacket around the antenna elements
that is roughly a tenth wavelength in diameter (and from the tips).

73's
Richard Clark, KB7QHC

Will Reeve wrote:
Hi,

I have an interesting project! I am using a RF receiver device which has a
50 Ohm RF input. I want to use a PCB printed antenna on FR4 board, not
unusual you say. but I need to pot the whole PCB in resin to make it
waterproof. The receiver only needs to work when floating on water! Has
anyone any experience in PCB antenna who would be so kind to comment on the
effects, and possible actions to counter any effects, of the potting. The
resin is much like araldite.



Any thoughts much appreciated.



Will




The potting compound will act as a dielectric load. My bet is that the
dielectric constant will be about 3. Your antenna will have to shrink.
If you know the dielectric properties of the potting compound, and
your antenna is simple, then I might be able to run a simulation (and
optimization) for you with IE3D.... I work with 900 MHz antennas on FR4
every day :)

Wayne Shanks
Senior RF and Antenna Engineer, Matrics Inc.

If the antenna is in close proximity to water, the water's dielectric
constant of about 80 will have a profound effect, as will its very high
loss.

Roy Lewallen, W7EL

Wayne Shanks wrote:
Will Reeve wrote:

Hi,

I have an interesting project! I am using a RF receiver device which
has a
50 Ohm RF input. I want to use a PCB printed antenna on FR4 board, not
unusual you say. but I need to pot the whole PCB in resin to make it
waterproof. The receiver only needs to work when floating on water! Has
anyone any experience in PCB antenna who would be so kind to comment
on the
effects, and possible actions to counter any effects, of the potting. The
resin is much like araldite.



Any thoughts much appreciated.



Will




The potting compound will act as a dielectric load. My bet is that the
dielectric constant will be about 3. Your antenna will have to shrink.
If you know the dielectric properties of the potting compound, and your
antenna is simple, then I might be able to run a simulation (and
optimization) for you with IE3D.... I work with 900 MHz antennas on FR4
every day :)

Wayne Shanks
Senior RF and Antenna Engineer, Matrics Inc.

www.fwt.niat.net

This dielectric embedded antennas are smaller than naturally occurs and yet
have a net gain


"Roy Lewallen" wrote in message
...
If the antenna is in close proximity to water, the water's dielectric
constant of about 80 will have a profound effect, as will its very high
loss.

Roy Lewallen, W7EL

Wayne Shanks wrote:
Will Reeve wrote:

Hi,

I have an interesting project! I am using a RF receiver device which
has a
50 Ohm RF input. I want to use a PCB printed antenna on FR4 board, not
unusual you say. but I need to pot the whole PCB in resin to make it
waterproof. The receiver only needs to work when floating on water! Has
anyone any experience in PCB antenna who would be so kind to comment
on the
effects, and possible actions to counter any effects, of the potting.
The
resin is much like araldite.



Any thoughts much appreciated.



Will




The potting compound will act as a dielectric load. My bet is that the
dielectric constant will be about 3. Your antenna will have to shrink.
If you know the dielectric properties of the potting compound, and your
antenna is simple, then I might be able to run a simulation (and
optimization) for you with IE3D.... I work with 900 MHz antennas on FR4
every day :)

Wayne Shanks
Senior RF and Antenna Engineer, Matrics Inc.

On Mon, 03 Nov 2003 17:00:58 GMT, "Marc H.Popek"
wrote:

www.fwt.niat.net

This dielectric embedded antennas are smaller than naturally occurs and yet
have a net gain

Hi Marc,

Interesting sentence construction.

A cogent question would reveal some perspective: How much would your
13dBi dielectric embedded antennas for TV Channel 2 weigh?

73's
Richard Clark, KB7QHC

"Marc H.Popek" wrote in message
...
www.fwt.niat.net

This dielectric embedded antennas are smaller than naturally occurs and
yet
have a net gain

More correctly, they CLAIM a gain, relative to isotropic.

If the antenna is smaller than a free space antenna, then it looses capture
area.
I would be very interested to know how they recoup that.
I suspect these antennas might need some power to drive an on-board
amplifier, which means that their gain claim is bogus, and what they aren't
telling you is that the noise floor comes up also.

TANSTAAFL.

On Mon, 3 Nov 2003 16:40:59 -0500, "Dave VanHorn"
wrote:


"Marc H.Popek" wrote in message
...
www.fwt.niat.net

This dielectric embedded antennas are smaller than naturally occurs and
yet
have a net gain

More correctly, they CLAIM a gain, relative to isotropic.

They? HE (the CTO in fact). American business has a recent history
of clown elevation.


If the antenna is smaller than a free space antenna, then it looses capture
area.

Capture area is hardly an issue for even the full size antennas they
replace.

I would be very interested to know how they recoup that.
I suspect these antennas might need some power to drive an on-board
amplifier, which means that their gain claim is bogus, and what they aren't
telling you is that the noise floor comes up also.

TANSTAAFL.

Hi Dave,

What is more to the matter is unstated issues of efficiency. I will
let the claims of 8 fold boons pass (which is marketese from the world
of ENRON). Compare these "advantages" of reclaimed volume to the
unanswered query of weight (no claims about density are there?).

Leftover halloween candy.

73's
Richard Clark, KB7QHC

Richard Clark wrote:

On Mon, 03 Nov 2003 17:00:58 GMT, "Marc H.Popek"
wrote:

www.fwt.niat.net

This dielectric embedded antennas are smaller than naturally occurs and yet
have a net gain

Hi Marc,

Interesting sentence construction.

A cogent question would reveal some perspective: How much would your
13dBi dielectric embedded antennas for TV Channel 2 weigh?

73's
Richard Clark, KB7QHC

A lot less than they would for the 160 meter ham band.

--
Many thanks,

Don Lancaster
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
voice: (928)428-4073 email: fax 847-574-1462

Please visit my GURU's LAIR web site at http://www.tinaja.com

Funnily enough, there is no decrease in capture area with simple, very small
antennas. This is a difficult conception to get people's brains around.

There is only a (but important) decrease in efficiency because radiation
resistance decreases faster than the loss resistances incurred in matching
the antenna to the receiver. Matching loss resistance increases as the
antenna dimensions become smaller.

For example, think in terms of the Q and loss resistance of the high
inductance coil needed in an antenna tuner.

On Mon, 03 Nov 2003 16:54:59 -0700, Don Lancaster
wrote:

Richard Clark wrote:

On Mon, 03 Nov 2003 17:00:58 GMT, "Marc H.Popek"
wrote:

www.fwt.niat.net

This dielectric embedded antennas are smaller than naturally occurs and yet
have a net gain

Hi Marc,

Interesting sentence construction.

A cogent question would reveal some perspective: How much would your
13dBi dielectric embedded antennas for TV Channel 2 weigh?

73's
Richard Clark, KB7QHC

A lot less than they would for the 160 meter ham band.

--
Many thanks,

Don Lancaster
Synergetics 3860 West First Street Box 809 Thatcher, AZ 85552
voice: (928)428-4073 email: fax 847-574-1462

Please visit my GURU's LAIR web site at http://www.tinaja.com

Hi All, Don,

I would least of all think that "Many thanks" was aimed specifically
at me for such little contribution as I've offered; that aside, for
those in the rec.radio.amateur.antenna group, I would offer that Don
is one of the more "out of the box" technical thinkers (sorry for the
strained expression) and I would suggest they follow the link he
offers.

As I have been a subscriber to Circuit Cellar since its inception,
I've found Don's articles (and books before then) contained unique
solutions to problems that have defied conventional analysis. Or
rather those problems that have defied clear analysis through other's
falling back on conventional and spontaneously dead answers.

73's
Richard Clark, KB7QHC

Sir Clark,

No work on using the embedded moldable plastic dielectric at 50 Mc... as you
point out the size and weight does not appear to be advantageous.

However, above 900 the size shrink, has an advantage

we have other ideas to use the FWT at lower frequencies.... stay tuned

"Richard Clark" wrote in message
...
On Mon, 03 Nov 2003 17:00:58 GMT, "Marc H.Popek"
wrote:

www.fwt.niat.net

This dielectric embedded antennas are smaller than naturally occurs and
yet
have a net gain

Hi Marc,

Interesting sentence construction.

A cogent question would reveal some perspective: How much would your
13dBi dielectric embedded antennas for TV Channel 2 weigh?

73's
Richard Clark, KB7QHC

You need to understand more about capture area effective area etc.

The Bogus gain is relatively easy to measure, open field, sig generator two
standard dipoles and then compare with the FWT OR

two FWT's antennas on same range and use Friis equation to predict expected
isotropic, then you compare with what your DUT performs ...

It really has the gain we claim, sir!




"Dave VanHorn" wrote in message
...

"Marc H.Popek" wrote in message
...
www.fwt.niat.net

This dielectric embedded antennas are smaller than naturally occurs and
yet
have a net gain

More correctly, they CLAIM a gain, relative to isotropic.

If the antenna is smaller than a free space antenna, then it looses
capture
area.
I would be very interested to know how they recoup that.
I suspect these antennas might need some power to drive an on-board
amplifier, which means that their gain claim is bogus, and what they
aren't
telling you is that the noise floor comes up also.

TANSTAAFL.

the standard antenna's on the web site, have a weight that span from 1 oz
to 4 oz for the smallest to biggest, respectively.

1/2 the linear dimension = 1/8 volume if Enron's finances were this
rudimentary, they would still be in business!

Hey consider this,

an antenna with 1/4 the aspect ratio (effective front viewed area) also has
a 1/4 chance of being hit by a defined shrapnel density specified in
military antenna requirements. AS FWT ARE smaller, they also posses a lower
probability of damage from gunfire for a given field.



"Richard Clark" wrote in message
...
On Mon, 3 Nov 2003 16:40:59 -0500, "Dave VanHorn"
wrote:


"Marc H.Popek" wrote in message
...
www.fwt.niat.net

This dielectric embedded antennas are smaller than naturally occurs and
yet
have a net gain

More correctly, they CLAIM a gain, relative to isotropic.

They? HE (the CTO in fact). American business has a recent history
of clown elevation.


If the antenna is smaller than a free space antenna, then it looses
capture
area.

Capture area is hardly an issue for even the full size antennas they
replace.

I would be very interested to know how they recoup that.
I suspect these antennas might need some power to drive an on-board
amplifier, which means that their gain claim is bogus, and what they
aren't
telling you is that the noise floor comes up also.

TANSTAAFL.

Hi Dave,

What is more to the matter is unstated issues of efficiency. I will
let the claims of 8 fold boons pass (which is marketese from the world
of ENRON). Compare these "advantages" of reclaimed volume to the
unanswered query of weight (no claims about density are there?).

Leftover halloween candy.

73's
Richard Clark, KB7QHC

Exactly, plus consider this,

the raditiative elements, are operating at 1/4 resonances (hence preferable
radiation resistance and bandwidths too!) it just that they are smaller in a
dielectric than in free space. further, the spacing between array elements,
directors, reflectors, etc also shrink by the Er ^0.5. shrinking the
aggregate spacing and the overall dimensions of the final antenna.

Stayed tuned as we are releasing bi & tri band antenna's soon.

And a host of UWB antennas. Even a UWB optimized to deposit energy inside
of a human for echocardio-graphic imaging has UWB radar... UWB antenna
technology is in need of standard product offerings... needs better sign
generation too!

I'd like to see the electronics for wi fi and uwb put onto or into the
antenna FWET antenna modules, simplifying the critical electronics to
antenna interface.


"Reg Edwards" wrote in message
...
Funnily enough, there is no decrease in capture area with simple, very
small
antennas. This is a difficult conception to get people's brains around.

There is only a (but important) decrease in efficiency because radiation
resistance decreases faster than the loss resistances incurred in matching
the antenna to the receiver. Matching loss resistance increases as the
antenna dimensions become smaller.

For example, think in terms of the Q and loss resistance of the high
inductance coil needed in an antenna tuner.

"Marc H.Popek" wrote in message
...
You need to understand more about capture area effective area etc.

The Bogus gain is relatively easy to measure, open field, sig generator
two
standard dipoles and then compare with the FWT OR

two FWT's antennas on same range and use Friis equation to predict
expected
isotropic, then you compare with what your DUT performs ...

It really has the gain we claim, sir!

As it happens, I'm headed to DLS in chicago soon http://www.dlsemc.com/ ,
and I have an application for this sort of antenna, provided it passes the
"snake oil" test. www.mobilecommand.net

We have a bluetooth module that could use such an antenna, as well as a
wi-fi module coming along in the near future.

If I can wedge it into our testing day, I wouldn't mind giving it a test,
and reporting the results back here.

On Wed, 05 Nov 2003 16:17:14 GMT, "Marc H.Popek"
wrote:

Sir Clark,

No work on using the embedded moldable plastic dielectric at 50 Mc... as you
point out the size and weight does not appear to be advantageous.

However, above 900 the size shrink, has an advantage

we have other ideas to use the FWT at lower frequencies.... stay tuned


CTO?

What does that stand for in your organization?

If we are to judge your product (which, by the way, has a page down):
Standard Features
...
* Specifications - FWT Antennas can be built from 49 to 10,000 MHz.

Seems you could have as easily claimed
* Specifications - FWT Antennas can be built from 900 to 10,000 MHz.
if, in fact, that could be achieved.

73's
Richard Clark, KB7QHC

On Wed, 05 Nov 2003 16:30:51 GMT, in rec.radio.amateur.antenna you
wrote:

the standard antenna's on the web site, have a weight that span from 1 oz
to 4 oz for the smallest to biggest, respectively.

1/2 the linear dimension = 1/8 volume if Enron's finances were this
rudimentary, they would still be in business!

Hey consider this,

an antenna with 1/4 the aspect ratio (effective front viewed area) also has
a 1/4 chance of being hit by a defined shrapnel density specified in
military antenna requirements. AS FWT ARE smaller, they also posses a lower
probability of damage from gunfire for a given field.


CTO,

1 to 4 Oz at what scale and to what comparison? More ENRON marketing
factoids. ENRON has no product offered and I notice you have no page
of products offered either.

Would you like to comment on how much flak your virtual designs have
avoided here? It would seem you have the boy scout's electronics
dictionary handy to draw terms from indiscriminately to scatter
through these non-responsive marketing postings you are making (from
your home computer? :-)

Sales must be extremely tenuous for you to have to find ego-salve in
an amateur group. Let's see, a slow server, a .net domain name,
posting business news from a private account, no products, but a lot
of power-point presentations and you have trouble with the fundamental
questions. All of this adds up to a vanity web site.

Let's look at another factoid published:
Marc Popek, CTO of Focused Wave Technology Group,
moved to Las Vegas over sixteen years ago.
He is a successful entrepreneur and American inventor,
holding over 12 patents in a wide swath of technologies;
including laser control, exotic signal processing,
intelligent controls, wireless communications and antennas.

Through a search of the PTO against the name Popek we find:
Results of Search in 1976 to present db for:
IN/Popek: 27 patents

9 Popek; Marc H. (Las Vegas, NV)
Apparatus and method for automatic climate control- filed 1994
Phased array acoustic signal processor - filed 1988
Impulse waveform drive apparatus for surface acoustic wave chirp
system - filed 1988
Process for fabricating a sculptured stripling interface conductor
- filed 1988
Electro-optical phase modulator - filed 1988
Sculptured stripline interface conductor - filed 1986
Driver unit for a laser Q-switch - filed 1985
Linear gain voltage controlled oscillator with modulation
compensation - filed 1983
Frequency modulation system for a frequency synthesizer
- filed 1984
7 Popek; Bruce P. (South Windsor, CT)
3 Popek; Witold J. (716 S. Milwaukee Ave., Wheeling, IL 60090)
2 Karen Popek (Poughquag, NY)
2 Popek; Joseph C. (Detroit, MI)
2 Popek; Gerald J. (Los Angeles, CA)
2 Popek; Stephen (Warren, OH)

How does this compare with:
holding over 12 patents in a wide swath of technologies;
12? I count 9. Wide technologies? The majority during the late 80's
were assigned to Harris, earlier work to Motorola. The titles above
reveal those were typically confined to one very specialized segment.

including laser control, exotic signal processing,
intelligent controls, wireless communications and antennas.
The only antennas patented, by Bruce, not Mark, were for toys.
Intelligent controls? HVAC comes to mind for work 10 years ago.
Laser control and signal processing are not simple topics, but neither
are they applicable to antennas barring unique invention - notably
absent from the list above.

Is this talent fungible to antennas commonly courted in this group?
Could be, but there is clearly an absence in experience to the matter
insofar as the grandiose credentials suggest.

The fact of the matter is that the material presented at:
http://www.fwt.niat.net/
is not much more than antenna engineering samples drawn from classroom
introductory lab work at the local University.

73's
Richard Clark, KB7QHC