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

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

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

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

"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

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