I need to come
up with a small antenna for a hand-held 40Mhz transmitter. I'd like to
use some sort of rubber duck helicoil to save space if poss.

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

Plug a helical antenna into the output socket.

For 40 MHz, wind 140-150 close-wound turns of enamelled 18 gauge wire on a
0.4-inch diameter plastic or cardboard former. The turns will spread over a
length of about 8 inches.


Whether or not it works will depend on how far away is the receiver.


You can try matching the output impedance by sqeezing the box harder. How
many ohms is your hand + arm + torso + legs to ground?


For helicals of other dimensions download program HELICAL3 from website
below.
----
.................................................. ..........
Regards from Reg, G4FGQ
For Free Radio Design Software go to
http://www.btinternet.com/~g4fgq.regp
.................................................. ..........

Michael wrote:

Hi - I'm using some Laipac "easy link" modules in a custom remote
control/home automation device for my house. I'm using the 433.92mhz
models, datasheet he http://www.laipac.com/Downloads/Easy/TLPRLP434A.pdf
Can anyone give me any advice about how to design an antenna for this?

Checkout:
http://www.rfm.com/corp/appdata/antenna.pdf
too!

--
Scott

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

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

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

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

On Fri, 26 Dec 2003 20:08:07 +0000 (UTC), "Reg Edwards"
wrote:

I need to come
up with a small antenna for a hand-held 40Mhz transmitter. I'd like to
use some sort of rubber duck helicoil to save space if poss.

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

Plug a helical antenna into the output socket.

For 40 MHz, wind 140-150 close-wound turns of enamelled 18 gauge wire on a
0.4-inch diameter plastic or cardboard former. The turns will spread over a
length of about 8 inches.


Whether or not it works will depend on how far away is the receiver.


You can try matching the output impedance by sqeezing the box harder. How
many ohms is your hand + arm + torso + legs to ground?


For helicals of other dimensions download program HELICAL3 from website
below.

Thanks X.05, Reg. What do I use for a ground plane?
--

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

You can try matching the output impedance by sqeezing the box harder. How
many ohms is your hand + arm + torso + legs to ground?


For helicals of other dimensions download program HELICAL3 from website
below.

What do I use for a ground plane?

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

YOU plus the box constitute the groundplane. Otherwise, for example, with a
set of 4 1/4-wave radials you won't be handheld.
---
Reg

On Sat, 27 Dec 2003 07:09:24 +0000 (UTC), "Reg Edwards"
wrote:


You can try matching the output impedance by sqeezing the box harder. How
many ohms is your hand + arm + torso + legs to ground?


For helicals of other dimensions download program HELICAL3 from website
below.

What do I use for a ground plane?

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

YOU plus the box constitute the groundplane. Otherwise, for example, with a
set of 4 1/4-wave radials you won't be handheld.

Thanks Reg! You're a diamond.
--

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

"Paul Burridge" wrote in message
...
On Fri, 26 Dec 2003 13:17:51 +0800, "Rob"
wrote:


"Michael" wrote in message
...
Hi - I'm using some Laipac "easy link" modules in a custom remote
control/home automation device for my house. I'm using the 433.92mhz
models, datasheet he
http://www.laipac.com/Downloads/Easy/TLPRLP434A.pdf
Can anyone give me any advice about how to design an antenna for this?
The
reciever will be embedded in an outside wall - so the antenna can be as
big
as it needs to be. The transmitter's antenna will be in a hand held
device
- so the smaller the better. Can anyone give me any tips as to how to
design this antenna? And sorry for cross posting - I wasn't sure which
of
these two newsgroups this question fit best. Thanks, and happy
holidays!

Michael




There is a directional yagi design @
http://picaxe.orcon.net.nz/yagi433.jpg

Very useful for a hand-held device I *don't* think!
--

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

True! (But I've got big hands.......)
Hopefully it may be of use to others on the NG.