Searching \ for '...RF modules and antenna problems' in subject line. ()
Make payments with PayPal - it's fast, free and secure! Help us get a faster server
FAQ page: www.piclist.com/techref/index.htm?key=modules+antenna
Search entire site for: '...RF modules and antenna problems'.

Truncated match.
PICList Thread
'...RF modules and antenna problems'
1998\12\04@073224 by Seyler, Jean-Yves

flavicon
face
 Re-hello Jochen,

I will "comment" would you said :
-------------
a small patch of PCB, about 2*2 cm will be sufficient if the antenna is
designed on the PCB as part of the layout. The centre of the spiral can be
connected on the otherb conductor side of the PCB, but only a small line,
NOT a groundplane (This would help your problem all right, because ALL
transmitting would be next to Zero...).

Alternately, you can try a small cylindrical coil of standard enameled
copper wire. This coil can bhe so placed that the magnetic field will cause
less interference in one preferred direction... you have to experiment with
the size, about 3mm diameter and 10 loops will do the trick if range is not
paramount.

Feel free to comment...

Jochen DH6FAZ
spam_OUTjfTakeThisOuTspamdetektor.de
----------------
For me, it is hard to add the patch (2x2 cm) since I lack drasticaly of
place inside by box (I have the 12v cell, a switch, the coder, the hybrid Tx
... -> So, I will have to try the "cylindric coil" (I already thought of it).
I thought of a coil with a wire length equivalent to the lambda / 4 i.e 18 cm
(at 433 MHz), that would rather drive to more than 10 loops on a 3mm diameter
...
My other inquiry is about the connexion of the antenna / coil :
do I have to ground the other side of it ? I have seen those designs but a
wonder : with a lambda / 4, the other side is at a max of the wave, so not to
be grounded ... that should only be done with wave minimum at the end (lambda
/ 2) ...
Do I make a mistake in my thinking ?
Any comment ?
Thanks

P.S.: My aim is only some meters (<10) with a 12v supply ...

_______________________________________________________
Jean-Yves SEYLER Opto-Electronics Department - BPi 2101
Phone : 33+ (0)5.61.28.18.52 FAX : 33+ (0)5.61.28.18.15
E-mail: .....Jean-Yves.SeylerKILLspamspam@spam@cnes.fr
__  __   __   __
/   |  \ /__\ |__    CNES : French Space Agency
\__ |  | \__   __|   Centre Spatial de Toulouse
                                  \\\\\////
CNES - 18, Avenue Edouard Belin    / ^   - \
31401 TOULOUSE CEDEX (FRANCE)     ( (o) (o) )
_____________________________oOOO_____(_)_____OOOo_____

1998\12\04@080306 by Jochen Feldhaar

flavicon
face
Hello Jean-Yves,

your thinking is partially right! The length of the wire is important if
you are indeed using a quarter-lambda antenna as a straight wire...
The coil will work as an inductive load, and the wire length that is used
for winding it is not in any way correlated to the lambda-quarter length.
Of course, the antenna is not as efficient as a straight wire...
But I reckon this is a simple design, you should experiment a little with
the size and diameter. Anyway, the other end will have to be connected to
ground! Otherwise, the coil of such small dimensions would just be a
capacitor of about 1 pF against the air, and not usable at all. I'm sorry I
forgot to tell you this!

Have fun...

Jochen DH6FAZ

1998\12\04@142009 by William Chops Westfield

face picon face
IIRC, the Lynx technologies web site (another rf module supplier) has some
nice ap-notes on antenna design...

BillW

1998\12\05@084021 by Peter L. Peres

picon face
On Fri, 4 Dec 1998, Jochen Feldhaar wrote:

> But I reckon this is a simple design, you should experiment a little with
> the size and diameter. Anyway, the other end will have to be connected to
> ground! Otherwise, the coil of such small dimensions would just be a
> capacitor of about 1 pF against the air, and not usable at all. I'm sorry I
> forgot to tell you this!

You mean of course, a wide-pitched 3 mm coil, yes ? i.e. the pitch is much
larger than the wire diameter (about 3 to 4 times larger if I'm not wrong)
? Do you tune the coil by compressing/pulling it or do you just let it be
?

thanks,

Peter

1998\12\07@040145 by Seyler, Jean-Yves

flavicon
face
 Hi Bill,

Where could I find theese ap-notes ?

Thanks

----------
De :  William Chops Westfield[SMTP:billwspamKILLspamcisco.com]
Date : vendredi 4 dŽcembre 1998 20:10
A : pic microcontroller discussion
Cc : Seyler Jean-Yves
Objet : Re: ...RF modules and antenna problems

IIRC, the Lynx technologies web site (another rf module supplier) has some
nice ap-notes on antenna design...

BillW

1998\12\07@051730 by Jochen Feldhaar

flavicon
face
OOPS!

I have made a glitch somewhere in my language...
The coil in question is about 8 mm long with its 10 loops and 3 mm
diameter, so the space between adjacent loops is very narrow...
The objective is to get the magnetic field lines to go through the "hole"
as in a solenoid. Of course, the efficiency of such an antenna is limited,
but if you have several milliwatts and only want to cover some meters, then
it will be OK.

Sorry 'bout the glitch.

Jochen DH6FAZ

1998\12\07@053430 by Seyler, Jean-Yves

flavicon
face
So the diameter of the wire is more or less :
8 mm / 10 = 8/10 mm  ;-)

and I also guess that the "3mm diameter for the coil" is the outside diameter
...

Right ?
Bye

J-Yves
----------
De :  Jochen Feldhaar[SMTP:.....jfeldhaaKILLspamspam.....DETEKTOR.DE]
Date : lundi 7 dŽcembre 1998 11:09
A : pic microcontroller discussion
Cc : Seyler Jean-Yves
Objet : Re: ...RF modules and antenna problems

OOPS!

I have made a glitch somewhere in my language...
The coil in question is about 8 mm long with its 10 loops and 3 mm
diameter, so the space between adjacent loops is very narrow...
The objective is to get the magnetic field lines to go through the "hole"
as in a solenoid. Of course, the efficiency of such an antenna is limited,
but if you have several milliwatts and only want to cover some meters, then
it will be OK.

Sorry 'bout the glitch.

Jochen DH6FAZ

1998\12\07@053642 by Stephane Favard

flavicon
face
> OOPS!
>
> I have made a glitch somewhere in my language...
> The coil in question is about 8 mm long with its 10 loops and 3 mm
> diameter, so the space between adjacent loops is very narrow...
> The objective is to get the magnetic field lines to go through the "hole"
> as in a solenoid. Of course, the efficiency of such an antenna is limited,
> but if you have several milliwatts and only want to cover some meters, then
> it will be OK.
>
> Sorry 'bout the glitch.
>
> Jochen DH6FA

This antenna is for 433Mhz 1/4 wave ???

More... (looser matching)
- Last day of these posts
- In 1998 , 1999 only
- Today
- New search...