Patch antena 2.45 ghz radiation pattern problem

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ee98172

Joined: 05 Mar 2008
Posts: 7

25 May 2009 14:33 Patch antena 2.45 ghz radiation pattern problem

I'm testing a patch antena 2,45ghz with HFSS v10 and the radiation pattern is very different form the datasheet from it.
Can anyone see in the file were is the problem?

result from simulation:

datasheet:

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rotmanlens

Joined: 13 Feb 2008
Posts: 52
Helped: 3

26 May 2009 4:05 Re: Patch antena 2.45 ghz radiation pattern problem

i will check it out for you tommorow when i go to school regards
sajid mohammed.

ee98172

Joined: 05 Mar 2008
Posts: 7

27 May 2009 16:48 Re: Patch antena 2.45 ghz radiation pattern problem

Thanks

If you find some problem please tell me?

rotmanlens

Joined: 13 Feb 2008
Posts: 52
Helped: 3

27 May 2009 19:28 Re: Patch antena 2.45 ghz radiation pattern problem

brother i couldnt understand the transition u were making from 50 ohms to the patch input imperdance which i have calculateed to be equal to 91 ohms. and more over the transition u have used is more than quarter of a lambda from the 50 ohm line.so i am assuming that could be the reason for a 90 degree phase shift difference between your results and the standard ones.the transition is 7.1 mm longer than a quarter wave.and the width of the line at the patch is not close to 91 ohms at all it seems way higher than it is.

and i am working on your design .i will let u know as soon as i am done.

regards
sajid mohammed.

Added after 55 minutes:

Bro.here is a patch i have simulated and the problem seems to be the length of the transformer you have used.i have used a quarter wave transformer.i dint spend a min on gain.since the problem was with the pattern orientation and since i have lot of work here i concluded your work while my simualtions were running but if u want and have time.i can look at the gain too.i am attaching a file each of hfss and designer.my HFSS is 11 so i dont know if it works for yours or not.if it solves your problem i would be happy to know so Smile

.

regards
sajid mohammed.

(2:77) Do they not know, then, that --- is aware of all that they would conceal as well as of all that they bring into the open?

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ee98172

Joined: 05 Mar 2008
Posts: 7

28 May 2009 3:36 Re: Patch antena 2.45 ghz radiation pattern problem

By my calculation

Rr=304.4 ohm so the adaptation must be Z=123 ohm

For the 50 ohm line the dimension is W=3mm L=12.196mm

and for the adaptaion is W=0.348mm and L=18mm

is this a problem whid this values

rotmanlens

Joined: 13 Feb 2008
Posts: 52
Helped: 3

28 May 2009 3:43 Re: Patch antena 2.45 ghz radiation pattern problem

of course there is a serious problem with those values of your quarter wave transformer.look at the values of mine they have been cross checked coupal times

regards
sajid mohammed.

ee98172

Joined: 05 Mar 2008
Posts: 7

28 May 2009 4:10 Re: Patch antena 2.45 ghz radiation pattern problem

It's strange. the value for the lambda/4 W was given to me from a datashet of this antenna.

Question: the L of the 50ohm line and de lambda/4 is not very relevant?

rotmanlens

Joined: 13 Feb 2008
Posts: 52
Helped: 3

28 May 2009 4:12 Re: Patch antena 2.45 ghz radiation pattern problem

the length of quarter wave is very important but not the 50 ohm line.and the way you drew your quarter wave was something new.

regards
sajid mohammed.

ee98172

Joined: 05 Mar 2008
Posts: 7

28 May 2009 4:24 Re: Patch antena 2.45 ghz radiation pattern problem

i'm building this antenna from a pdf and the only values that i have is, the dimension of the substrate, antena, W of the quarter wave transformer, and the Rr=304,4 ohm.

From this i was trying to simulate in HFSS v10

Added after 3 minutes:

What is the formula for the quarter wavelenght trasnformer?

Added after 39 seconds:

i'm using this site

http://www.emtalk.com/mscalc.php

rotmanlens

Joined: 13 Feb 2008
Posts: 52
Helped: 3

28 May 2009 5:13 Re: Patch antena 2.45 ghz radiation pattern problem

sure the length of quarter wave transformer is sqrt(ZO*Zc) where Zo is the 50 ohm Zc is the characterisitic impedance of the antenna.and if u are using the calculator of that website then it doesnt give you the proper impedance.

regards
sajid mohammed.

ee98172

Joined: 05 Mar 2008
Posts: 7

28 May 2009 15:11 Re: Patch antena 2.45 ghz radiation pattern problem

Thanks.

And the formula for de W and L of the quarter wave transformer.

rotmanlens

Joined: 13 Feb 2008
Posts: 52
Helped: 3

28 May 2009 16:37 Re: Patch antena 2.45 ghz radiation pattern problem

actually there is a whole bunch of formulas to calculate it .so i have made a mathcad file of it to calculate the L and W of the transformer.and also desinger has a option for calculating them.

regards
sajid mohammed.