BLE antenna design

MUHAMMAD FAIZZUDDIN BIN RAZALI

Other Parts Discussed in Thread: CC2540

Hi,

I have a question regarding antenna design of CC2540 USB dongle. With this I attach a picture of antenna design. My concerning is :

1) If the connection are connected to ground, would it be interfered to the whole RF transmission of the antenna? ( Refer question 1)

2) If I want to redesign the antenna, can I remove the portion as in attachment? (Refer question 2) Would it be changing for antenna radiation and so forth?

Please assist, and explanation with graphical method will be helpful.

Thank you.

over 10 years ago

0 Fredrik K over 10 years ago

TI__Guru** 106705 points

Hi Muhammad,

All dimensions of the antenna are carefully selected so the antenna will work properly. You should not change any aspects of it if you want your RF performance to be good.

You can google "inverted F antenna" to learn why the right part must be connected to ground.

Cheers,
Fredrik

0 MUHAMMAD FAIZZUDDIN BIN RAZALI over 10 years ago in reply to Fredrik K

Prodigy 20 points

Hi Fredrik K,

Thanks for the assistance. But is there any particular reasons why I can't modify the design? I might get a different results from my radiation pattern and so on, am I right?

Thanks again.

0 Fredrik K over 10 years ago in reply to MUHAMMAD FAIZZUDDIN BIN RAZALI

TI__Guru** 106705 points

Hi Muhammad,

If you remove the right part of the antenna it will not work at all. It is a key part of an inverted-F antenna to ensure right resonance frequency. Again, I would recommend reading up on the topic as antenna design is very complex.

Cheers,
Fredrik

0 kazola over 10 years ago in reply to MUHAMMAD FAIZZUDDIN BIN RAZALI

Guru 18625 points

Hi MUHAMMAD FAIZZUDDIN BIN RAZALI

that part of the antenna has to be connected to ground. For you to understand, if that part is not connected to ground, it will not work at 2.4 GHz (Bluetooth frequency) but probably about... 4 GHz? This is just a wild guess, but it will not work :) Then you will have no range at all. For the same reason, do not cut any other part of the antenna without knowing what you are doing.

If you are in a hurry, the following link will explain lots of things to you, and even it contains an example for BLE antenna development.
www.antune.net/.../index.html

Have a nice day!

0 Robert Chen over 10 years ago

Mastermind 9135 points

For antenna, you have to view the signal running on "PCB trace" in microwave way. You may think the portion connected to GND will make it shorted, but in microwave domain, a trace in strange shape could act as a resistor, a capacitor, an inductor or a filter.

The design of antenna requires good knowledge of microwave theory and practice.

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