• State
  • Locked Locked
  • Replies 3 replies
  • Subscribers 17 subscribers
  • Views 608 views
  • Users 0 members are here
Support feedback
Options
Options
Related

This thread has been locked.

If you have a related question, please click the "Ask a related question" button in the top right corner. The newly created question will be automatically linked to this question.

cc1101 with optinal multiple antenna

Erkan Ersoy
Prodigy 115 points
Other Parts Discussed in Thread: CC1101, CC115L

Hello

My cc1101 application  will be add-on on a gsm application. I am concerned about antenna will be top of another pcb and will make shade antenna. And another problem is orientation. Antenna will probably oriented horizontally to ground (as i understand from radiation patterns antennas doesnt radiate well that direction). My application is 868Mhz. I designed other standalone part with antenna dk #6 antenna. That works well. 


My question is i want to use both pcb antenna and SMA connector like CC110LEM / CC115L 868 - 915 MHz Reference Design (Rev. A) 
I am trying to immitate that design but i am not sure things i am doing.
I will use 50ohm traces for both. In reference design 100pF cap used like jumper (i am not sure if i should use 100pF cap before SMA connector). That there is already filter components for PCB antenna so jumper wont be a problem.

My PCB antenna is inverted F antenna in that reference design: DN023 -- 868 MHz, 915 MHz and 955 MHz Inverted F Antenna (Rev. C)

I have feeling that F antenna will be better for horizontal orientation. 

I am waiting for suggesitons bot for multiple antennas and horizontal oriented antenna

Thank you 


  

  • 0
    TI__Mastermind 36395 points

    Erkan, 

    The most important thing you need to consider is coexistence. The GSM module can output upto 2W of power in the 800/900MHz bands, which is 36dBm. This is 30dB above the maximum rating of the CC1101 and 60dB above any kind of blocking performance. 

    You need to either have a very good filter in front of the CC1101 to protect it from the GSM module OR have some kind of software mechanism that ensures that the GSM module is never on when you expect the CC1101 to work - and even so you need to make sure you are not above the absolute maximum ratings.

    Place the two antenna as far apart on your design as possible.

    Regards,
    /TA 

  • 0 in reply to TA12012
    Prodigy 115 points

    Thank you for answer;

    GSM band in here is 900 Mhz. I am not using channel setup at the moment so i am not going close to 900mhz. I will put antennas as far as possible from gsm antenna.

    I hope no interferrence occures. I tested it with cell phone held very close to it while talking to someone. Seems fine. I will further test it after i finish addon part.

    About my other question. If it is OK if i put 100pF before SMA antenna after 50 ohm trace. Or should i calculate trace impedance with 100pF As i mentioned before i am trying to immitate reference design swrr082a

    Thank you again 

     

  • 0 in reply to Erkan Ersoy
    TI__Mastermind 33630 points

    The 100pF will not effect the measurement so much so this can be disregarded.

    Regards,   Richard.