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IWR1642: What are limitations on custom antenna design?

Herman Stubeda
Intellectual 290 points
Part Number: IWR1642
Other Parts Discussed in Thread: AWR1243

Hello, 

I am working with the BOOST board at the moment, and I am also considering the design of a custom breakout board for the IWR1642 IC. So I am wondering about any limiting parameters and properties on the antenna design. 

I have read in another post that impedance matching of 50Ohms is optimal. Is this for a single antenna trace? Of for each set of TX and RX antennae?

Given this impedance limit, can you recommend any tips about antenna shape. For example, what was the reason behind designing the antennae having square nodes on the BOOST board. Does larger surface area increase gain? And how to determine optimal antenna shape?

Lastly, I was wondering if you can see any issue with having the antenna lines to be insulated wires of about 40cm. If the impedance can be matched to 50Ohms, then what other factors in such a long wire can affect signal gain? Maybe you guys already have experience in testing longer antennas. Will EMI be significant?

Thank you

  • 0
    Expert 1985 points

    Hi Herman,

    There are many hints in antenna design, especially the UWB and mmWave frequency antenna, this type of antenna known by the following names:
    "series-fed patch array antenna"
    There are many parameters that include antenna design and control of certain conditions is not easy:
    Gain/VSWR/Impedance/BandWidth and … .
    One of the main sources of antenna design is:
    Title: Antenna Theory: Analysis and Design
    Author(s): Constantine A. Balanis
    www.wiley.com/.../productCd-1118642066.html

    Regards,
    Amin

  • 0
    TI__Mastermind 37500 points

    Hello

    The IWR1642 antenna is based on the AWR1243 initial antenna with 4 Rx active elements, and 2 Tx elements.   The 50 ohms is required for matching the RF Tx1, Tx2, Rx1, Rx2, Rx3, and Rx4 connections.

    The antenna design is based on the desired center frequency, chirp band, desired gain, and for the multi-element patch the field of view.  The "square nodes" are a patch antenna.   Here is a paper describing patch antenna design, publications.lib.chalmers.se/.../235807.pdf

    The Rogers 4835 LoPro RF material on Layer 1 of the EVM, has specific transfer properties that are ideal for RF transmission.    Insulated wires don't have this transmission and reflectance property.   If you are modifying the EVM to connect to an external antenna, you should connect Coaxial cable with the proper RF properties, you will also have non optimal S parameters, which will degrade the signals.

    Insulated wire connection is not recommended.

    We do not solder on external antennas.  If you wanted to redesign the EVM, there are 1mm RF connectors that would replace the patch antenna, we do not have that board available.

    Regards,

    Joe Quintal