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Antenna tuning with chipset antenna

Hello,

I developed a Nordic board with 2450AT18B100 chipset antenna. I follow the design of Solar Powered Sensor Beacon.

infocenter.nordicsemi.com/index.jsp I test it and it works fine, but I want to tuning the antenna in order to get minimum return lose in signal.

So, I implement this antenna circuit in my board. And

From johanson technology values are: I

I suppose that from C3 and L1 you have to modify some references values of johanson chip antenna.

In general, my questions are:

Can you explain me each part of this circuit?.

Can you explain me why do you change this values and how do you calculated?.

Can you explain me how tuning the antenna?. Because your reference document for that do not explain how to do it in this case.

infocenter.nordicsemi.com/.../nwp_017.pdf

Thanks in advance.

Jose.

Others attached files. Conductor Impedance

image description

Trace Lenght Solar Beacon

image description

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  • Hello Kristin,

    Thanks a lot for your swift reply. I have a new questions...

    How can I measure the output power?.

    About VNA I suppose that the signal of VNA is in C13 and the GND of VNA in L4 (GND), that is right?. About this process...that means that doing that we will be sure about the impedance adaptation between all parts but...what about the frequency resonance?. Imagin that impedance is right but frequency resonance is wrong... I suppose that you make some calculations to do that. Can you shared with us this calculations.

    Thanks in advance.

    Jose.

  • FormerMember
    0 FormerMember in reply to vidal

    Measuring the impedance of the ANT pin on the chip is an alternative way to verify that the output power from the chip is what it should be: When the impedance is (approximately) 50 Ohm across the band, the output power in the 50 Ohm reference point will be the same as what it was set to be. However, measuring the impedance does not, unfortunately, replace the measurement of harmonics. The only way to measure the harmonics is to use a spectrum analyzer. This .pdf explains an important aspect of C3/L1 in terms of suppressing harmonics.

    When using the radio_test example and you want to measure the output power, the signal should be unmodulated. Unmodulated signal is the default. In addition, you would need to set the following settings:

    Constant channel (TX): a, p, c

    Sweep (TX): a, b, p, t

Reply
  • FormerMember
    0 FormerMember in reply to vidal

    Measuring the impedance of the ANT pin on the chip is an alternative way to verify that the output power from the chip is what it should be: When the impedance is (approximately) 50 Ohm across the band, the output power in the 50 Ohm reference point will be the same as what it was set to be. However, measuring the impedance does not, unfortunately, replace the measurement of harmonics. The only way to measure the harmonics is to use a spectrum analyzer. This .pdf explains an important aspect of C3/L1 in terms of suppressing harmonics.

    When using the radio_test example and you want to measure the output power, the signal should be unmodulated. Unmodulated signal is the default. In addition, you would need to set the following settings:

    Constant channel (TX): a, p, c

    Sweep (TX): a, b, p, t

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