# Spurious measurements FCC

I was wondering if someone can help me with a project at work. I am very very new into RF.

I work for an EMC/EMI lab and we want to do some spurious emissions testing and establish a test procedure for our clients when they have a pre-certified RF module. We want to do a wireless verification (FCC subpart 15 C) ANSI C.10

QUESTION:

I want to make a reasonable and cheap antenna/transmitter that operates at 2.4GHz (Wi-Fi and/or Bluetooth frequencies) duty cycle of 100% or above 98%. It is to mimic a device that has spurious emissions around these frequencies. I do not know what kind of power I need to provide from my signal generator, also how do I ensure that it is continuously transmitting i.e. above 98% duty cycle. I have an idea of the specifications that I want, antenna gain , output power.

We will set our signal generator at a frequency of 2.4GHz and using our Rohde and Schwarz in spectrum analyzer mode will try to measure the spurious emissions and see the duty cycle.

If information is missing I will gladly provide some.

With some calculations I found that the length of the antenna for a half-wave is around 6.22cm and for quarter is 3.11cm. I do not know which one makes more sense.

I am trying to measure the maximum conducted output power I am looking for a device that:

• The transmitter is cable of keeping a constant transmission of data via >98% duty cycle.
• The transmitter has a decent antenna gain around from 3.2 to 4 dBi.
• The transmitter has a decent target output power from 20 to 40 dBm.

Here is an idea of what the setup will look like:

• One hurdle is that many of the cheap WiFi or bluetooth chips don’t tell you much about the low level rf features as they supply a binary blob of code that does all the magic for compliance reasons. The Nordic nrf series do allow lower level control of the rf, so they might be worth a look. As well, some vendors might have special test modes to do what you want. Some research will be needed. Nov 10, 2021 at 21:43
• Im not quite sure what you want to measure, but what about just using a cheap SDR? Nov 10, 2021 at 21:49
• If information is missing ... a question is missing Nov 10, 2021 at 22:43
• The only thing important that is missing is engineer-defined specifications That's your job Nov 10, 2021 at 23:53
• Shouldn't you be able to do that with a Rhode & Schwartz signal generator, tune it to 2.4GHz with required modulation ? If you're looking for an off-the-shelf RF module that one would integrate in another product etc then there are many that may include access to special "test modes" for setting CW carrier and or PRBS modulated continuous carriers as required just for such particular tests that aid with FCC 15C. You'll need to be more specific is it WiFi, Bluetooth, proprietary 2.4GHz ? Nov 11, 2021 at 13:02