Can a Single Probe Accurately Measure RF Power on Multilayered PCBs?

In summary: Spectrum Analyzers to probe RF signal powers at different points on multilayered PCBs. - These probes have a single conductor (or at least only require a single conductor). - Placing the probe on a signal trace on the top exposed surface of the PCBs instantly shows us the RF power at that point. - BUTTTTT How can this be when the RF energy is flowing within the PCB (between two conductors and amongst the DIELECTRIC)? - - It would make sense if we connected one probe on the top conductor and the other probe on the other conductor (usually a ground plane), that way we can multiply a I and V value, but this works on
  • #1
RFbeginner
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I often use Spectrum Analyzers to probe RF signal powers at different points on multilayered PCBs. These probes have a single conductor (or at least only require a single conductor). Placing the probe on a signal trace on the top exposed surface of the PCBs instantly shows us the RF power at that point. BUTTTTT How can this be when the RF energy is flowing within the PCB (between two conductors and amongst the DIELECTRIC)? It would make sense if we connected one probe on the top conductor and the other probe on the other conductor (usually a ground plane), that way we can multiply a I and V value, but this works on 1 probe. They just touch these magic probes on the top layer and BINGO.. they get teh RF POWER reading. How can these devices somehow guide the underlying RF Energy to dive into them
 
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  • #2
I have done a LOT of troubleshooting with a spectrum analyzer. First and foremost, no transmission line whether it be conventional coax or strip-line on a PC board is going to be 100% effective at shielding. Second, how far down on the spectrum is the signal? In other words, what is the signal level sampled? If it is 40 dB down, then the sampled signal is 1/10,000th of the strength of the actual signal. Pretty insignificant.
 
  • #3
How

How does the probe measure the power of the wave that is mostly sandwiched between the layers of dielectric in the PCB? I do realize that a certain % of the energy leaks into the probe, but if that % was not fixed, how do we get proper measurements from the Spectrum Analyzer?
 
  • #4
The analyzer is using Earth ground as a reference, and so is your PCB. Of course, you'd be better off using a differential probe, but it sounds like your single-ended probe gets the job done for you.

- Warren
 

1. What is "RF Probe's magic EM suction"?

"RF Probe's magic EM suction" refers to a type of electromagnetic (EM) probe that is used to detect and measure radio frequency (RF) signals. It is called "magic" because it is able to attract and measure EM waves without physically touching the source.

2. How does "RF Probe's magic EM suction" work?

"RF Probe's magic EM suction" works by using a conductive tip to pick up the electric field of an RF signal. The tip is then connected to a measuring device, such as an oscilloscope, which displays the signal's amplitude and frequency.

3. What types of RF signals can "RF Probe's magic EM suction" detect?

"RF Probe's magic EM suction" can detect a wide range of RF signals, including those used in wireless communication, radar systems, and even microwave ovens. It is also sensitive enough to detect weak signals, making it useful for troubleshooting and testing purposes.

4. Are there any safety concerns when using "RF Probe's magic EM suction"?

Yes, there are safety concerns when using "RF Probe's magic EM suction." As with any electromagnetic device, it is important to follow safety precautions and regulations to avoid exposure to potentially harmful levels of RF radiation. It is also important to use the probe correctly and not touch the tip while it is in use to avoid any potential electric shocks.

5. What are the advantages of using "RF Probe's magic EM suction" over other types of probes?

"RF Probe's magic EM suction" has several advantages over other types of probes. It is non-invasive, meaning it does not physically touch the source of the signal, which can be helpful when working with delicate or sensitive components. It is also highly sensitive and can detect weak signals, making it useful for troubleshooting and testing. Additionally, it is compact and portable, making it easy to use in various settings.

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