Comments on the Reliability of Hand-Held RF Meters

Hand-held RF meters are cost-effective, easy to use, and those with a logarithmic periodic antenna are particularly good at identifying general source-points, such as smart meters, transmitter towers, wifi, cordless phones, BlueTooth, etc. For this reason, hand-held meters serve the excellent work that an Electromagnetic Radiation Specialist, EMRS, would provide you. 

However, please understand that hand-held meters are relatively unreliable for measuring radio signal power levels. The typical hand-held meter is a scalar measuring instrument which will often exaggerate the measured power density levels. Because these meters are not capable of measuring phase, any impedance mismatches and reflections can add in and out of phase distortion with the incident signal you are measuring, resulting in magnitude uncertainty.

Hand-held RF meters are broadband and not frequency selective. All unwanted signals caused by the meter circuitry get averaged into the measurement, causing false readings.

The dynamic range of most power meters is 50 to 70 dB. More expensive professional power meters are capable of specific measurements, such as integrated power across a band and triggering for pulsed RF power. For these reasons, power meters can be the right choice if the RF environment is well controlled. Unfortunately, in New York City, the RF environment is as controlled as the currents in the East River.

Intermodulation resultants are signals generated by nonlinear interactions within the transmitter components. The internal mixer which processes the RF signal has a nonlinear behavior. The mixer outputs the sum and difference of two input signal frequencies, and then the output is isolated. Many meters will have an IF Filter (Intermediary Frequency Filter.) The higher frequency summation is a process known as up-conversion. If the output frequency is higher than the second input frequency, the process is called up-conversion.

The problem with using any mixer within the circuitry path is that mixers can present signal combinations along with their harmonics, as well as leakage of the input signals to the output. The frequency and amplitude of the intermodulation resultants will then change with a delta in the input signals, resulting in yet another way to get an incorrect measurement. In specific environments, care and experience can minimize this effect, but it is near impossible to avoid in a dense RF environment.

We term any unwanted signal as a spurious event or spur. Spurs may occur at any frequency or power level from internal circuitry leakage and external radiative coupling. If you are using an RF meter that costs less than $10,000, then you will be reading spurs for peak readings. We recommend monitoring the RMS (root-mean-squared) readings instead.

The frequent occurrence of false artificial events in hand-held meters is why we only use hand-held RF meters for source-point location, which you can usually do with your own eyes unless you're in a big city. I discourage any professional from using hand-held RF meters for acquiring data to make an accurate assessment of RF signals. At best, use the RMS readings and conduct enough evaluations that you can get a relative awareness of signal strength.

In conclusion, I've measured into the millions of micro-watts per-square-meter only a few times, but have never come close to the FCC guidelines. So, based on what I've written here, please don't buy a meter thinking that you will measure levels exceeding the FCC recommendations, especially a hand-held RF meter. And, please don't call Elexana if you want us to measure a nearby cell tower so you can initiate a lawsuit based on RF levels. It's a waste of our time and your money. If you don't believe me, just read Bill Clinton's Telecom Act of 1996 and Barack Obama's 2012 and 2014 addendums. You will not win any lawsuit suing a telecom or a building management company hosting a cell tower unless the laws change.