I think you may mean dBm or dBmW here. 0dBm == 1mW.
The SI symbol for Watt is ‘W’ not ‘w’.
At 2.4GHz, free space path loss is -41dB at 1m, so even a 20dBm radio and a 20dBi directional antenna (and assuming 0dB of insertion loss), the signal strength at 1m is -1dBm, or about 0.79 mW.
At 3m, the free space path loss is nearly -50dB. Now the signal from the setup above is at -10dBm, or 0.1mW.
https://ecfsapi.fcc.gov/file/10417871820142/2018%2BRF%2BRadi...
Maybe rats skull size is perfectly resonant at that frequency, who knows.
resonance seems plausible
Consumer ovens work around a nominal 2.45 gigahertz (GHz)—a wavelength of 12.2 centimetres (4.80 in) in the 2.4 GHz to 2.5 GHz ISM band
And as they correctly point out, that consumer ovens use a specific frequency has nothing to do with it being a resonance frequency of water, but it being a reasonable to use and legal frequency to do so. They would work on 1 GHz or 5 GHz too.
The parent wasn't speaking about "the part of the electromagnetic spectrum we call microwaves" in general, but about what's "used in microwaves to heat our food", i.e. microwave ovens.
Check my submission history for my creds in this regard.
Replication matters. The echo chamber of peer review much less so.
I agree, science has become a form of writing and the peer-review will most likely figure out if you are familiar with that form.
[0] https://en.wikipedia.org/wiki/Electromagnetic_absorption_by_...
GE lobbied for 2.4 instead so they could emit a noisy harmonic from a crystal based 1.2 system so the FCC agreed.
Source: national archives documents I researched
In 1952, a paper called Tubes for dielectric heating at 915 megacycles said this, "Dielectric heating can be much faster at microwave frequencies. Because leakage radiation is large enough to interfere with communications, heating is best done at assigned frequencies. The bands at 915 and 2,450 megacycles are most useful."
"The plan which is, recommended by the United States provides for certain discrete frequencies, with appropriate guard bands, for those industrial scientific and medical devices which cannot be shielded effectively. This assures a minimum disruption of vital communication services. The allocation of frequencies for this purpose is justified because of the tremendous investments in equipment and the public demand for the various services performed, together with the harmful interference to radio communications which would result if such devices were scattered indiscriminately throughout the spectrum. The frequencies proposed are:
13660 kHz
27320 kHz
40980 kHz
2450 MHz"
http://handle.itu.int/11.1004/020.1000/4.62.51.en.108, page 628.
I also wonder if anyone actually experimented with microwaving their dinner at 10GHz or if that was just an educated guess. X-band magnetrons for radars are widely available though, so I would not be surprised if that was coming from practical experience...
"effective penetration and heating favors wavelengths in the cm range (1–30 GHz). Higher frequencies cannot penetrate sufficiently, and much lower frequencies require very high fields, and can have poor coupling unless making use of direct contact or inductive heating. In the years following WWII, emphasis was thus placed on frequencies in the low GHz region, where both the historic development of microwave power sources and serendipity converged."
https://ieeexplore.ieee.org/stamp/stamp.jsp?arnumber=9393469
water can get shaken up by a wide band of frequencies
The fact that no rat behavior change was reported until the 3 week mark heavily suggests external factors; hardly a cumulative effect as any long exposure effect would display.
Moreover an interesting paragraph:
> The average rectal temperatures of rat were observed to be 33.71±0.56 (control), 35.3±0.63 (EMR-900 MHz), 35.48±0.67 (EMR-1800 MHz) and 36.96±0.55 (EMR-2450 MHz) before and 33.91±0.82 (control), 35.5±0.51 (EMR-900 MHz), 35.66±0.60 (EMR-1800 MHz) and 37±0.78 (EMR-2450 MHz).
Seems to indicate the 2450 MHz rats were ill or otherwise stressed (rat body temperature hovers around 35.5, though it can increase at night), but no verification or mention is done on this whatsoever. I honestly believe many of effects described in the paper can be explained with the body temperature differential.
Also worth mentioning:
> The animals after being exposed to 900, 1800 and 2450 MHz EMR, the average power density was found to be 0.1227 W/m2. While the overall value of whole body average SAR was found to be approximately, 0.0227, 0.030 and 0.0616 W/kg.
Again not my field but I doubt 120mW/m2 can result in 50% absorption (61.6mW) per kg of rat. That means 2 kg of rats would absorb 100% of the radiation, while obviously not covering a full square meter. Please correct me if I misunderstood something.
I'm not saying that 2.4GHz radiation has no ill effects, there's tons of research on rats since the inception of the microwave, but it generally show changes at higher (and certainly more clear) SAR levels.
So is this [0].
[0] https://juniperpublishers.com/ofoaj/OFOAJ.MS.ID.555850.php
"Peer reviewed" does not necessarily mean high-quality or true.
Reading the study doesn’t inspire a lot of confidence in their methods. They make a lot of basic errors like listing dB figures (a relative term) when I think they mean dBmw (an absolute measurement).
They tested multiple frequencies but for some reason only 2450MHz showed significant effects. 900MHz and 1800MHz showed no effects, despite 1800MHz being relatively close to 2450MHz.
They also didn’t use very many rats for each group. Only n=6 per frequency, which were further divided into n=3 for some of their measurements because they couldn’t use the same rat for both tests. They also chose a lot of stress-related measures which are known to be heavily influenced by mishandling the rats (e.g. if a researcher accidentally dropped one during handling)
Unless someone can replicate these results and do it with more rats, I suspect the results are likely from one or maybe two rats having abnormal baseline results and that being amplified by the ultra-small sample size.
As for relevance: Unless you’re standing in close proximity to a high-gain, directional antenna emitting continuous wave tones (not intermittent modulated WiFi packets) then your WiFi exposure won’t come anywhere near what they used for these experiments. Inverse square law and omnidirectional antennas mean that very little WiFi energy even makes it to people near a WiFi router.