HF35C EMF Meter – My Review

I've been wanting to write this review for a long time, I'd heard so many great things about the HF35C.

If you're new to this subject; the HF35C measures a form of electromagnetic fields (EMFs) called radio frequency, or RF, radiation.

First lets look at the technical side.

Technical Specifications

HF35C with antennaHere's the technical specification as per the manufacturer:

Frequency Range: 800 MHz to 2700 MHz (2.7 GHz)

Measurement Range: Power flux density (PFD) 0.1 to 1999 µW/m²

Basic accuracy including linearity tolerance : +/- 6dB

Display: Zero offset and rollover +/- 9 digits

Microwave Sensor: Logarithmic periodic antenna

Audio: Identification of pulsed radiation sources by means of an acoustic signal proportional to the modulated frequency

Power supply: 9 Volt alkaline manganese battery (included). Average operation time 6 to 7 hours.

Low-Battery indication, auto-power-off

Signal Rating: Display of peak and average value (switchable)

Warranty: 2 years warranty

Weight: 0,49 kg

What Can You Measure With The HF35C EMF Meter?

You can use this meter to measure EMFs from the following sources:

– cell phones

– cell phone towers

– Wireless video games (like the Xbox or Sony Playstation etc)

– smart meters

– Wifi

– Cordless DECT phones

– Bluetooth

– Digital baby monitors

– Digital TV Broadcasts

– Audio/Video Sender Receivers

– Wireless burglar alarms

– Microwave ovens

and more.

How To Use The HF35C EMF Meter

HF35C in boxThe HF35C is delivered with external antenna. When you open the box this is what you see (picture on the right). Remove the contents of the box, insert the battery (supplied), clip the antenna to the top of the meter and screw the antenna cable into the socket. You're ready to go.




Screen Shot 2014-04-11 at 15.02.13

This meter is simple to operate, its got just 3 buttons and an audio knob all situated above the display (as shown in this close up). The button on the bottom right is the power button, slide it up vertically to switch on. Use the audio knob to set the volume to a level where you can comfortably hear whats going on. Hold the meter with your arm slightly outstretched and start moving the meter around slowly, methodically, in all directions all the time listening for any signal and watching the LCD display. The display always gives readings in microwatts per square meter [ μW/m2 ] but there are two settings. If you are in a location where the readings are low then you want to be on the fine grain setting (you slide the button above the power button to the top). If you are in a location where the readings are high then slide the button down to read up to 1999 µW/m².

You can also choose between displaying peak and RMS in the display. The RMS setting is used by for certain official limits but for general use the peak setting is the most appropriate.

Here is a video I made which gives a brief introduction of the HF35C:

And here is another video which shows the HF35C as I get up a bit closer to a cell tower:

What I Like About This Meter

The thing I really like about this meter is that its a true directional meter. Which means its useful for determining where RF radiation is coming from. This is a really important feature.

Does that mean you can just point the meter in a certain direction to know what the radiation is in a particular location from that direction? Not exactly. RF radiation is reflected and reverberated in practically any environment. Outside in a rural environment if you point point the meter in different directions you should be able to pinpoint the source of RF radiation exposures.

But sometimes this can be difficult to do if you are in an environment where there are metal and other reflective surfaces which cause the radiation to bounce round. This is particularly true indoors. Nevertheless this meter does have true directional capability which few meters in this price range can offer.


The directional capability comes at a price. When the antenna is fitted on the top of the meter it makes this meter bulky and quite fragile. If you're out and about with this meter you're best advised to keep it in the box when you transport it. Take it out of the box when you want to use it and mount the antenna. Its easy to do but if you're in an area where there are people you might get some strange looks. This meter is not discreet.

2 other drawbacks:

  • the frequency range. This meter measures from 800MHz to 2,7 GHz which is not bad. But there are a growing number of devices that work in a higher frequency band (some WiFi) or lower frequency band (some smart meters), in which case your meter won't measure anything.
  • the measurement units. For RF measurement for health V/m is considered the best unit of measurement because it indicates peak signal strength remember some devices have peak power levels up to 100 times more than their average power levels.

Is This The Right EMF Meter For You?

A common fallacy is that there's one EMF meter that is significantly better than any other. OK if you go into a high price bracket you get way better meters. But for what this meter costs you get your monies worth – its no surprise that this is the best selling meter made by Gigahertz. This is a great meter. But that doesn't necessarily mean its the right meter for you.

Where this meter scores is in its directional capability. Read carefully this review and compare with the other meters I reviewed. Then make your decision.

Where To Purchase The HF35C

You can buy it from this company. I've found them to be very competitive on price and their customer service to be excellent.

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  • Warren said,

    Anyone buying this meter will also likely need a 20 db attenuator (available at lessemf.com) since many sources of microwave will be over the capacity of the meter. The attenuator will move the decimal point on the read-out over by 2 places enabling you to actually see how strong a signal is.

  • Marian Mendez said,

    Thank you, Lloyd, for taking the time to produce this review of the HF 3C meter. I own the meter and find it to be quite useful. I also own the 20db attenuator which makes it possible for the meter to measure frequencies higher than 1999 micro watts per meter squared. We found that our router has output well above that level.

    Perhaps it would be good if you could do one more review or video and show the use/benefits of the attenuator.

    Thank you again.
    Marian Mendez

  • Pat said,


    Based on your recent CDs I just ordered the acoustimeter and the others, should I know cancel those others and get this one to replace on of the others?

  • Lloyd Burrell said,

    I’m not suggesting you buy this meter instead of the one’s outlined in the program….my review is intended to enable people to form an opinion as to whether this is the best meter for them…..as always the best meter for you depends on your circumstances.

  • Alasdair Philips said,

    The HFE35C is indeed a good meter – I have one and have sold them. I also have the better HF59B meter and accessories. Gigahertz Solutions do make excellent products.

    However, my preferred general use meter – for ease of use and for frequency responseis – an Acoustimeter (designed by me and Andrew Cohen). For general carrying about I now use the AcoustiCom2 as it is smaller and gives almost as much information (and uses the same advanced RF detector which works to over 8 GHz). I rarely need more information that that gives – and my kit includes a 7 GHz professional spectrum analyser and a range of calibrated directional antennas.

    Ref. HF35C:
    (1) the directional antenna is useful – however, it does not (and can never) total the radiation coming in to a place from all directions. Nor can you just add the measurements from different directions – you need to take (ideally) 3 orthogonal axis measurements and then square each one, add them and take the square root of the total. Im my opinion you also need the excellent UBB27-G3 accessory (27 MHz to 3.3 GHz almost omni-directional anntenna) which is another 445 euro (inc 19% VAT) – which is more than the cost of the HF35C in the first place. You can by them both in a padded case for 745 euro as the HFE35C.

    (2) Even then you are not measuring most WiMax signals nor the three 5 to 6 GHz WiFi bands – which are now becoming the main WiFi/wLAN frequencies of choice and are now a significant part of most electrosmog exposures. 5 years ago the 5 GHz bands were mostly just used in upmarket commercial offices, but that has completely changed since them. The 5 GHz bands offer faster speeds and less interference and are now being very commonly and widely used. To measure those you would need an extra meter – the HFW35C (2.4 to 6 GHz) – they can be bought as a complete set (HFEW35C) for 1066 euros which is getting quite expensive.

    (3) I agree that the DG20 attenuator is almost essential. However, “it” does not correct the display reading – you also need to get the position of a 2-way switch on the side of the HF35C set in the correct position (for 20 dB or 100-fold attenuation). Not difficult, but an additional complication and I have come across many people who don’t really understand how to use it correctly get it wrong. You need the DG20-G10 attenuator instead if you are planning to use the UBB27 active antenna (see above) as that needs DC power to pass through the attenuator.

    I hope my personal comments are helpful. I have had over 40 years professional experience in measuring RF fields.

  • Etienne Francois said,

    Speaking about the HF 35 C meter I noticed that it only registers about 1999 u watt meter2. This is not enough if you come closer than 700 meter away from a cell tower. Anywhere close to a cell tower (low power)you look at about at 8000 micro watt2. For this you need the acoustimeter. You will never be sorry for buying quality.

  • Lloyd Burrell said,

    We know that adverse biological effects can occur at levels several magnitudes lower than 1999 µW/m² (BioInitiative Report 2012)….if you’re measuring EMFs for health reasons its the low levels readings you’re really concerned with….its handy to know what your readings are above 1999 µW/m² but in many cases 1999 µW/m² is too high for prolonged exposure and you will want to take steps to reduce ambient levels to well below 1999 µW/m².

  • Fran Neville said,

    Alasdair, the HF35C and HFE35C are not the same unit. for example the HFE35C measures down to CB RF frequencies about 27MHz, but the 35C starts at 800. From memory the sensitivity is also superior in the E. You are correct about the UBB27 antenna, it is virtually mandatory for serious omni measurements of total level at a 3D point. And sorry, but I have noticed in the field that a HFE35C with the omni is about twice as sensitive as the acoustimeter, for any specific frequency signals within the E35C band coverage. I have done comparative measurements… do you see the same? Perhaps you can offer a reason for the apparent variation.

    Etienne Francois, please do not confuse meter power range with the quality of measurement. Yes the HF35C only measures to 2000uW/m2 but (a) this can be attenuated as pointed out by many here and (b) there is significant cause for concern by the time you get to that number… for the purposes of biological significance all numbers above that are somewhat academic, and all mean “get away from the source”.

    Lloyd, you should consider a review of the omni antenna for this unit(and perhaps HFE35C+HFW or HF58/59) as it really is a quantum difference in the perception of signals for the building biologist, or just the interested RF victim.

  • Alasdair Philips said,

    Fran – you are correct and I was wrong – I forgot that it was the HFE35C with the UBB27 antenna that we used to sell and not the basic HF35C. The only Gigahertz Solutions meter that I now own is the HF59B + UBB27 for my own use – which turns the HF59B into the HFE59B and I thought the HF35C was similar. It isn’t – it does not measure much below 800 MHz even with the UBB27. Thank you for correcting my incorrect statement.

    I find the HF59B generally reads higher when used with the UBB27 than when used with the directional antenna supplied with it. I find the Acoustimeter generally reads between the two values – but bear in mind the peak and average values.

    The Acoustimeter average is a true (calculated) average of 1024 samples whereas the GS meter does an electronic average (or peak value depending on the switch setting) to give the value in uW/m^2. Our calculated average is usually lower than the GS one – it does depend on the signal type.

    The peak value on the Acoustimeter and the HFE35C should be similar but the UBB27 does often give higher values, especially at lower signal levels (see below). The main reason, I believe, is that the Acoustimeter is not omni- directional but is sensitive to about 180 degrees semi-circle from the back of the instrument as the LCD display shields the antennas at the front.

    We did consider an external omnidirectional antenna and do have a subminiature antenna connector inside for production testing the instrument and for a possible external antenna. Our market research showed that most of our customers did not want an external antenna for practical reasons, so we eventually decided on the internal antenna.

    Bear in mind that the HFEW35C (HFE35C + HFW35C + UBB27 in a set) come to 1066 euro compared with the Acoustimeter at only 372 euro – about one-third of the price and the Acoustimeter goes up to over 8 GHz instead of 6 GHz. You need to measure to at least 6 GHz now as there has been a major switch to using the 5 GHz WiFi frequency bands in the last few years.

    The HFEW59B set (to 10 GHz) is 2685 euro. Yes, both those more comprehensive Gigahertz sets are better than the Acoustimeter for semi-professional measurements but the costs is 3 (or 7) times more expensive.

    I did do some spectrum analysis tests in the field to investigate the HFE35C + UBB27 comparison issue and was reasonably satisfied that the main reason was the presence of frequencies between 27 MHz and 200 MHz which the Acoustimeter does not measure. Indeed the Acoustimeter is generally 6 dB down by 200 MHz to avoid picking up much of the VHF FM transmissions in the 88-108 MHz broadcast band which most of us believe are much more benign as regards adverse health effects. The difference generally seems to get much less noticeable as the microwave levels (above 300 MHz) increases and the contribution from VHF FM radio becomes less, which makes sense.

    They are all good instruments but I believe the Acoustimeter (at a third of the price of the HFW35C set) is better value for most people. We now have the smaller AcoustiCom 2 monitor which uses the same advanced RF detector as the Acoustimeter and gives peak readings with a better sensitivity of 0.01 V/m and also still the sound demodulation. That is only 183 euros and more than adequate, in my opinion, for most purposes for most people.

  • Fran Neville said,

    @ Alasdair, it is rare for me to get such a clear elucidation to questions that I raise, and for that I thank you. Your answer certainly satisfies the query about the differences between your design and that of GSs (E35), and I do appreciate that value and economy have to be part of the equation in manufacture of such devices. It is quite remarkable that you manage to build so much value into devices at either of those two price points. And it is also interesting to get some insight into the design considerations that you have employed. Yes, the low end of the band would have accounted for some variation, and the towers measured did have some emissions below the microwave, down to HF frequencies.

    Everything that you bring up is a tangent to an interesting conversation which of course is beyond the scope of the comments section of a web article, but one that stands out as rating a mention is that of the biological significance of signals in the VHF-UHF spectrum. I agree from individual experience (as someone who is perhaps physiologically attuned to some damage that can be caused by common microwave technologies, if not a very mild EHS sufferer) that these lower frequencies are more benign. However, I am reminded of a few confounding things in the literature such as non-linear relationships of biological effects; ULF (etc.) frequencies that can range down to almost DC that do seem significant (and which manifest biosignificance again in microwave pulses); as well as the epidemiological data of the Australian scientist who mapped significant cancer clusters around the high power VHF broadcast towers of the Lower North Shore of Sydney (at a time when it was still largely analog signals).

    As a brutal precis, the area of biological significance/conspicuity remains confusing to me, and the research field altogether seems like a swiss cheese of partially answered questions: one that, whilst definitely connoting that there is harm done (as evidenced BY the perpetuation of the fraudulent thermal/non-thermal dichotomy), is not so precise in its quantitative definition of the cause. I would (a) agree with all of those (Louis Slesin comes first to mind) who say there needs to be more (real) research done, in order to plug some of these gaps in knowledge of the effect of specific frequencies /amplitudes, and (b) would love to get a hold of the dossier that Barrie Trower mentions that he has, which outlines many frequencies and effects, the cumulative knowledge of decades of overt and covert research. So whilst thanking you for your comprehensive answer and not wanting to burden you with more time taken, might I ask if you know of any good reference(s) which is/are a more consolidated source, towards such a “dossier” or something similar?

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