Are there any health concerns for these GSM & microwave antennas? - Page 1
Forum section: electronics / general

author: sam1000islands
author_rank: Newbie
timestamp: May 31, 2019, 03:58:13 am
content: Are there any health concerns for these GSM & microwave-link antennas?There are many GSM antennas installed beside residential windows and I can see one microwave link on the back too!This is in Montreal, Canada.

author: timelessbeing
author_rank: Frequent Contributor
timestamp: May 31, 2019, 04:22:26 am
content: I would be more concerned with the damage to property value. Looks how ugly the antennas are. They made zero effort at concealing it.

author: Miyuki
author_rank: Frequent Contributor
timestamp: May 31, 2019, 04:39:45 am
content: Those antennas are directional and have relative low power. So totally safe on back side of them.I agree this is ugly installation and also here can be concern about mechanical damage to building and roofAnd cooling can make annoying noiseThose systems use power levels in watts to tens of watts so nothing huge even in front of themBut you do not want to stand in front of hundreds or even thousands watts antenna. If you dont want to be a tasty roasted chicken

author: Ampera
author_rank: Super Contributor
timestamp: May 31, 2019, 05:03:56 am
content: This is something that's been discussed here before, so I'm going to provide my personal view and opinion. This is as I understand it, and may not be perfectly correct.Radio transmissions/antennas produce EM radiation, the same sort of wave/particle based field emission of photons that you would get out of a light bulb. EM radiation /totally/ can cause serious harm to biological organisms, but that doesn't mean all EM can or will. Energy and frequency of the wave are the two key contributing factors to EM's potential danger to organic tissue. High frequency, yet lower power EM like X-Rays are ionizing, meaning they can knock electrons off atoms, and break chemical bonds. Low frequency, yet high power EM like microwaves within a microwave oven, when concentrated, can cook you a very hot, but also very soggy burger. High frequency EM in the visible spectrum however, is not ionizing, and we tend to be able to take fairly large amounts of it directly before it starts causing serious damage.GSM towers in the US are limited by the FCC to a transmission power of 500W per channel, and considerably less the lower down and closer to people it is. While this might seem like it's nearing the sort of power you'd reheat your leftovers in, the critical difference is that with cell towers, the radiation is dispersed into wide open space instead of concentrated into one location like in a microwave oven. It's the difference between the sun not burning a piece of paper, and the sun burning a piece of paper under a magnifying glass.People have explored the potential for more minute issues, like the effecting of human sperm, which tends to be very sensitive to warmer temperatures (supposedly why testes hang). The issue is you have a lot of people who will throw all science out the window to prove their point that RF-EM bad.Consider this, cell towers might operate in the hundreds of watt range, but TV and radio transmission towers for the last century have been operating in the kilowatt to megawatt range, and like in the case of transmitters on top of tall buildings, have been very very close to people. Understanding the potency of EM increases as its energy increases, at least logically, if there is a serious health risk, it would have been noticed by now.The risk, or rather effect, is in that EM can cause water to heat up. People experimenting with high energy RF-EM /have/ been burned before when the energy was concentrated and directed, and there is a level at which RF-EM is dangerous or potentially lethal, but I do not personally believe that the localized energy levels at which we enjoy radio are anywhere near enough to cause harm.

author: Red Squirrel
author_rank: Super Contributor
timestamp: May 31, 2019, 06:21:47 am
content: They are about 40w, however these are designed to be installed in towers, not on buildings, so the laws/regulations for power output probably take the height of towers into account. That's one heck of an ugly installation too, and I'd hate to be the guy that has to go do work on those. Does not look like there is easy access.What I'm not a fan of is what they want to do with 5G and have a bunch of transmitters everywhere. I saw a pic of one that is on a hydro pole and it's literally like 5 feet from someone's window. That can't be healthy. Even in low power levels, if you are exposed to it for a long time I'm sure it starts to have long term effects.

author: ogden
author_rank: Super Contributor
timestamp: May 31, 2019, 06:32:06 am
content: Microwave dish with it's highly directional beam is no health hazard unless you put parts of your body directly in front of it.Regarding mobile sector antenna - general public exclusion zone usually extends up-to 10m in front of antenna.Picture from mobile site safetyinstructions(exclusion zone for workers):Further reading

author: timelessbeing
author_rank: Frequent Contributor
timestamp: May 31, 2019, 06:59:40 am
content: Quote from: Red Squirrel on May 31, 2019, 06:21:47 amParanoia.The power density of the sun's radiation on the surface of the earth is approximately 1.4 kW/m2If you say that antenna is 40W, then by the time it gets to you (inverse square law and all that), you're talking about fractions of a milliwatt/m2.

author: Red Squirrel
author_rank: Super Contributor
timestamp: May 31, 2019, 06:03:07 pm
content: Quote from: timelessbeing on May 31, 2019, 06:59:40 amDoesn't the Earth's magnetic field protect from the sun's radiation though? If it was not for that we'd actually be in great danger. Heck even then I stay out of the sun since I'm a ginger... different kind of radiation though.The sector ones are directional so they arn't too bad since they arn't pointing in the building, but the 5G ones I've seen appear to be omni. Like this one:https://imgur.com/gallery/DdIrcGBI don't imagine it's harmful just going near for a bit, I'm more thinking long term. Think of a microwave oven, the longer you put something in it the more it cooks, so imagine a microwave oven where you can dial it down to say, 1 watt, and you put something in it for a year. It will eventually cook. Or is there a point where the radiation is too weak and just does not penetrate the skin far enough?

author: apis
author_rank: Super Contributor
timestamp: May 31, 2019, 06:31:38 pm
content: Quote from: Miyuki on May 31, 2019, 04:39:45 amLooks like one of them is pointing across one of the balconies though.

author: ogden
author_rank: Super Contributor
timestamp: May 31, 2019, 07:00:02 pm
content: Quote from: Red Squirrel on May 31, 2019, 06:03:07 pmMisleading appearance. 5G uses phased array beamsteering with better directivity than 3-sector antennas (of LTE)

author: apis
author_rank: Super Contributor
timestamp: May 31, 2019, 07:19:45 pm
content: How does that help if the beam pass through your living room?

author: jmelson
author_rank: Super Contributor
timestamp: May 31, 2019, 07:46:09 pm
content: Quote from: Red Squirrel on May 31, 2019, 06:03:07 pmCan you see the sun? If so, then the magnetic field is NOT protecting you from it. Light and radio waves are a form of radiation.What you are thinking of is the solar WIND, which is charged particles, and therefore does interact with the magnetic field.It gets diverted to a small area around the poles, that's what the aurora are, the solar wind following the magnetic field down to earth.Jon

author: Red Squirrel
author_rank: Super Contributor
timestamp: May 31, 2019, 08:09:34 pm
content: Quote from: jmelson on May 31, 2019, 07:46:09 pmI thought we were talking about RF spectrum. But even so, the light from the sun CAN harm you, but it is easy to block. That's why you wear sun screen or stay in shade. Replace an antenna with a 40w bulb and it won't be the same as 40w of RF in terms of energy hitting you. It's a different kind of energy. Even if you were to stick a UV bulb in the pole the walls of your house will block it, and think even window glass will.I'm not saying 5G *IS* harmful, but I just think we also can't be wishy washy about it, I do think it is a concern to have RF at such close proximity to people and should at very least be studied independently. (and not by the industry since of course they'll say it's safe).It's not so much short term exposure that's a concern, it's long term. There are lot of things in history that we thought were safe but turned out to be bad long term, such as asbestos exposure. Unfortunately it took many people dying before we found out and did something about it. I just feel we need to be more proactive with this sort of thing.

author: apis
author_rank: Super Contributor
timestamp: May 31, 2019, 08:22:45 pm
content: There is a lot of confusing terminology regarding radiation. Beta-radiation is actually electrons while alpha-radiation are helium ions. Any charged particle will beaffectedby a magnetic field. UV, X-rays and Gamma-radiation are electromagnetic waves of shorter wavelength than visible light, i.e. high energy. Electromagnetic waves are not affected by magnetic fields, some of it is blocked by the atmosphere though (ozone in the stratosphere). RF and microwaves have lower energy than light so it's not going to cause the kind of mutagenic damage you get from the higher energy radiation (ionising radiation).There could still be other ways that low energy em-waves could have detrimental health effects though, at the very least it can cause heating (think microwave oven). If RF/microwaves were super dangerous we would have noticed by now though.

author: timelessbeing
author_rank: Frequent Contributor
timestamp: May 31, 2019, 08:51:36 pm
content: Quote from: Red Squirrel on May 31, 2019, 06:03:07 pmIt protects us from cosmic waves, solar flares and wind etc. It does not block light. The 1.4kW/m2 figure is at thesurface.Quote from: Red Squirrel on May 31, 2019, 06:03:07 pmQuote from: Red Squirrel on May 31, 2019, 08:09:34 pmNo. It's ALL EM radiation. Nobody is wish washy about it.Quote from: Red Squirrel on May 31, 2019, 06:03:07 pmDo you know anybody who stands 2m away from an antenna 24/7? It's more like walking in an out of the sun. And like I said, the sun is more powerful. This is total paranoia.

author: timelessbeing
author_rank: Frequent Contributor
timestamp: May 31, 2019, 08:58:22 pm
content: Quote from: apis on May 31, 2019, 06:31:38 pmDo you have a wifi router at home?Quote from: apis on May 31, 2019, 08:22:45 pmPerhaps in the range of picowatts on the surface of your skin. The sun will heat you more.

author: ogden
author_rank: Super Contributor
timestamp: May 31, 2019, 09:13:51 pm
content: Quote from: Red Squirrel on May 31, 2019, 06:03:07 pmIt won't. For same reason you can't cook stake using candle - heat dissipation.Quote from: apis on May 31, 2019, 07:19:45 pmTrue. W/o beam passing through your room you can't have luxury of 5G speeds up-to 10 Gbps. Anyway talk about RF beams w/o specifying power density per certain area is pointless. With same success we can talk about radiation you receive from electric grid surrounding you.

author: apis
author_rank: Super Contributor
timestamp: May 31, 2019, 09:29:05 pm
content: Quote from: timelessbeing on May 31, 2019, 08:58:22 pmThe power of that is a few milliwatts iirc. My microwave at low setting is 100 WYou are probably right, it's paranoia, still, would make me uneasy to sit in a beam of several watts.Quote from: timelessbeing on May 31, 2019, 08:58:22 pmRF pass through the body, light is blocked by the skin.

author: ogden
author_rank: Super Contributor
timestamp: May 31, 2019, 09:32:11 pm
content: Quote from: apis on May 31, 2019, 09:29:05 pmIf RF pass through meaning do not lose power by heating your body - then it is harmless.

author: apis
author_rank: Super Contributor
timestamp: May 31, 2019, 09:37:32 pm
content: It's not completely transparent. The body absorb some amount of the radiation depending on wavelength. A microwave oven doesn't only heat things on the surface after all.

author: timelessbeing
author_rank: Frequent Contributor
timestamp: May 31, 2019, 09:42:52 pm
content: Quote from: apis on May 31, 2019, 09:29:05 pmOK now do the math for the energy density at the minimum required distance from a cellular antenna.I'm not sure what your microwave has to do with this.Quote from: apis on May 31, 2019, 09:29:05 pmIs that so? Which frequencies specifically?Even if it did, RF that passes through my body is uninteresting. If you wanted to know about interactions then you would be more interested in RF that is absorbed by the body.

author: apis
author_rank: Super Contributor
timestamp: May 31, 2019, 10:05:14 pm
content: Quote from: timelessbeing on May 31, 2019, 09:42:52 pmYou do it.If you have a cell tower antenna of 20W that is focused in a tight beam (think laser, i don't know how tight those beams are in reality though) and that beam pass through you, you get all the 20W through you.Quote from: timelessbeing on May 31, 2019, 09:42:52 pmIt uses a similar frequency.

author: chris_leyson
author_rank: Super Contributor
timestamp: May 31, 2019, 10:28:47 pm
content: QuoteNo it isn't, it's 1kW at 10% duty cycle or 1200W at 8% duty cycle. The 100W setting is just the average power delivered, peak power is still 1kW or 1.2kW for a larger oven with a higher power magnetron. Just saying, no disrespect intended.Anyway, I wouldn't worry too much about GSM antennas, just don't stand in front of them.Exposure limits, in terms of heating biological tissue, are usually measured in mw/cm2and even then it is frequency dependant.

author: Zero999
author_rank: Super Contributor
timestamp: May 31, 2019, 10:36:05 pm
content: Quote from: sam1000islands on May 31, 2019, 03:58:13 amOf course radio waves don't cause cancer or any health problems at low intensities, as mentioned above they have too lower energy to do that.Yes, RF can cause tissue damage by heating. Microwaves are generally more dangerous than infrared because they penetrate deeper and can heat tissues which are more temperature sensitive, such as the brain. They're also invisible and can cause eye damage, which also applies to infrared, when the energy is concentrated, as in a laser.Quote from: chris_leyson on May 31, 2019, 10:28:47 pmIt depends on the microwave. Older ovens did that: simply PWM'd the magnetron at a low frequency, but more modern inverter types actually adjust the current in a linear fashion, so setting a 1kW oven to 10%, will actually give 100W of continuous power, rather than 1kW, 10% of the time.

author: NiHaoMike
author_rank: Super Contributor
timestamp: May 31, 2019, 10:41:05 pm
content: Quote from: chris_leyson on May 31, 2019, 10:28:47 pmInverter microwaves actually do turn down the power rather than switching on and off a few times per minute. That helps to avoid temperature variations with items that have a small thermal mass/thermal conductivity compared to microwave absorption.

author: chris_leyson
author_rank: Super Contributor
timestamp: May 31, 2019, 11:08:33 pm
content: QuoteSome ovens with inverters still use PWM, it's just at a higher frequency whilst others tweak the heater and anode voltage and get a little power control that way. Impedance match becomes a big problem when you try to tweak magnetrons.

author: ogden
author_rank: Super Contributor
timestamp: May 31, 2019, 11:11:17 pm
content: Quote from: apis on May 31, 2019, 09:37:32 pmNot that long ago RF passed through the body but now it does not anymore?Quote from: apis on May 31, 2019, 09:29:05 pmQuote from: apis on May 31, 2019, 10:05:14 pmIt does not work like that. There are antenna beamwidth and free space loss at work.

author: apis
author_rank: Super Contributor
timestamp: May 31, 2019, 11:49:31 pm
content: It was wrong to say transparent perhaps, but longer wavelengths penetrate deeper into the body. Microwaves doesn't only affect the surface of the skin."the 2.45 GHz frequency microwaves commonly used in microwave ovens can deliver energy deeper into the tissue; the generally accepted value is 17 mm for muscle tissue.As lower frequencies penetrate deeper into the tissue, and as there are fewer nerve endings in deeper-located parts of the body, the effects of the radio frequency waves (and the damage caused) may not be immediately noticeable. The lower frequencies at high power densities present a significant risk."17 mm is less than I believed to be honest. To those actually interested, this article was pretty detailed (although disturbing):https://en.wikipedia.org/wiki/Microwave_burn"An engineer replaced a woodpecker-damaged feed horn of a high-power microwave antenna, a 15-meter dish at an Earth station of a television network, using a cherry picker. After finishing, he sent his technician to power up the transmitter, and attempted to lower the cherry picker down. The engine failed and the engineer was stuck next to the antenna, outside of its main lobe but well within the first sidelobe. The technician, unaware that the engineer was still close to the antenna, powered it up. The engineer was exposed to an intense microwave field for about three minutes, until the error was realized. There were no immediate symptoms; the next morning the engineer detected blood and solid matter in his urine, and visited a doctor, who found blood in stool and massive bowel adhesions. The engineer's medical problems lasted for many years."Microwaves are not harmless.Quote from: ogden on May 31, 2019, 11:11:17 pmIt was a simplified explanation, if you have a very high gain directional antenna you can get very high power far away from the antenna in the beam direction. You might want to google "parabolic antenna" as an example.

author: ogden
author_rank: Super Contributor
timestamp: May 31, 2019, 11:56:13 pm
content: Quote from: apis on May 31, 2019, 11:49:31 pmI don't have to. If you think that 1 degree RF beam is "laser" then so be itAlso it shall be noted that whole surface of parabolic antenna is RF radiator. RF power of hi-gain "dish" is spread across it's whole surface.

author: apis
author_rank: Super Contributor
timestamp: June 01, 2019, 12:02:51 am
content: Quote from: ogden on May 31, 2019, 11:56:13 pmA laser is analogous, it's a focused coherent beam of electromagnetic radiation. And maybe you missed the "i don't know how tight those beams are in reality though" part.

author: ogden
author_rank: Super Contributor
timestamp: June 01, 2019, 12:06:58 am
content: Quote from: apis on June 01, 2019, 12:02:51 amNo. I did wonder instead - that you have argument about subject you don't know much. Kinda flat earth discussion

author: apis
author_rank: Super Contributor
timestamp: June 01, 2019, 12:12:06 am
content: Quote from: ogden on June 01, 2019, 12:06:58 amIf you think I'm so wrong then maybe it's you who don't know much.Not sure what your problem is but I have no interest in bickering with you.

author: ogden
author_rank: Super Contributor
timestamp: June 01, 2019, 12:28:15 am
content: Quote from: apis on May 31, 2019, 11:49:31 pmWith same success you can state that batteries can kill. Satellite uplinks operate at > 1KW microwave power while ground microwave links used to connect base stations of mobile networks usually have 1W maximum.

author: apis
author_rank: Super Contributor
timestamp: June 01, 2019, 12:35:23 am
content: Um, yes, of course batteries can kill?Glad you agree microwaves are not harmless, as was the whole point. You have to make sure the power levels that people are exposed to are safe which is what this thread was about.

author: ogden
author_rank: Super Contributor
timestamp: June 01, 2019, 12:41:42 am
content: Quote from: apis on June 01, 2019, 12:35:23 amYou perhaps missed but we do not talk about any microwave radiation. Obviously it may be dangerous or even deadly. Think of microwave oven. Obviously if you put your head into feedhorn of sat uplink dish or military radar, you most likely will badly suffer. Or just die. We talk about microwave dish in the OP picture. You may want to pay close attention to subject of this thread as well: "Are there any health concerns fortheseGSM & microwave antennas?".

author: amyk
author_rank: Super Contributor
timestamp: June 01, 2019, 01:27:13 am
content: Every time this topic comes up, I'm compelled to post this:https://mybroadband.co.za/news/wireless/11099-massive-revelation-in-iburst-tower-battle.html

author: vk6zgo
author_rank: Super Contributor
timestamp: June 01, 2019, 07:32:21 am
content: Quote from: Red Squirrel on May 31, 2019, 06:03:07 pmNo, it willnoteventually cook.Any type of oven needs to be able to provide enough energy to heat the thing being cooked faster than that thing loses heat.(& organic stuff, like we normally cook, is very good at losing heat)1 watt does not meet this criterion, so your "something" will remain "near as dammit" at the ambient temperature of the room in which it is situated, except a small heat rise due to putrefaction after some time.

author: timelessbeing
author_rank: Frequent Contributor
timestamp: June 01, 2019, 07:45:21 am
content: Quote from: apis on May 31, 2019, 10:05:14 pmLOL. A laser beam antenna wouldn't be very useful.Quote from: apis on May 31, 2019, 10:05:14 pmOK my headphones have a similar frequency to a taser gun. What's your point?Are you trying to compare a signal antenna to sitting inside a metal reflective box with a magnetron pointed at your head?

author: timelessbeing
author_rank: Frequent Contributor
timestamp: June 01, 2019, 07:50:50 am
content: Quote from: Zero999 on May 31, 2019, 10:36:05 pmFunny.I thought the old microwaves just turned the magnetron on an off at full blast for intervals lasting seconds. You can tell when it's on because the light would dim.I though an inverter was something that generates pulsed AC at a duty cycle.Inverter welders do. My truck inverter does. Google says it does too.

author: emece67
author_rank: Frequent Contributor
timestamp: June 01, 2019, 08:00:18 am
content: .

author: timelessbeing
author_rank: Frequent Contributor
timestamp: June 01, 2019, 08:00:22 am
content: Quote from: apis on May 31, 2019, 11:49:31 pmThe feed dishes are a completely different beast from the sector antennas that your phone talks to. The signals carry thousands of channels back to a hub station. They are high powered, tightly focused, and travel great distances. You NOT want to get close to those. But they are kept well away from people. They are placed very high up where nothing get into the path. You won't find them on apartment buildings.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 01, 2019, 08:13:01 am
content: Quote from: apis on May 31, 2019, 11:49:31 pmI find this very difficult to believe, because Earth Station antennas are known to use quite serious power,From memory, the one I had some association with was around 3kW.This is real power, which can be measured with a "dummy load" not EIRP.Anybody working with such equipment would be aware of this.With this knowledge, the possibility of a Technician turning on the transmitter without double checking that the Engineer is clear, is so remote as to be unheard of.In any case, the usual thing is for a person up in the vicinity of the front of the dish whether in a "cherry picker" or not, to be in contact with his "offsider" at all times using handheld radios.QuoteParabolic antennas normally take a "point source" of RF, then reflecting the signal from all parts of the inner parabola of the dish, convert it into effectively parallel "beams" of RF (using the classic optics convention) over an area equal to that of the dish.Edit:- This should really have read "effectively parallel rays" of RF, to fit in with the "classical optics reference.These "rays" then make up the radiated "beam".They do not "concentrate" the RF down to a point anywhere", as that would be counterproductive.The "beams" actually diverge over a long distance, but remain sufficiently parallel for a receiving dish of the same kind to intercept them & concentrate them at the feedhorn which feeds the receiver input.People get confused by the use of parabolic dishes to concentrate sunlight, but this is the exact opposite process to that used in a radio transmitting dish.EIRP does not producerealpower.A moment's thought would bring the realisation that would be an "over unity" device.

author: ogden
author_rank: Super Contributor
timestamp: June 01, 2019, 08:34:56 am
content: Quote from: amyk on June 01, 2019, 01:27:13 amI would not. Only thing that story proves - tinfoil hat activists sometimes can win their laughable argument with plain persistence. Bad press about tower could be retaliation after failed extortion attempt as well. Read carefully quote from that article:Quote

author: Halcyon
author_rank: Unknown
timestamp: June 01, 2019, 09:16:16 am
content: Quote from: sam1000islands on May 31, 2019, 03:58:13 amNo.

author: apis
author_rank: Super Contributor
timestamp: June 01, 2019, 09:20:36 am
content: Quote from: ogden on June 01, 2019, 12:41:42 amI brought up a microwave in a reply totimelessbeingto make it clear that:1. Microwaves penetrate deeper than the "surface of your skin".2. At some power level microwaves will begin to cause damage. Microwaves manage to heat meat at 100 W so it will have measurable effects at lower power levels than that.A wifi router antenna only emits a few milliwatt (at similar frequencies as a microwave) so it's not something you have to worry about, whereas I wouldn't be so quick to assume that a 40W high gain antenna couldn't potentially cause some negative health effects if installed incorrectly.The comment I made to you earlier (how does directivity help in this case?) were in response what you wrote here:Quote from: ogden on May 31, 2019, 07:00:02 pmIf you worry about the power levels in your apartment from an antenna mounted a few meters outside your window, pointing in through the window, better directivity would make things worse. That is where the laser analogy is helpful, if you have a omnidirectional radiation source (like a light bulb) the power will decrease with the square of the distance, however if you have a highly collimated radiation source (like a laser) the power level will remain fairly constant in comparison.

author: apis
author_rank: Super Contributor
timestamp: June 01, 2019, 09:43:15 am
content: Quote from: vk6zgo on June 01, 2019, 08:13:01 amWho said anything about a point?A parabolic antenna creates a collimated beam similar to a laser beam so that the power remains (ideally) constant with distance (in reality it will not be constant of course, for many different reasons). That is why such "laser beam antennas" (as someone called them) are very useful, they can transmit over large distances using low power.Fun fact: actual lasers (unlike collimated microwaves as we were talking about here) are also used this way, for example in satellite communication.Quote from: emece67 on June 01, 2019, 08:00:18 amIf they are mounted outside your window as is discussed here they are not exactly distant, so I don't find it strange if the residents would be worried. I'm not saying they should, I don't know what the beam patterns are or power levels, etc. High power RF can be dangerous though, so it's wrong to ridicule people who are worried imo.

author: apis
author_rank: Super Contributor
timestamp: June 01, 2019, 09:44:05 am
content: Quote from: chris_leyson on May 31, 2019, 11:08:33 pmI didn't know that but it makes sense, thanks.

author: ogden
author_rank: Super Contributor
timestamp: June 01, 2019, 10:30:44 am
content: Quote from: apis on June 01, 2019, 09:20:36 amNo. Massive MIMO beamforming antennas usually achieve better target signal strength in receive antenna than brute force (single) directional antenna approach - in result MIMO array needs much less radiated summary RF energy to achieve target signal strength. RF beam forming have nothing to do with beams as such. It is more like summing interference spot creation where receive antenna is by adjusting phase of RF signal fed into each antenna of the array. Simplified illustration of two antenna MIMO "beam" forming:https://youtu.be/8rMtqRObvvU?t=1QuoteCollimated light of laser is worst possible analogy to describe RF beamforming.

author: apis
author_rank: Super Contributor
timestamp: June 01, 2019, 10:58:39 am
content: Quote from: ogden on June 01, 2019, 10:30:44 amPhased arrays still create a beam of EM radiation. If you can concentrate your RF into a tight beam when transmitting to a distant point you can use less power because the power won't drop with distance as quickly as it does with an omnidirectional antenna. That also means that for a given power level, if you focus the radiation into a beam it becomes potentially more dangerous at a distance (if it's pointed at you).I'm not saying the 5G antenna are particularly dangerous, I don't know, but beam forming doesn't make it safe. What matters in the end is how much power people are exposed to at different frequencies.Quote from: ogden on June 01, 2019, 10:30:44 amI wasn't trying to describe RF beam forming though.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 01, 2019, 11:18:21 am
content: Quote from: apis on June 01, 2019, 09:43:15 amIf, say, a 20 watt source is radiated by a dish 2m in diameter, you initially start out with the radiated power disributed over an area= pi m^2, or near as dammit, 3 m^2.As distance from the dish increases, this area will diverge to be somewhat larger.if your body is perfectly circular, about 3m^2 in area, & you are very close to the antenna, you will intercept most of the 20 watts.Most people are more or less "human shaped", & will, perforce, have a smaller area, & intercept somewhat less of the original power.As you move further away & the beam diverges, you will occupy less & less of the area of the beam, & hence, intercept less of the original drive power.After about 30 or so km, the area of, even a similar sized dish to the original will intercept so little power, that if will require high gain,low noise, amplifiers in the "front end" of the receiver.Purists may take me to task for using "power"rather than "energy", here, but I wanted to be consistent with your comment.QuoteAs has already bern pointed out, therealpower output of such links is low.Further, any RF radiated into the building is wasted for its intended purpose, so both the design & mounting position of these antennas will prioritise the radiation direction to where it is supposed to go.

author: BravoV
author_rank: Super Contributor
timestamp: June 01, 2019, 12:11:14 pm
content: The real question is, if "you believed" that it affects your health, what are you going to do ? Or even sharper and bold question, what are you going to sacrifice part of your life after knowing that ?

author: apis
author_rank: Super Contributor
timestamp: June 01, 2019, 12:36:20 pm
content: If you look at these slides from Ericsson it's clear you need to take great care so that you don't exceed exposure levels around a cell tower:https://www.itu.int/en/ITU-T/Workshops-and-Seminars/20171205/Documents/S3_Christer_Tornevik.pdfBut I'm sure you guys know better than the silly people at Ericsson.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 01, 2019, 01:40:59 pm
content: I expected a bit more detail but the illustrations are pretty.Note that the thrust here is on what the limits are & what may possibly be a problem in countries with lower limits.Even the most generous limits are several orders of magnitude below anything that might, just posibly, be hazardous.The whole business is more an exercise in backside protection, in case someone decides to sue themsomewhere down the track, than anything else.

author: apis
author_rank: Super Contributor
timestamp: June 01, 2019, 01:55:17 pm
content: Pictures help build an intuition for what we are talking about instead of people talking about 2m dish antennas and beams that aren't beams, etc.Quote from: vk6zgo on June 01, 2019, 01:40:59 pmYeah, they want the limits to be raised to allow for 5G, not exactly surprising.I'm not saying 5G is unsafe if installed correctly, I'm saying when you install high power antennas you need to take great care so you don't expose people to dangerous levels of radiation.

author: NiHaoMike
author_rank: Super Contributor
timestamp: June 01, 2019, 02:02:59 pm
content: Quote from: BravoV on June 01, 2019, 12:11:14 pmUse aluminum foil to shield the room.

author: apis
author_rank: Super Contributor
timestamp: June 01, 2019, 02:23:41 pm
content: This reminds me ofCockcroft's Follies. I happen to believe civilian nuclear power is one of the safest and cleanest types of power (besides Windscale was used for weapons production) but not if you have a nonchalant attitude to safety.

author: ogden
author_rank: Super Contributor
timestamp: June 01, 2019, 03:13:26 pm
content: Quote from: apis on June 01, 2019, 12:36:20 pmSure. Ericsson agrees to everything we are telling youInmy postI already mentioned exclusion zones for (pre-5G) base stations that we see in the picture of the OP. You "missed" that post. How convenient for your debate, right?Exposure limits stated indocumentI referred to, pretty much agree to those used in Ericsson slides. It shall be noted that exclusion zones are only in front of the antenna. As all antennas are facing away from the building shown in the picture of the OP, answer to question still is: no health concerns for residents of that particular building, at least not according to regulations.I did say following:Quote from: ogden on May 31, 2019, 06:32:06 am

author: apis
author_rank: Super Contributor
timestamp: June 01, 2019, 06:55:46 pm
content: The comment I made to you earlier (how does directivity help in this case?) was in response what you wrote here:Quote from: apis on June 01, 2019, 09:20:36 amWe were talking about 5G and the antenna in the other picture that was posted,not the OP's picture. Your claim that 5G is safe because it use beam forming is simply not true. As can be seen in the slides from Ericsson they want the limits to be raised which means that 5G is going to cause higher peak radiation levels than previous generations.And to reiterate what I've said since the beginning; I'm not saying 5G is unsafe either, but when you install high power antennas you need to take great care so you don't expose people to dangerous levels of radiation.

author: ogden
author_rank: Super Contributor
timestamp: June 01, 2019, 08:00:43 pm
content: Quote from: apis on June 01, 2019, 06:55:46 pmI do not recall saying "5G is safe". If you think "misleading appearance" or "better directivity" means "safe" then you are hilariously mistaken BTW that thing on the top of the pole in "other picture" most likely is > 20 GHz comparably low power beamsteering multisector antenna with exclusion zone that most likely not even reach nearby house. Only question is - sector antenna or whatever it is in a middle of the pole. It may be violation of regulations indeed. It is absurd to believe that someone who correct your fallacies about beamforming is somehow automatically implying that said antenna is safe.

author: Zero999
author_rank: Super Contributor
timestamp: June 01, 2019, 08:59:22 pm
content: As frequencies increase, the safety hazard starts to be more comparable with infrared lasers, since the heating becomes more confined to the surface. The main added hazard is clothing is more transparent to the high microwave end of the spectrum, than far infrared.Quote from: chris_leyson on May 31, 2019, 11:08:33 pmIf the PWM is a much higher frequency than the thermal time constant, then the effect will be similar to continuous radiation. 1kHz 10% duty 1kW, won't be much different to 100W continuous wave.

author: Neganur
author_rank: Unknown
timestamp: June 02, 2019, 11:18:45 pm
content: Quote from: apis on June 01, 2019, 09:20:36 amI just wanted to point out that a microwave oven has a very different frequency than 3.5 GHz and 28 GHz microwave used in 5G. Also, in the oven the distances are very very small.At 28 GHz RF energy will definitely not penetrate skin more than a couple (that's two) mm, concrete and other building materials are a complete disaster in terms of penetration too.And you are right to be cautious at high power RF (of any frequency) if it's in touching distance (and that should not be new information). But beyond that there is no need to spread anxiety.Also, power of an omnidirectional antenna drops exactly the same per distance than any other antenna, beam steering or not.EDIT: PS. thanks for the Ericsson slides, they are very nice.

author: apis
author_rank: Super Contributor
timestamp: June 03, 2019, 12:09:26 am
content: Quote from: Neganur on June 02, 2019, 11:18:45 pmIt's the same frequency as WiFi though, as was mentioned in the comment I replied to. I thought the frequency of cellular networks varies from country to country, maybe 5G is different? But yes, you have to take frequency into account as I mentioned previously.That you don't have to be careful beyond touching distance is BS, it depends on the antenna and power and frequency and how long you are exposed.Power of an omnidirectional antenna does not drop the same per distance as a perfectly collimated beam of em radiation. If you have a narrow beam then the power is focused in that beam, and if you block the beam with your body you will be still be exposed to the bulk of radiation from the antenna. I understand what you mean but your statement is misleading at best. Beam steering doesn't make antennas inherently safe.There is no need to spread anxiety but there is no need to spread misinformation and pretend it's completely safe either.

author: Neganur
author_rank: Unknown
timestamp: June 03, 2019, 01:44:43 am
content: Perhaps we need to be more specific when we make our statements, (free space) path loss depends on distance and wavelength and not on the antenna.Receivedpower depends on both the transmitting an receiving antenna (aperture and gain) but the FSPL is the same. That is not misleading, your sentence was easy to misunderstand since you omitted that you were talking about thecompletelink loss.From your answer I now understood that you are referring to the channel (in particular shadowing or blocking). Of course the channel (path loss) is important and effects such as scattering, specular reflections, refraction/ diffraction and multi path (fading) as well as self-user effects (e.g. hand in the near field of the antenna) are very important. Especially at 28 GHz you don't want the user or anything else to block line of sight to the base station antenna if at all possible (otherwise the radio link will suffer). Even more so when you are using beam steering.I did not say that RF is safe beyond touching distance. In fact, I implied it is dangerous at high powers in touching distance and your Ericsson slides have some 1.5m that corresponds to a 10W/m2 exclusion zone at 28 GHz - OK maybe my arms aren't that long. Certainly being able to touch those things is not safe. But the ICNIRP put the safe limit to 10W/m2 so I will trust that and refer to as safe. Further away is more safe. If the exclusion zone is 25m for a theoretical maximum of 200W 3.5GHz base station then that's interesting to know. And I guess I will never be able to get that close to one of them anyway.SAR values and limits will tell you exactly how dangerous or not dangerous the exposure is, this is fairly well studied.I did not say that beam steering makes antennas safe. Nor did I use the word 'inherently'. Perhaps you mistake me for a different poster. Personally, I think that beam-forming and -steering translates into less people exposed at the same time and also more opportunity to use several links at the same time (MIMO).I think would like to agree that the placement of high power base stations needs to be done carefully. But I am sure they will.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 03, 2019, 04:28:57 am
content: Quote from: apis on June 03, 2019, 12:09:26 amThe only power that counts is real electrical power (I^2R).if your directional antenna is fed with, say 10kW that is all you have to play with, even though the antenna may have 20 dB gain in the preferred direction, for an Effective Isotropically Radiated Power of 1MW.Sounds huge, eh?, but it is never more real power (that can be used to do work), than that which is provided by the RF drive.Practical RF power (I^2R) used in microwave links & the like is usually in the low to mid tens of watts.Applying the same gain figure as above, would, for the common case of around 20watts RF, give us an EIRP of 2kW.If you now, intercept 100% of the radiated signal then apply it to a power meter, it will show you 20w.Maybe, just maybe, 20w distributed evenly over the surface of your body, may do something-- but nobody has come up with any such effect at such low power levels.There are no "perfectly collimated sources" at RF frequencies, due to limitations upon the size of dishes, or complexity of other types of "directional" antennas.Also, those "perfectly collimated rays" described in Wikipedia don't stay parallel---- they diverge over distance, sometimes quite short distances, they "scatter" due to atmospheric conditions, lose energy by exciting oscillations in conducting objects in their path, & so on.Even before any of that happens, the beam is not that "narrow".For a parabolic dish, as used for communications, it cannot be smaller in diameter than the dish is.

author: timelessbeing
author_rank: Frequent Contributor
timestamp: June 03, 2019, 06:33:38 am
content: Right. No signs of death rays beaming through people's living room so far.So back to the topic, are there health concerns? I haven't heard any. Unless somebody can cite a confirmed medical diagnosis, then why are we still talking about this? What is neurotic uneducated conjecture supposed to accomplish?

author: ogden
author_rank: Super Contributor
timestamp: June 03, 2019, 07:36:38 am
content: Quote from: timelessbeing on June 03, 2019, 06:33:38 am- Controversial discussion trolls love so much.If person openly and persistently refuses to comprehend RF wave propagation and how antennas work - most likely there are reasons for that. I am afraid that we are just wasting internet ink here.

author: apis
author_rank: Super Contributor
timestamp: June 03, 2019, 09:23:56 am
content: Quote from: Neganur on June 03, 2019, 01:44:43 amYou have to remember we are not talking about a one time exposure of a few minutes, we are talking about people who live, work and sleep right next to them, so it's important to follow the regulations. If you take all effects into account I wouldn't be so certain that the balconies of the OP's picture doesn't exceed those limit at some point. If they are installed correctly, they shouldn't, but it's hard to be certain of that from just a picture. If people take care when installing them, which I believe they do (although I'm less certain after reading the comments in this thread) it should be safe.Quote from: Neganur on June 03, 2019, 01:44:43 amSorry, I might have been overly defensive, I think we agree. I read your comment in the context of previous commenters who seem to not know what they talk about. That kind of stupid ignorance is what perpetuates conspiracy theories and put people in danger.Quote from: timelessbeing on June 03, 2019, 06:33:38 am

author: vk6zgo
author_rank: Super Contributor
timestamp: June 03, 2019, 09:44:10 am
content: Quote from: apis on June 03, 2019, 09:23:56 amThose of us who spent their entire working life around RF equipment and antennas were required to "know what they are talking about" to perform their day to day work.Part of this, is knowing that antennas at RF do not behave in the way you believe.I would back my "stupid ignorance" against your superficial knowledge, any day.if we are to liken anything to "conspiracy theories", your postings skirt uncomfortably on the edge of thatrealm.

author: apis
author_rank: Super Contributor
timestamp: June 03, 2019, 10:27:36 am
content: Quote from: vk6zgo on June 03, 2019, 04:28:57 amWhich is all we are talking about.Quote from: vk6zgo on June 03, 2019, 04:28:57 amNow you are just obfuscating. No one is talking about that, and if you think 10 kW is safe then you are sorely mistaken.Quote from: vk6zgo on June 03, 2019, 04:28:57 amWe're not talking about "20w distributed evenly over the surface of your body", and even in that contrived case "The 'normal' body surface area is generally taken to be 1.7 m2" and 20/1.7 = 12 W/m2which is over the limit. Limit guidelines in U.S. are from 2 W/m2to 10 W/m2depending on frequency. That's referring to cross sections though, not a closed surface like the body, because reality doesn't work like your example.If we looks at absorbed energy, the ICNIRP exposure limits for cellphones is 0.08 W/kg for the whole body. 20W absorbed in a 70kg person would be 20/70=0.3, way above the limit.Quote from: vk6zgo on June 03, 2019, 04:28:57 amOf course, the world is always more complex than our models, but none of that matters to the argument. I was using an ideal simplified case to explain a principle that I would have thought was obvious; if you concentrate the radiation into a beam the risk of absorbing a larger portion of the energy from the antenna is in fact increasing, not decreasing as was implied. Such a high gain antenna is more dangerous at a distance than an omnidirectional one. (Even if we were calculating the wave-function it would still be a simplification).Quote from: vk6zgo on June 03, 2019, 09:44:10 amI wasn't referring to you. That said, the best way to tell if someone doesn't know what he is talking about is if he is falling back on authority and insults instead of factual arguments.

author: ogden
author_rank: Super Contributor
timestamp: June 03, 2019, 12:45:12 pm
content: Quote from: apis on June 03, 2019, 10:27:36 amYou again conveniently ignored very important part of what was said - with high gain antenna transmitter can use much lower transmit power. Seems, you think that cell antennas are blasting max power all the time? Rest assured - they are not. Cell transmit power is regulated according to signal level of the phone. Phones will do the same in return. That's why your battery will last much longer when you are close to cell tower.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 03, 2019, 01:34:01 pm
content: Quote from: apis on June 03, 2019, 10:27:36 amDid I at any time in that paragraph, say 10kW was safe?The only reason I used that power level was as an example of how EIRP is used.QuoteAs physically realisable "omnidirectional" antennas do have "nulls" where very little radiation takes place, it is easier to consider a "isotropic" antenna.In order to produce the required signal strength at the distant receiver, to replace my example of a 20watt source with an antenna gain of 20dB, the isotropic antenna would need to be fed with 2kW.This 2kW would be radiated in all directions, & the power available for you to "absorb" at the same distance as before would not have changed.In the meantime, however, the isotropic radiator will be radiating power in directions which were previously shielded by the dish, or at least in a deep "null" if some other directional antenna is being used.By the way, you wrote:-"Such a high gain antenna is more dangerous at a distance than an omnidirectional one."I thought we were both indulging the fantasy of someone being close enough to absorb all the power radiated by the antenna.As soon as "at a distance" comes into the the situation, that conceit goes out the window.Propagation of radiated RF signals is not a lossless process, quite apart from beam divergence, which limits how much of the original "beam" may be intercepted, objects in the signal path will absorb energy."Scattering" is another phenomenon---- water particles in suspension can cause quite high attenuation of the higher microwave frequencies, whilst even frequencies around 13GHz or so can be severely attenuated by rain.If "concentrating the radiation into a beam" was the "royal road" to transmitting signals without loss, the communications companies would jump for joy.Those companies which produce Low Noise amplifiers for receiving use would not be as happy!QuoteYes, & you were the one who used the term "stupid ignorance".Your "factual arguments" fall down, in that the possibility of any person "absorbing" any thing like the total power being delivered is extremely remote.

author: apis
author_rank: Super Contributor
timestamp: June 03, 2019, 01:43:56 pm
content: Quote from: ogden on June 03, 2019, 12:45:12 pmYou keep making up strawmen.You implied the antenna inthis picturewasn't dangerous because it was using beam forming. I asked you how that helps if the beam is pointing into the house, then you got nasty. (Hint: it doesn't help, it just makes it worse).I did not "conveniently ignore" anything. We were comparing antenna types: is a high gain antenna safer than an omnidirectional antenna of a certain specified wattage, say 200W? It is not, as any RF engineer could tell you. It's actually more dangerous to stand in front of a high gain antenna (and it is safer to stand behind it).What it comes down to is how much radiation humans who live in the building are exposed to. Your attempt at obfuscating by bringing up irrelevant technical details are dishonest at best. Seems like you are only interested in downplaying the potential safety issues. No one benefits from that except conspiracy theorists.

author: apis
author_rank: Super Contributor
timestamp: June 03, 2019, 01:46:15 pm
content: Quote from: vk6zgo on June 03, 2019, 01:34:01 pmYes, in response to this:Quote from: timelessbeing on June 03, 2019, 06:33:38 amQuote from: ogden on June 03, 2019, 07:36:38 amThis discussion is over.

author: ogden
author_rank: Super Contributor
timestamp: June 03, 2019, 02:02:20 pm
content: Quote from: apis on June 03, 2019, 01:43:56 pmI did not say anything like that. You claimed "better directivity would make things worse" Ianswered"no", but there wasexplanationyou again conveniently ignore: "MIMO array needs much less radiated summary RF energy to achieve target signal strength". Only people with way too exaggerated imagination can conclude that this means "antenna in the picture is not dangerous".QuoteWhere did we talk about antenna of certain wattage? Quote from: apis on June 03, 2019, 01:46:15 pmAgreed.

author: vk6zgo
author_rank: Super Contributor
timestamp: June 03, 2019, 02:45:23 pm
content: Quote from: apis on June 03, 2019, 01:43:56 pmTalk about obfuscating!it is quite obvious that to do the same job of communication to a distant point, the Omnidirectional antenna must produce the same signal strength at that point.The only way to do that is radiate the same effective signal power.As I pointed out in my earlier posting, there are no true omnidirectional antennas in the real world, so we are stuck with the "Isotropic Antenna", which has a gain of zero.If we use this device, using my previous 20 watt source, we now have 20 watts being shared by every direction.It is immediately apparent that nobody in any direction is going to "absorb" 20 watts, but what of it?It is equally clear that to provide the same signal strength at the distant receiver, the transmitter must now increase in real power by the amount of gain previously supplied by the directional antenna.Let's use the antenna gain from my previous example, of 20dB.Increasing by 20dB from 20w gives us 2kW, so if you are in the same place, you will still absorb your 20 watts, but, as I pointed out before, we now have the rest of that 2kW radiating in all directions.There was never a possibility of changing the directional antenna for an omnidirectional one, whilst retaining the same source power.If that were possible, obviously all that was needed was (in my example), 20w EIRP, so the Comms company could just keep the gain antenna & use a very low power source. (Again in my example, 200mW.)Quote"Irrelevant technical details" on an Engineering forum?

author: vk6zgo
author_rank: Super Contributor
timestamp: June 03, 2019, 02:53:55 pm
content: Quote from: ogden on June 03, 2019, 02:02:20 pmEven his terminology is incorrect, it is the transmitter which is of a certain wattage!"Wattage"in connection to an antenna refers only to its power handling ability.QuoteIt's not over till I damn well say it is over!!

author: ogden
author_rank: Super Contributor
timestamp: June 03, 2019, 03:34:55 pm
content: Quote from: vk6zgo on June 03, 2019, 02:53:55 pmWhatever you sayBack to the track about antenna in thepicture. I would definitely not want to see such out of my window, those can radiate quite power. At max power for antennas of such size exclusion zone goes into roof of that house indeed. If somebody lives in the attic - it is not safe. Hopefully they do not use sector pointed at the house. Can't find exact model, butSmall Cell antennaof seemingly same dimensions (600mm height by 200mm dia) can take total 300W of RF power, have max 8 dBi gain. Other antennas in the list have up-to 13dBi or so. Picture attached

author: vk6zgo
author_rank: Super Contributor
timestamp: June 03, 2019, 03:44:02 pm
content: Quote from: ogden on June 03, 2019, 03:34:55 pmUnfortunately, my iPad doesn't do imgur.I tried to download the App & it told me, in effect, "go away your iPad is too old!", so I can't see it.I'll try to fire up the "real" computer tomorrow & have a look.

author: apis
author_rank: Super Contributor
timestamp: June 03, 2019, 05:30:32 pm
content: Quote from: ogden on June 03, 2019, 03:34:55 pmGlad to see that you finally admit it's potentially unsafe.Iv'e always said it's not shameful to be wrong, only to not be able to admit it.

author: timelessbeing
author_rank: Frequent Contributor
timestamp: June 03, 2019, 05:46:34 pm
content: Quote from: apis on June 03, 2019, 05:30:32 pmWhat is your bloody point? Of courseeverythingispotentiallyunsafe. Was some actual harm done or why are you so obsessed with this? Shall we now over-analyze kitchen knives and how they can cut you?

author: ogden
author_rank: Super Contributor
timestamp: June 03, 2019, 06:22:47 pm
content: Quote from: apis on June 03, 2019, 05:30:32 pmNo problems. I made mistake by guessing thatantennaon the top of the pole is > 20Gz, yet it seems that it is <= 6GHz. You better follow your mantra yourself