GSM Base Station Measurement and Study on it...

Hello,
There is a base station near my home for several years. It is about 15 meter away. I work as a electronics engineer. I made some measurements in my company and home with a tool(9khz-3ghz spectrum analyzer) using a reference gsm antenna. I made these measurements for comparing signals between my company and home, so I know that it do not show exact signal output...

Results are;

* For gsm900 band with max captured signal;
1- company-> -50dbm (approximate value)
2-home -> +10dbm (approximate value)
*For gsm1800 band with max captured signal;
1-company-> -50dbm (approximate value)
2-home -> +20dbm (approximate value)

The results means that the signal in my home is 10 000 000 times more than the one in my company (as watt).

Mayba, this comparision do not prove that the base station radiate over legal signal limits... But I wonder, can it be said that the signal around my home is possibly exceed the legal limits..????

I will be appreciate for technical explanations, if possible...

Your results correspond with the propagation loss of signal power. Typically the power decreases with a square of distance from the transmit antenna (base station). In real situation, due to reflections and shadowing by surrounding objects, power levels at test antenna output may vary.
Concerning the health issues, google the values standardized in your location state for GSM band frequencies. Avoid stayng in situations where as you detected the power level exceeds +20 dBm, but make sure the power level is taken over an area normal to the propagation line. Having a home so close to the base station is possibly dangerous.
Your local authority (FCC or equivalent) should have licensed the GSM operator to locate base stations close to homes. Send them your measured values and ask for an expert statement. You may need a lawyer to run a legal proceedings but I would simply find a new home (lower cost), but inform local health authorities about your finding.

What's receiver antenna gain? Although the field strength most likely doesn't doesn't exceed limit values (even in case of a low gain antenna, e.g. a dipole), the received power is quite high for 15 m distance.

Is the field strength different from received power as relation? I thought there are related between them. Is it possible to be received power is under limits and field strength is over limit at the same time? or inverse of it?

What should be the key parameter for human health? reveived power or field strength(V/m) or another case ???

optech said:

Is the field strength different from received power as relation? I thought there are related between them. Is it possible to be received power is under limits and field strength is over limit at the same time? or inverse of it?

What should be the key parameter for human health? reveived power or field strength(V/m) or another case ???

Click to expand...

Field strength is the RF voltage at antenna terminals, the power is the square of this voltage divided by antenna impedance.

Health issues of RF power density has been widely discussed over years. There are national standards for safety, differing in different countries.

For cell phones and base stations, SAR parameter is defined as heating of tissue due to incident power.
Google the above, certainly there are books in the issue available. People talk about fears but never stop talking on cell phones...

Could you give me some information about how to measure gsm base station for seeing it is acceptable according to human health limits? Should only measure electric field strength (on the air) as V/m? Or Are there another important parameters to measure on the air?
Does Electric Field strenght changes related with frequency? should it be measured at different frequencies?
thanks for answers...

optech said:

Could you give me some information about how to measure gsm base station for seeing it is acceptable according to human health limits? Should only measure electric field strength (on the air) as V/m? Or Are there another important parameters to measure on the air?
Does Electric Field strenght changes related with frequency? should it be measured at different frequencies?
thanks for answers...

Click to expand...

I do not directly work in this area, so please refer to available sources via google.

People measure electric field strength rather below 500 MHz where calibrated dipoles can be used. Higher-frequency antennas offer power density measurements. Frequency variation are due to antennas and a bit due to wave propagation law.

As you used a calibrated antenna and a spectrum analyzer, your results of power levels look reliable.
I would recommend to follow procedures e.g. by Narda company offering antennas and equipment to evaluate power density at UHF, VHF and microwave bands.
Your measurement of +20 dBm at a location close to base-station antenna I think is of a concern. It means that 100 mW is constantly present around your body for a long time and may affect our health. Cell phones radiate 1-2 Watts but for only several minutes of a phone talk. You can google many similar cases observed as well as safety standards referring to SAR, and try to make your conclusions.

I spent my life working in fields like yours but my health was not affected. I still cannot exclude that some people are more sensitive and some health effects may be observed. I think thermal effects are possible due to cell-phone power absorption in human tissue, similar to what we feel close to a campfire. I do not but others promote uncertain dangers. A common sense is good attitude.

Actually, I have suspections about relation between high gsm power density(adding importance of "RF exposure time") and especially melanoma(which is a kind of malignant skin illness.it is most deadly skin illness)... This is just a suspect. Skin has an antenna effect. Of course, I do not know the skin reaction to gsm frequencies... But I have made a search and i saw that in a country which has higher healty electric field strength limits, has more melanoma cases... For example, england...According to my searches, England has 46V/m at 900 mhz and 61V/m at 1800mhz as gsm limits... And I read that melanoma cases much more that other countries... Maybe this thought is just a coincidence... But i think it should be studied....

Sage advice given to newbies at work: "Don't stand in front of the antenna when it's powered up, if you start to feel hot or head-achey for no apparent reason, move away from the work area."

I'm probably wrong, and had never thought about your remark concerning the skin, but thought mobile towers, etc. were more like a microwave oven - cooks from the inside outwards.

optech said:

Actually, I have suspections about relation between high gsm power density(adding importance of "RF exposure time") and especially melanoma(which is a kind of malignant skin illness.it is most deadly skin illness)... This is just a suspect. Skin has an antenna effect. Of course, I do not know the skin reaction to gsm frequencies... But I have made a search and i saw that in a country which has higher healty electric field strength limits, has more melanoma cases... For example, england...According to my searches, England has 46V/m at 900 mhz and 61V/m at 1800mhz as gsm limits... And I read that melanoma cases much more that other countries... Maybe this thought is just a coincidence... But i think it should be studied....

Click to expand...

I have never heard about any link between UHF irradiation and melanoma. Melanoma is generally caused by UV irradiation which is why the red-haired Britons suffer by it after sun exposure on beaches and high mountains..
Certainly it is a good idea to study all possibilities.
IEEE has conducted almost a 20-year study of health effects of radio exposure in humans, with no correlations found. Many adventurers insist the reverse, mainly in UK, US and Australia, where jury systems allow to play games and award high sums of money to burglars, etc.

Study and learn the truth. Good luck!