Remote Pilots Australia
Well-Known Member
I know that some folks don’t believe that the internal antennas and hand proximity is an issue I can however assure you that it is.
The issue is two fold, one is “absorption” where as your body or parts of it obstruct and absorb the rf energy thus decreasing range. This happens. It is highly complex and dependant on so many variables including but not limited to the frequency, the dimensions of your body and parts there of (children are resonant at roughly twice the frequency than adults due for example lol) and even how you stand or hold your body .. i.e. do you curve your fingers around the controller or hold them straight. This affect how much of your body or limb or finger is acting as a radiator or a dielectric (antenna or absorber) and at what frequency. I’ll be honest, I went looking for some articles or studies that I could link here that would do a better and simpler job of explaining this than I can and gave up. There are plenty of articles out there but it is such a complex field that even I as a Telecommunications Technician found it heavy going. Don’t let that dissuade you doing your own research if you wish. I don’t expect anyone to just take me at my word.
Saying that proximity to your body is not relevant because mobile phones can be held up to your head with no loss of performance is disingenuous. Holding up the phone to your head most certainly does degrade radiation patterns and radiated field strength. Mobile phones vary their output based on the signal to the cell tower. When you pick it up from your desk and put it beside your head it ramps up the transmit power. Also unlike your drone where you have a direct line of transmission between the controller and aircraft the effect of multiple cell towers is more or less a “diversity array”. If putting it up to your head causes the signal to degrade enough to the tower on the other side of your head then it connects to another tower. Your drone does not have that option.
The argument about cell phone radiation safety was never about cell damage through radiation effect. Mobile phone signals like your drone are all “non ionising” radiation. It causes no cell damage as it passes through you *provided* it does pass through you. It’s when it does not pass through you and is absorbed by the tissue that the alleged damage is caused by heating to the tissue. This heating has been proven to take place in myriad studies there for the signal is to a greater or lesser degree being absorbed Q.E.D.
The other issue is the impedance of your body parts at distances less than one wavelength from the antenna (between 5 and 12cm at the frequencies we are talking about) does detune the antenna by changing it’s apparent resonant length. This makes a noticeable difference.
There are other factors I won’t even go into here such as the proximity of your hands has a tendancy to cause changes to the polarisation of the signal due to acting as radiators where not an absorber.
Once again, best advice is keep your hands as far to the rear of the controller as practicable and don’t put your fingers at the front of the controller unless required to manipulate the controls.
How much these variables actually effect the range you get to your drone is open to debate and would take equipment and testing beyond the scope of any of us here I suspect but I for one am totally satisfied that they are a factor.
Regards
Ari
The issue is two fold, one is “absorption” where as your body or parts of it obstruct and absorb the rf energy thus decreasing range. This happens. It is highly complex and dependant on so many variables including but not limited to the frequency, the dimensions of your body and parts there of (children are resonant at roughly twice the frequency than adults due for example lol) and even how you stand or hold your body .. i.e. do you curve your fingers around the controller or hold them straight. This affect how much of your body or limb or finger is acting as a radiator or a dielectric (antenna or absorber) and at what frequency. I’ll be honest, I went looking for some articles or studies that I could link here that would do a better and simpler job of explaining this than I can and gave up. There are plenty of articles out there but it is such a complex field that even I as a Telecommunications Technician found it heavy going. Don’t let that dissuade you doing your own research if you wish. I don’t expect anyone to just take me at my word.
Saying that proximity to your body is not relevant because mobile phones can be held up to your head with no loss of performance is disingenuous. Holding up the phone to your head most certainly does degrade radiation patterns and radiated field strength. Mobile phones vary their output based on the signal to the cell tower. When you pick it up from your desk and put it beside your head it ramps up the transmit power. Also unlike your drone where you have a direct line of transmission between the controller and aircraft the effect of multiple cell towers is more or less a “diversity array”. If putting it up to your head causes the signal to degrade enough to the tower on the other side of your head then it connects to another tower. Your drone does not have that option.
The argument about cell phone radiation safety was never about cell damage through radiation effect. Mobile phone signals like your drone are all “non ionising” radiation. It causes no cell damage as it passes through you *provided* it does pass through you. It’s when it does not pass through you and is absorbed by the tissue that the alleged damage is caused by heating to the tissue. This heating has been proven to take place in myriad studies there for the signal is to a greater or lesser degree being absorbed Q.E.D.
The other issue is the impedance of your body parts at distances less than one wavelength from the antenna (between 5 and 12cm at the frequencies we are talking about) does detune the antenna by changing it’s apparent resonant length. This makes a noticeable difference.
There are other factors I won’t even go into here such as the proximity of your hands has a tendancy to cause changes to the polarisation of the signal due to acting as radiators where not an absorber.
Once again, best advice is keep your hands as far to the rear of the controller as practicable and don’t put your fingers at the front of the controller unless required to manipulate the controls.
How much these variables actually effect the range you get to your drone is open to debate and would take equipment and testing beyond the scope of any of us here I suspect but I for one am totally satisfied that they are a factor.
Regards
Ari
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