Why 2 antennas on the 5.8ghz and why switching them?

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Anyone knows why there are 2 antennas on the 5.8 ghz signal?
 

ianzone

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Anyone knows why there are 2 antennas on the 5.8 ghz signal?
I think this is why but might be wrong,,,,,5.8 for transmission and 2.4 is telemetry and signal,,,are we talking inside the remote,if so there are 2 of these one one each side ,,same as drone there are 2 same one each side inside drone,,mine now live outside ,helps get better signal,,we'll for me anyway,if I am wrong please corect me
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ianzone

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Have you got all 4 antennas on the outside.?
Yip this ps3 was terrible on range the works when new in 2016,I should have stuck them outside ages ago,I sure it helps,can fly 1km up the beach easy and some but keep it safe now,,both sides I have out the leg front and back,,behind plastic was bad (like a windsurfer working backwards),some good but mine was bad,,bott pic is me remote at moment,,,got p4 Itelite panel with 5.8 argtec for transmission ,,,,no real cash to splash so using what I had around,,and yes took plastic covers off so less restrictions,,,,looks pretty out there but works very good
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Lol seems like that is the only way.. one has to do your own thing on these... Thanks for the reply
 
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ianzone

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Lol seems like that is the only way.. one has to do your own thing on these... Thanks for the reply
Sweet it's 3years out of warranty with 707 flights to date so not afraid to cut or chop this drone to make still work to my liking :)Opps 706,
 

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Anyone knows why there are 2 antennas on the 5.8 ghz signal?
It’s called Diversity. In this case spatial diversity. They also face opposing directions giving them pattern diversity as well. It improves signal reliability. It can be Google-d for more info.
 
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Antenna Diversity only applies to the receive side. A transmitter is typically a isotopic (Omni-directional) and diversity in transmit has no function. Yes, there are patch antennas that are also known as semi-directional (usually in a 90 or 180 degree pattern of radiation) and people seems to forget about the transmit and receive RF pattern that causes the majority of crash’s. In the receiver diversity there is a proprietary process from the manufacture in selecting the antenna to receive with in which signal levels, SNR, interference, data retry rates among others are constantly being evaluated. The best way to envision what is going on is, next time your in a car listening to the radio, when you pull up to a light or a truck pulls next to you and the radio signal fades out. If you move forwards slightly (about 1 car length), the radio signal improves. That is diversity. Typically the antennas are one wave length apart.

A popular misbelief is that having a high gain antenna makes the world better. The majority of times a high gain antenna can cause more problems than they solve, specially when used wrong. Antennas are passive devices. To get gain, one must take energy from somewhere. I.E. physics 101. Think of the RF radiation pattern (Omni-directional antenna) as being in the shape of a basketball. To get gain, the shape needs to be changed, i.e. squished to being more like a donut. You took energy and reshaped it to get a gain. Besides increasing gain of the antenna to operate further, it also causes the receive gain to ‘hear’ further, “RF noise” that is not desired and is the biggest cause of problems. In my profession as an RF Engineer, I constantly find reducing gain of an antenna makes a bigger difference then increasing. Antennas technology are definitely not an exact science. It’s more theory than anything.
 

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Antenna Diversity only applies to the receive side. A transmitter is typically a isotopic (Omni-directional) and diversity in transmit has no function. Yes, there are patch antennas that are also known as semi-directional (usually in a 90 or 180 degree pattern of radiation) and people seems to forget about the transmit and receive RF pattern that causes the majority of crash’s. In the receiver diversity there is a proprietary process from the manufacture in selecting the antenna to receive with in which signal levels, SNR, interference, data retry rates among others are constantly being evaluated. The best way to envision what is going on is, next time your in a car listening to the radio, when you pull up to a light or a truck pulls next to you and the radio signal fades out. If you move forwards slightly (about 1 car length), the radio signal improves. That is diversity. Typically the antennas are one wave length apart.

A popular misbelief is that having a high gain antenna makes the world better. The majority of times a high gain antenna can cause more problems than they solve, specially when used wrong. Antennas are passive devices. To get gain, one must take energy from somewhere. I.E. physics 101. Think of the RF radiation pattern (Omni-directional antenna) as being in the shape of a basketball. To get gain, the shape needs to be changed, i.e. squished to being more like a donut. You took energy and reshaped it to get a gain. Besides increasing gain of the antenna to operate further, it also causes the receive gain to ‘hear’ further, “RF noise” that is not desired and is the biggest cause of problems. In my profession as an RF Engineer, I constantly find reducing gain of an antenna makes a bigger difference then increasing. Antennas technology are definitely not an exact science. It’s more theory than anything.

I don't see the need to cite your background.
It would be better to cite sources or links.

There are a number of inaccuracies and assumptions in your post with regards to antenna/RF engineering.


A technical explanation of Diversity (in the context of Mobile devices):
http://pages.cs.wisc.edu/~suman/courses/707/lectures/mimo.pdf

Info on Spatial Diversity (separation):
The Myth of Half-wave Diversity Antenna Placement

DJI employs MIMO-OFDM in their products.
Further explanation:
MIMO-OFDM - Wikipedia
 
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MIMO is a form of diversity reception. swilken answer is correct except for explaining MIMO, which is more of a software defined radio (SDR) technique (software, not hardware).
 

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Multiple In - Multiple OUT.

There are various implementations.

So yes, it can be implemented in an RX only configuration and with/without SDR techniques.
But it is not the ONLY implementation and other forms are not invalid.

Like I said earlier... inaccuracies & assumptions.
 
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