Will connecting higher dbi antenna damage my wireless adaptor and computer?

Thread Starter

mw-b

Joined Mar 14, 2019
11
Hi there. I have TPLinkTLWN722N wireless adaptor. WNIC of the wireless adaptor has 5 dbi default antenna. I want to connect 16 dbi yagi antenna to my WNIC.
Will this antenna damage my computer motherboard or WNIC?
Should I consider the raspberry pi to do not risk my computer?
Should I consider cooling fan or heatsink for WNIC?

Yagi Antenna Specifications
TPLinkTLWN722N Specifications
 

SLK001

Joined Nov 29, 2011
1,548
You should have no problems with a higher gain antenna, provided it is a good impedance match for your adaptor. The better the impedance match, the less work your adaptor has to do.
 

bertus

Joined Apr 5, 2008
20,872
Hello,

Is the link correct? It reads:
2.4Ghz WiFi Antenna 25dBi RP SMA Outdoor Wireless Yagi Antenna Directional Booster Amplifier Modem RG58 Cable
It looks that has a booster amplifier in it.
That must be powered over the coax and the modem will likey not provide power.

Bertus
 

Yaakov

Joined Jan 27, 2019
1,612
Antennas are passive devices, "gain" in this case means something different than in an amplifier.

An isotropic ¼ wave radiator, a purely theoretical device, is the standard against which "gain" antennas are measured. The gain itself is based on an antennas ability to radiate the same power in a different, more compact pattern.

The antenna's impedance match to the output of the transmitter is the only thing you need to be concerned about, and that has nothing to do with gain, and should be right for any commercial antenna designed for the frequency of interest.

If the match is poor, there will be a high SWR (Standing Wave Ratio) on the transmission line, meaning more power will be reflected to the transmitter and not make it out the antenna. This can cause heat and in bad cases damage. But for modern devices, at low power, even this is unlikely to do anything except make them work poorly.
 

SLK001

Joined Nov 29, 2011
1,548
...An isotropic ¼ wave radiator, a purely theoretical device, is the standard
An isotropic radiator isn't a ¼λ wave radiator, but is instead a theoretical "point" radiator, thus it can't exist in the real world, while ¼λ radiators are all over the place.
 

Yaakov

Joined Jan 27, 2019
1,612
An isotropic radiator isn't a ¼λ wave radiator, but is instead a theoretical "point" radiator, thus it can't exist in the real world, while ¼λ radiators are all over the place.
The gain figure is over a ¼ wave dipole in free space, an impossible object not a practical antenna. You are right that it is not a pure isotropic radiator but it effectively looks like two of them.
 

Thread Starter

mw-b

Joined Mar 14, 2019
11
Hello,

Is the link correct? It reads:
2.4Ghz WiFi Antenna 25dBi RP SMA Outdoor Wireless Yagi Antenna Directional Booster Amplifier Modem RG58 Cable
It looks that has a booster amplifier in it.
That must be powered over the coax and the modem will likey not provide power.

Bertus
Where and how should I connect the booster amplifier on yagi antenna? Will antennas without booster amplifier work?
 

bertus

Joined Apr 5, 2008
20,872
Hello,

From the given page I can not see how to power the booster.
There is no supply voltage or power consumption given.

Bertus
 

SLK001

Joined Nov 29, 2011
1,548
The gain figure is over a ¼ wave dipole in free space, an impossible object not a practical antenna. You are right that it is not a pure isotropic radiator but it effectively looks like two of them.
The figure "dBd" (decibel gain over a ¼λ dipole) is gain over a ¼λ dipole in free space, a very REAL and ACHIEVEABLE object. The figure "dBi" (decibel gain over a theoretical isotropic antenna) is the gain over a non-possible isotrophic antenna.

The gain of a ¼λ dipole = 1.64 x theoretical gain of the isotrophic,
or
dBd = 2.15⋅dBi
 

Yaakov

Joined Jan 27, 2019
1,612
The figure "dBd" (decibel gain over a ¼λ dipole) is gain over a ¼λ dipole in free space, a very REAL and ACHIEVEABLE object. The figure "dBi" (decibel gain over a theoretical isotropic antenna) is the gain over a non-possible isotrophic antenna.

The gain of a ¼λ dipole = 1.64 x theoretical gain of the isotrophic,
or
dBd = 2.15⋅dBi
The idea of a dipole in free space is not possible, There is no practical antenna that acts as one. That's what I was saying. All practical dipole antennas act against ground and other influences and are not the same as the ideal of one in free space.
 

SLK001

Joined Nov 29, 2011
1,548
The idea of a dipole in free space is not possible, There is no practical antenna that acts as one. That's what I was saying. All practical dipole antennas act against ground and other influences and are not the same as the ideal of one in free space.
That's news to us antenna engineers who have been using a calibrated dipole antennas for decades to calibrate antenna ranges.
 

Yaakov

Joined Jan 27, 2019
1,612
That's news to us antenna engineers who have been using a calibrated dipole antennas for decades to calibrate antenna ranges.
Calibrated dipoles are not "in free space", they are reference antennas.

In any case, you were correct that it imprecise to conflate dBi with dBd, and I would reword that part of my answer in light of the objection. On the other hand that was a detail, not the answer.

The confusion of what "gain" is in a gain antenna leads to the belief that a gain antenna is some sort of amplifier, and so a consumer of power. This is the key part, that "gain" means something different than the usual.

I assume you agree with that.
 
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