# Mystery component on Yun board?

The reason external antenna is needed is:

• On board chip antenna has average Gain -0.5 dBi
• Yun's transmit power is only 17 dBm.
• Yun is siting at metal case.
• The distance between Yun and WIFI router is far

Friis Transmission Formula with Propagation Law

• R = Maximum range for communication link
• N = Propagation Law (N=2 for line-of-sight, N=4 for urban environments)
• PT= Transmit power
• GT= Total antenna gain
• λ = Wavelength
• PR= Receiver sensitivity
• FM= Fading margin

if in urban environments;-

• Every 12 dBm receiver sensitivity gain will be double the distance.
• Every 12 dBi antenna gain will be double the distance.
• Every 12 dBm Transmitter power gain will be double the distance.

in line of sight environments;-

• Every 6 dBm receiver sensitivity gain will be double the distance.
• Every 6 dBi antenna gain will be double the distance
• Every 6 dBm Transmitter power gain will be double the distance.

http://forum.arduino.cc/index.php?topic=175577.msg1304059#msg1304059

An other reason is reduce interference.

The Omni type antenna ( build in chip antenna) has 360 degree field pattern

The pattern below is from a Yagi antenna : From this you can see the Yagi can block all other router signal outside from 60~120 degree.

Maximum Transmit Output Power in the ISM bands.

http://wisp-router.com/page.php?11

The part 15 of the FCC rules.

Did you ever find a solution for an antenna?

Any high gain 2.4 Ghz antenna will work.

• Pach Panel Antenna
• Dish Antenna
• Dipole Antenna
• Yagi Antenna
• Grid Parabolic Antenna

sonnyyu: Any high gain 2.4 Ghz antenna will work.

• Pach Panel Antenna
• Dish Antenna
• Dipole Antenna
• Yagi Antenna
• Grid Parabolic Antenna

What about people saying that it woud for after a number of cycles? Would it be a feasible long term solution?

Thanks

mortonc: ... What about people saying that it woud for after a number of cycles? ...

What do you mean?

The connector is designed for semi permanent application. It mean once connect it and leave it.

sonnyyu: ... Friis Transmission Formula with Propagation Law

• R = Maximum range for communication link
• N = Propagation Law (N=2 for line-of-sight, N=4 for urban environments)
• PT= Transmit power
• GT= Total antenna gain
• ? = Wavelength
• PR= Receiver sensitivity
• FM= Fading margin

...

To complete Friis Transmission Formula;-

• Increase receiver sensitivity, by change AR9331 with higher receiver sensitivity chip set
• Add RF power amplifier to increase Transmit power which like a lot of routers
• Use low frequency, Increase Wavelength

Above is for FYI only.

FYI;-

People make 2 Openwrt base AR9331 with high gain antenna nodes on 1 mile distance wells communications.

Just Give Me Antenna and I'll Show You the World!

Dragino (Yun compatible) MS14 has Antenna plug

http://wiki.dragino.com/index.php?title=MS14_Antenna

16 dbi Antenna

I have managed to successfully attach an external antenna to the Yun, but it is a hack.

I had misread this thread, bought a "SMA Female Plug to IPX U.FL Female Pigtail Cable" ( http://www.ebay.co.uk/itm/231098912466) , connected it to the Yun and saw no improvement.

Under a microscope, I could see that both the socket and plug were female. (see attached photos).

As I had nothing to lose, I thought I would have a go at creating a pin that would bridge the two female connectors. 1/0.6mm solid core wire fitted snugly in both connectors. I guessed at the correct length. Luckily i seemed to judge it about right and the plug is held firmly on the socket.

Amazingly, it worked. The Yun seems to auto sense the stronger signal. With no antenna connected to the SMA connector, the signal strength was about 35%. With the antenna connected, it bumped up to about 80%. I plugged/unplugged it a handful of times to convince myself it was working.

Obviously, with no soldering, this is might not be the most reliable of connections.

I would be interested to know from an RF expert whether I have managed to fluke a solution or whether the RF signal can jump the gap of a "not great" connection.

Let me know if you can reproduce my results.

Pete.

original murata connector, price not working( \$80) and height is not. I got customer engineer drawing done. but MOQ is too high. plus Intellectual property?

Case to hold custom made connector.

sonnyyu: Custom made connector:

Wow. Interesting solution, but it costs more than the Yun! No wonder you didn't go into production.

It's a bit of a hack, but I think Pete's solution is much more practical.

pete_dl: I would be interested to know from an RF expert whether I have managed to fluke a solution or whether the RF signal can jump the gap of a "not great" connection.

I'm not an RF engineer (as far as I'm concerned, RF is black magic!) but while I'm sure that the "not great gap" is introducing some reflections that may affect signal quality, it's hard to argue with the success you're reporting.

Does anybody know if there's a way for the Yun to report signal quality (or signal/noise ratio) in addition to signal strength?

ShapeShifter: Wow. Interesting solution, but it costs more than the Yun! No wonder you didn't go into production. ...

\$80 is murata price, I got quota about few \$ for 10K MOQ. I don't need 10K for my single Yun. :money_mouth_face: Plus It might be murata Intellectual property?

ShapeShifter: ... Does anybody know if there's a way for the Yun to report signal quality (or signal/noise ratio) in addition to signal strength?

`````` iw dev wlan0 survey dump
Survey data from wlan0
frequency:                      2412 MHz
noise:                          -95 dBm
channel active time:            105 ms
channel busy time:              36 ms
channel receive time:           35 ms
channel transmit time:          0 ms
...
``````

sonnyyu: ```         noise:                          -95 dBm ```

Thanks! This would be the interesting number to see with Pete's "imaginative" adapter. But of course, to really know if it's significant, it would need to be compared to the noise figure for a a "proper" adapter...

Still, it would be interesting to see Pete's noise figure with and without the external antenna.

They are completely incompatible with the U.FL type.... No amount of forcing, twisting or whining is going to get these to mate.

http://forum.arduino.cc/index.php?topic=188976.msg1574902#msg1574902

The top connector inside have to build in with forcing to connect well & cut off build in antenna.

I have replaced the original outlet with one that will mate with any ordinary antenna lead. I have mounted my Yun + sensor shield in an old wireless router case, using the antenna giving me good house wide connection I am not an R.F. engineer but can solder with a magnifying loupe to my eye, requires a steady hand

Those connector works fine with following limitations:

• void warranty
• require handyperson
• lost auto switch between int/ext antenna