Adding an external antenna to MP2 Phone

[Dirk van der Walt]

Hi guys,

We tried to replace an existing OpenMesh.com mesh recently with MP2 Phone units.

We did a few speed tests and the performance were unfortunately not good at all so we had to put the whole thing on ice.

I came back with the units and did some speed tests here at home and the speed seems to be fine.
(Using iperf I got speeds above 11Mb/s)

The place where we wanted to deploy these units has very thick walls and the signal strength falls a lot.

I'm pretty sure the whole slowness is related to weak signals (since we don't have the speed problems at home) and am now looking at adding some external antennas to these units.
Unfortunately my experience with antennas are limited but fortunately I can ask the community :-)

I'm in South Africa and Scoop seems to be a good place to source these things.

I think I've identified the correct pigtail cable but there seems to be two types (one a reverse polarity)

http://www.scoopdistribution.co.za/product_info.php/ufl-sma-female-bulkhead-p-491
http://www.scoopdistribution.co.za/product_info.php/ufl-sma-female-reverse-polarity-p-492

Then this external antenna seems to be fair priced and able to fit the pigtail:

http://www.scoopdistribution.co.za/product_info.php/9dbi-whip-antenna-reverse-polarity-sma-p-1032

Questions:

• Which type does the MP2 (Dragino uses) and will these reverse polarity type antenna work on them or do we need to look for a 'normal' one?
• Anything we have to specify in the WiFi config of OpenWrt when attaching the pigtail with antenna?
• Is this the best option in terms of price, antenna, place to source etc.
  

Cheers

[Song, Stephen]

Hi Dirk,

SMA and RP-SMA differ only in the gender of the internal pin of the connector.   Good blog post on this at 

http://blog.oscarliang.net/difference-sma-rpsma-connector-antenna-fpv-copter/

In short either will work on the MP2 as long as you have a UFL connector on one end to connect to the pcb and either SMA or RP-SMA on the other end depending on the connector on the antenna you have purchased.  As to which antenna to buy, if you are going to the trouble of installing an external antenna and don't need a full 360 degrees of coverage, I would be tempted to look at a sector antenna.  I believe Carlos tried that 9dbi omni that you linked to and did not enjoy much improvement.  They are more expensive but I think it is a case of you get what you pay for.

Cheers... Steve

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[T Gillett]

Dirk

I think you are probably correct about the antenna causing the issue in that situation. 

Also you have another 3dB of Tx power setting that may help.

To use the external antenna on a MS14 Dragino/MP02 board that has been built with the on-board chip antenna, you will need to make a mod to the board to direct the signal to the antenna connector rather than to the chip antenna.

The mod involves removing a 0 Ohm resistor from one position and installing one in another position.

Requires some precision soldering so proceed with caution.

You can get the boards set up for external antenna if you require.

Regards
Terry

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[Carlos Rey-Moreno]

Hi Dirk, in our deployment we are using external 8dBi omnidirectional antennas, and we have active links with around 4km. We bought them from Miro. 

Steve, we had very bad experience with some indoor antennas that we adapted for outdoor use, but these other outdoor antennas are performing well. 

In our case, we did not include a specific 0 Ohm resistor, we just bridge it with soldering metal. 

Hope it helps, 

carlos

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Carlos Rey-Moreno
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University of the Western Cape
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Cape Town - South Africa
Tel: +27 (0) 21 959 2562 Cel: +27 (0) 76 986 3633
Skype: carlos.reymoreno Twitter: Creym

[Dirk van der Walt]

Hi Carlos,

Thanks for the reply. I opened my unit and man those components are small!

I'll have to find someone that is good with a soldering iron in Bloem since I will definitely break things.
(must be the age hitting my eyes first ;-)

Cheers

[Carlos Rey-Moreno]

Hi Dirk, 

If I managed to do it I'm sure you will too! Be confident! 

carlos

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[T Gillett]

Carlos

Did you modify MP01 or MP02 ?

The MP02 board is a bit smaller than the MP01.

Regards

Terry

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[Carlos Rey-Moreno]

MP01

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