DGND3700 V1 Wifi Wireless Antenna Mod Upgrade

This is a very cheap mod if you already have tools, the RP-SMA antenna cables are 99p each delivered from China as are the antenna's - so all in its less than £4 for the parts.

I have made no scientific measurements at all - but it has improved the signal strength and quality 'a bit'. If you like a fun little project then it is worth doing, so long as you have the patience to wait a month for the bits to arrive!

Apologies for the crap iPhone pics

Drilling
Tips (If you want to do it nicely)
 * Put it on some foam or non-scratching material, the shiny black plastic case gets marked just by looking at it.
 * Measure twice, drill once. And make sure when are drilling the right end!
 * Drill pilot holes with a very small drill (I think I used a 0.8mm one in a pin-vice to start it, then a 'Rolson Spiral Push Drill' to drill it through). A decent pilot hole will stop larger drills wandering and make sure they are where you want them.
 * Work up a few mm at a time, I think the holes needed to be 6mm in the end. (stop when the threaded bit goes through!)
 * Don't rush it in your excitement! If they end up wonky they will look naff.

Measurements
So long as the wont bind with anything inside it doesn't matter, but these get them a decent distance apart and clear things inside.


 * 25mm in from the edges (use a straight rule against the side to measure).
 * 11.5mm (midpoint) in from top/bottom face edges



Cabling
On the Broadcomm miniPCI card, the lower two connectors are the 2.4Ghz and upper 5Ghz, so the 2.4Ghz need longer pigtails.

For 2.4Ghz you need longer than 20cm pigtail cables! (5Ghz 20cm is ok for the top U.Fl connector (I-PEX) and -just- ok for the lower one, if it goes directly upwards)



The distant green pcb's in the pic are the 5Ghz antenna's, the nearest are 2.4Ghz.

The ones I got U.FL IPX to RP-SMA female RF Pigtail Cable Jumper for PCI Wifi Card were oddly 26.2 cm that was ok.



Antenna
How the antenna size/'gain' effects the wave path.



I have bought several lots of omni-directional antennas of varying claimed dbi, without much difference. (Have also made my own directional ones that are miles better! ...but less useful in the house.)

2/3dBi Antennas
Here I am testing with some small (2dBi?) antenna's (one is from a DG834GT, other is from a La Fonera!)



These are the best tried so far.

7dBi Antennas
These are some 7dBi cheap ones are 2.4GHz 7dBi Wireless WIFI Antenna Booster WLAN RP-SMA for PCI Card



The signal is crap with these, do not buy them!

18dBi Antennas
These 18dBi arrived bent from DX and give off a nasty plastic smell when warm 2.4GHz 18dBi 2400~2500MHz RP-SMA Vertical Antenna

You can put them on a radiator and straighten them but it takes a while, one still needs more work in this pic, although the camera lens is distorting them a little.



They did however give the best signal (but only maginally more than the 2dBi ones (below))

=Original FCC information=

Pictures/graphs/info of the DGND3700 being radio tested etc.

https://apps.fcc.gov/oetcf/eas/reports/ViewExhibitReport.cfm?mode=Exhibits&RequestTimeout=500&calledFromFrame=N&application_id=292646&fcc_id=PY310100129

-Updated-

Above link appears to be dead, this link kindly provided by Julie.

https://fccid.io/document.php?id=1431958