DIY: External antenna

[yeldoom]

http://www.poyntingdirect.co.za/pADPT-026/Adapter-cable-for-all-USB-Modems---SMAf.aspx

Is it possible to build an adapter similar to the Poynting ADPT-026 ?

 

[ginggs]

Is it possible to build an adapter similar to the Poynting ADPT-026 ?

Yes, but by the time you've traced their PCB, bought the copper clad board and etched it, you may as well just have bought one.

 

[yeldoom]

I have no idea how their adapter works (inductive coupling)... could you explain briefly?

 

[ginggs]

I have no idea how their adapter works (inductive coupling)... could you explain briefly?

The coupler is a specially designed antenna etched into a printed circuit board. The idea is that for phones and modems that do not have external connectors you bring a small antenna into close proximity with the device's internal antenna. There are losses compared to using a direct connection, about 5-6dBm I think.

 

[yeldoom]

Thanks

 

[stricken]

if you're gonna hack it, may as well do it properly. open up the USB modem and find either the onboard pigtail connector for external antennas, or solder some wires onto the connectors for the internal antenna. Then you can go nuts + no loss from induction. building an inductive coupler yourself is a big nono as the gains will be minimal (unless of course you are an expert in fractal wave theory and a ninja with a stanley knife and tinfoil/copper plate. )

 

[FrancTheTank]

or just move closer to the tower
sounds like less effort

 

[Dolby]

ginggs ... in laymans terms :

If my RSSI is -80db ... a 5db gain antenna would put me at -75db?
A 24dm grid antenna would put me at -56fb?

 

[ginggs]

ginggs ... in laymans terms :

If my RSSI is -80db ... a 5db gain antenna would put me at -75db?
A 24dm grid antenna would put me at -56fb?

I don't know of any 24dBi grid antennas for the cellular bands, but there's the LPDA-A0044 with a gain of 11dBi.

If you stick that on your roof, your RSSI should improve by a lot more than 11dBm because you are now clear of walls, cars and everything else that's at ground level.

Edit: Just tested now. I get -87dBm with an E1820 plugged into my PC with no antenna. Using the inductive coupler, about 15m of cable and an LPDA-A0044 on my roof I get -63dBm. Using v3g's descriptions, that takes me from 'workable under most conditions' well into 'excellent'.