DrayTek UK Users' Community Forum

Help, Advice and Solutions from DrayTek Users

Which antenna socket ?

  • livingj2
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
05 Sep 2008 22:33 #51791 by livingj2
Which antenna socket ? was created by livingj2
I'm going to fit a unidirectional antenna to my 2800VG to improve coverage a bit. There's two antenna sockets. One is apparently transmit/receive, and one is receive only.

Which is which ?

Please Log in or Create an account to join the conversation.

More
06 Sep 2008 22:11 #51799 by lorian
Replied by lorian on topic Which antenna socket ?
Really?

It's quite a while since I opened one up but I'm sure they were wired co-phased, both working in unison.

Please Log in or Create an account to join the conversation.

  • livingj2
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
06 Sep 2008 23:45 #51800 by livingj2
Replied by livingj2 on topic Which antenna socket ?

Lorian wrote: Really?

It's quite a while since I opened one up but I'm sure they were wired co-phased, both working in unison.



I'm going by the Draytek website description - "On a Vigor router with two aerials, the second aerial is for receive only. The main aerial both receives and transmits".

If they ARE just wired in parallel, that will give some interesting and not necessarily useful effects. Two antennas about one and a half wavelengths apart (which they are on the 2800) will produce a directional pattern with deep nulls - which is the opposite to what you want. I've always wondered why two antennas are fitted - for true diversity reception, you'd have them much further apart, I'd have thought. Also one vertical, one horizontal.

I wonder if a more directionally consistent transmission path could be had by actually removing one ?

John

Please Log in or Create an account to join the conversation.

More
07 Sep 2008 20:08 #51803 by lorian
Replied by lorian on topic Which antenna socket ?
I always used to have my one horizontal and one vertical, this was quite effective.

Assuming your 2800 is out of warranty it's only a couple of screws to take a look at the wiring, and you can always remove the heat-retaining foam block at the same time.

Please Log in or Create an account to join the conversation.

  • livingj2
  • Topic Author
  • Offline
  • Junior Member
  • Junior Member
More
09 Sep 2008 18:01 #51843 by livingj2
Replied by livingj2 on topic Which antenna socket ?

Lorian wrote: I always used to have my one horizontal and one vertical, this was quite effective.

Assuming your 2800 is out of warranty it's only a couple of screws to take a look at the wiring, and you can always remove the heat-retaining foam block at the same time.



OK - took it to bits for a look.
Inside is a Mini PCi wireless card (Gigabyte GN-WIAG02), which has an Atheros chipset (I believe). The two aerial sockets appear pretty identical, but the right hand one (J7) looks to have "Aux" printed near it. There IS a difference between the two aerial sockets. The Left hand one - looking from the front, next to the system reset button - definitely provides a better signal strength than the right hand. Both work on their own, but the left is the preferred, apparently.

However - I discovered during a bit of digging on Usenet - the diversity algorithm used to select the antenna, based on received signal strength, is rather clunky. It doesn't cope well with two dissimilar antennas. Therefore - when using a high gain antenna, it would seem to be best to remove the other (low gain) one. Summary - high gain in the left, nothing in the right.

Please Log in or Create an account to join the conversation.

More
18 Nov 2008 22:08 #52903 by gracecourt
Replied by gracecourt on topic Which antenna socket ?

livingj2 wrote: There IS a difference between the two aerial sockets. The Left hand one - looking from the front, next to the system reset button - definitely provides a better signal strength than the right hand. Both work on their own, but the left is the preferred, apparently.

However - I discovered during a bit of digging on Usenet - the diversity algorithm used to select the antenna, based on received signal strength, is rather clunky. It doesn't cope well with two dissimilar antennas. Therefore - when using a high gain antenna, it would seem to be best to remove the other (low gain) one. Summary - high gain in the left, nothing in the right.



Thanks for this... now the natural question... does anyone know which aerial socket on the 2820 series should be used for a high-gain aerial? It has three aerials!! :-)

Please Log in or Create an account to join the conversation.

Moderators: Chris, Sami