Wireless Shell External Antenna

[vangalvin]

I have been testing the units in close provimity and have not neede an antenna for the 2.4Ghz side. However tonight I decided to do some tests and attached an antenna from a wireless router I had kicking about. I know this is well runed to 2.4Ghz as it was in use.

Well after attaching the antenna the signal level did not change at all. I then grabed another antenna just in case there was an issue with the first. Same result.

I checked all the connectors and confirmed that there are no breaks, the UFL connector is brand new so I am at a bit of a loss as to why adding an external antenna would have no impact on the signal level

Any ideas?

[vangalvin]

Well there’s the problem!!!
There is a solder pad for an antenna, if i connect a peice of wire to that I get -64 to my main wireless router.

With cable attached to the connector with no antenna and no wire attached to the solder pad I get -73

With the cable attached and a small antenna there is no change, -73.

So it would appear that for some reason the UFL connector is not connected. I also tested the other boards and have the same problem.

And just as a comparison I have an ESP32-WROVER with its onboard antenna and that is giving me -63.

and the ESP8268 is giving me -64.

Another interesting thing is that the Wireless Shell is only picking up 1 network with or without the peice of wire. The WROVER and ESP8268 are picking up 3 additional networks.

[vangalvin]

Some tests.
COM5 = Wireless Shell with a known good UFL connector and a 3dBi antenna
COM14 = Wireless Shell with a RP-SMA soldered to the ANT Out pin via a coax cable and a 3dBi antenna connected.
COM11 = ESP32 WROVER with an integrated antenna

Both antennas used on COM5 and COM14 are exactly the same and have been tested.

[vangalvin]

And this is a 10dBi antenna set up on a mount, The antenna was first connected to the COM5 Wireless Shell via the RPSMA on the end of the UFL lead
The log was stopped and antenna was then connected to the RPSMA wired via a coax lead to the Antenna Pad on the COM14 radio.

I am wondering if there is an issue with the matching circut on the UFL inside the Wireless Shell as this would result in an impedance missmatch and a high amount of reflective power essentially causing the receive circutry to go deaf.

Regards
Andrew

[Supporter]

We are discussing your response and will give you a detailed answer this week.

[vangalvin]

Thanks There is still some slight instability in the signal but soldering the lead to the pad has made an improvement. I may grab a couple of ferrite beads to put over the coax as well and see if that helps any as this will dampen some of the reflected power.

The Lora side seems to be working OK although even with antenas tuned to 868 across the desk I am only getting -80’s I would have thought that with such close proiximity it would be well down in the -30 to -50 with them sitting on the same desk. the SNR is around 6 to 8.

Hopefully we can get these all sorted as the first Antartic test is in a few weeks.

[vangalvin]

It would appear that I have a similar issue with one one of the LoRa connectors however I can not solder an external connector to it as there is no colder pad for it.

Testing the first and second unit gives me the following
Testing between Node1 and Node2 with Node3 powered down.

Node1:
07:19:12.962 -> Sending Hello,I’m coming!
07:19:13.716 -> Received from: 0xbb
07:19:13.716 -> Sent to: 0xfd
07:19:13.716 -> Message ID: 22
07:19:13.716 -> Message length: 17
07:19:13.716 -> Message: Hello,I’m coming!
07:19:13.716 -> RSSI: -65
07:19:13.716 -> Snr: 11.25

Node 2:
07:19:10.365 -> Sending Hello,I’m coming!
07:19:13.000 -> Received from: 0xfd
07:19:13.000 -> Sent to: 0xbb
07:19:13.000 -> Message ID: 8
07:19:13.000 -> Message length: 17
07:19:13.000 -> Message: Hello,I’m coming!
07:19:13.000 -> RSSI: -68
07:19:13.000 -> Snr: 5.75

Testing between Node1 and Node3 with node2 powered down.

Node 1:
07:26:56.794 -> Sending Hello,I’m coming!
07:26:58.883 -> Received from: 0xbe
07:26:58.917 -> Sent to: 0xfd
07:26:58.917 -> Message ID: 21
07:26:58.917 -> Message length: 17
07:26:58.917 -> Message: Hello,I’m coming!
07:26:58.917 -> RSSI: -72
07:26:58.917 -> Snr: 11.25

Node 2:
07:27:42.527 -> Sending Hello,I’m coming!
07:27:43.867 -> Received from: 0xfd
07:27:43.867 -> Sent to: 0xbb
07:27:43.867 -> Message ID: 201
07:27:43.902 -> Message length: 17
07:27:43.902 -> Message: Hello,I’m coming!
07:27:43.902 -> RSSI: -119
07:27:43.902 -> Snr: 9.50

And that is with or without the antenna. Just to be sure it was not an antenna issue I also swapped the anttenna with Node 2.

[vangalvin]

And Node 1 connected to Node 4 with the other nodes turned off.

Node 1:
08:43:12.390 -> Received from: 0xbb
08:43:12.390 -> Sent to: 0xfd
08:43:12.390 -> Message ID: 124
08:43:12.390 -> Message length: 17
08:43:12.390 -> Message: Hello,I’m coming!
08:43:12.390 -> RSSI: -47
08:43:12.390 -> Snr: 8.00

Node 4:
08:43:04.681 -> Received from: 0xfd
08:43:04.715 -> Sent to: 0xbb
08:43:04.715 -> Message ID: 118
08:43:04.715 -> Message length: 17
08:43:04.715 -> Message: Hello,I’m coming!
08:43:04.715 -> RSSI: -45
08:43:04.715 -> Snr: 30.00

[Supporter]

Hi @vangalvin

Very sorry for the late reply. We did some tests recently.

WiFi search without antenna:

When I connect such an antenna in the 2.4GHz U.FL socket:

And here is the impendence matching:

I think your problem may be on the hardware, or it may be caused by the difference in product batches… but I can’t determine it now. Anyway, I will resend some samples I have confirmed to you, I hope that will help you find and solve the problem.

[vangalvin]

Thanks for getting back to me. That is definatly more what I would have expected.
With luck it is only a batch issue the dates for the site tests are getting a little too close.