Hi particle community,
A couple of days ago I acquired an Argon, I was very happy with its operation, I am amazed at the coverage it has with the flexible WIFI antenna but for the project I must carry out I need a greater range, so I bought a pair of 2.4Ghz antennas ( 50 ohms) of 3dbi and 8dbi (https://pcel.com/TP-LINK-TL-ANT2408CL-Antena-Omnidirectional-TP-Link-2-4GHz-8dBi-96796), but today perform a test (wifi scan - RSSI) and the results were disastrous, the signal strength passed from RSSI = -30 to RSSI = -40. I do not understand why this happens, does anyone have an idea? Should I do any extra configuration to use the 8dbi antenna?
You need to activate the use of the external antenna by calling the following routine:
void selectExternalMeshAntenna()
{
#if (PLATFORM_ID == PLATFORM_ARGON)
digitalWrite(ANTSW1, 1);
digitalWrite(ANTSW2, 0);
#elif (PLATFORM_ID == PLATFORM_BORON)
digitalWrite(ANTSW1, 0);
#elif (PLATFORM_ID == PLATFORM_XENON)
digitalWrite(ANTSW1, 0);
digitalWrite(ANTSW2, 1);
#endif
}
Have you tried to orientate the antenna differently?
WiFi signals get attenuated by all sorts of things - including humans - so moving around or between the AP and the device could easily reduce the signal by -10dB.
Are you sure this function is for Wi-Fi connection? I think that function only works for the antenna of the mesh (Bluetooth), if I am wrong please correct me.
I reiterate that the loss of intensity (rssi) occurs when switching to the original Particle Argon (External) antenna with an 8dbi antenna that I buy, which is why I expected to obtain an intensity rssi = -20 or even better than that. I have oriented it to different directions without getting good results
Where are you measuring the RSSI?
RSSI is a two way street. It needs to be measured both at the Argon and the router. If you’re measuring on the Argon, that means you’re measuring the tx power of your router.
Even an omnidirectional antenna is highly directional. Yes, when vertical, it looks ok, but if you turn it horizontal, it actually becomes more directional!
(left side is when the antenna is up and down, right side is when it’s laid horizontal)
How is the antenna being held vertical? If you’re holding it with your hand, you’ll definitely attenuate any signal going in and coming out.
Also, can you explain your test process? (i.e. how you’re comparing the two antennas, etc)
Thank you very much for your answers, this time I will give you more details about my experiment.
First I show you the script that I have uploaded to my Argon, it is very simple. In this I perform a scan of the Wi-Fi networks and print on the serial port the information of the networks (the one that interests me is RSSI).
void setup() {
Serial.begin(115200);
waitFor(Serial.isConnected, 30000);
WiFiAccessPoint aps[20];
int found = WiFi.scan(aps, 20);
for (int i=0; i<found; i++) {
WiFiAccessPoint& ap = aps[i];
Serial.print("SSID: ");
Serial.println(ap.ssid);
Serial.print("Security: ");
Serial.println(ap.security);
Serial.print("Channel: ");
Serial.println(ap.channel);
Serial.print("RSSI: ");
Serial.println(ap.rssi);
}
}
void loop() {
}
The experiment is just as easy, just change the flexible Particle antenna for another 8dbi antenna, and check the results on the serial monitor. The arrangement of the antennas and their results are shown in the following images.
PARTICLE ANTENNA
MY ANTENNA (8dbi)
RESULTS PARTICLE ANTENNA
RESULTS 8dbi ANTENNA
when you say: “If you’re measuring on the Argon, that means you’re measuring the tx power of your router”, I don’t understand why then when I measure the RSSI of the “VELASQUEZ” NETWORK, the small particle antenna has a better result .
I have very little knowledge in antennas, so I thought that with an 8dbi antenna I would improve rssi, but the opposite happens, any idea why this happens? If the RSSI is not a good comparison parameter between these antennas, how could I measure the difference in performance between these two antennas?
Sorry - thinking about mesh and BLE antenna rather than the WiFi antenna off the ESP32.
How far away are you from the AP?
If you put the antenna on your AP next to the WiFi antenna from the Argon and wrap in a shield grounded to the AP then you might get a signal reported like -10dB or more. Once there is anything else around (Bluetooth and Mesh devices, etc. that operate on 2.4GHz) and an air gap then this impacts the measured RSSI.
Your simple WiFi scan isn’t that helpful as the signal is very dynamic - I would measure it every 5 or 10 seconds and either send this an an event or output to Serial as you are now and then see what it looks like. You could then change the orientatation of the 8dB antenna and see if you can achieve a better signal strength. The likelihood is that your 8dB antenna is actually not that good and less effective than the PCB antenna!
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Not quite. 8dbi refers typically to the gain of the transmission. The RSSI that you're measuring is the strength of the signal from the access point. I bet you, that if you were to open the admin panel on your AP and compared RSSI from the Argon you'd likely see a difference. Though I don't have the gain of the included antenna handy. (I think it's a 2-ish dbi? Probably wrong.)
This is a hard test to do and additionally hard to quantify mostly because your environment is not controlled.
- There are other access points near by. That means that there is wifi traffic and potential interference making your test results inconsistent.
- Your antennas are not kept in a known good position. I've done similar tests where I simply move the antenna a little bit and saw HUGE changes in RSSI. As I alluded in my earlier post, despite being "omnidirectional", they're not truly "omnidirectional"
When antennas + devices are measured for performance, they're typically put in advanced anechoic chambers. Something like this:
The antenna in the middle there is a horn antenna they usually use for the measurements.
These chambers are completely sealed from the outside world. They're also made to absorb RF energy. Otherwise the signals would bounce around the metal box and not give enough useful information.
Sooo, long story short, unless you can get to a quiet environment and control your antenna positions well, you're going to get varying results. That's just the name of the game, especially with 2.4GHz.
As a friend of mine said one time "You're a big bag of water and you like to absorb 2.4Ghz!" i.e. you're likely affecting your wifi signals more than you think as well.
Overall, I'm not surprised at the readings you're getting. I encourage you to play around with different positions and see how things change. Also read the RSSI on your access point if you can. You need to look at both the RSSI value on the Argon and on your AP..
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