LoPy Antenna Setup / Installation



  • Hi,

    I received my LoPy just recently and would like to play with it.

    But I haven't received any documentation. I read https://docs.pycom.io/lopy/lopy/general.html but there is no section on how to install an external antenna. Is it mandatory or not? Only Lora external antenna mandatory? How can I switch from the Wifi internal antenna to the external antenna? Just plug the pigtail cable onto the LoPy module or are further steps need?

    From "other devices" I know that setting up the RF-part is important. If someone powers up this device without installing an antenna, the RF-part could be destroyed!

    Please write something about the antenna installation...

    Regards,

    Andreas



  • @assia said in LoPy Antenna Setup / Installation:

    it will be automatic as soon as I set up the external antenna

    Yes, you do not need to do anything more
    and as written previously better is not start Lora without antenna at all



  • @livius thanks for quick response. Unfortunately I did not know that. So i don't need a configuration code to select external antenna and it will be automatic as soon as I set up the external antenna?



  • @assia
    Lora must use external antenna it does not use smd antenna
    it is only available for Wifi

    It is strongly recomended to do not use Lora without Lora antenna at all.

    And because of that, you do not find any settings for this in documentation
    it work only with external antenna



  • Hi @LoneTech I used lopy in LoRa mode without external antenna and now I have to add the external antenna and I want to know if I have to do a configuration in my code to select the external antenna.
    Knowing that I found nothing in the documentation as for WLAN for example.



  • @GregS A pleasure ;)

    Moreover, I forgot. Even when not causing damage, overheating might cause signal distortion, which can be a tough issue to debug. I'm speaking in general terms once more, but better safe than pulling your hair out because suddenly you can't decode your transmissions properly.



  • @borjam Hmm - thanks for the heads up re the 1% duty cycle @20dBm - I guess that's an added incentive for honouring network fair use policies. ;^)



  • @bmarkus

    Anyway the SX1272 datasheet states a maxium VSWR of 3:1 when transmitting at +20 dBm. (rev. 3, page 84) and a maximum duty cycle of 1%. In extreme cases it could lead to damage I imagine.



  • @borjam said in LoPy Antenna Setup / Installation:

    @SakshamaGhoslya

    Some wireless hardware can suffer damage when transmitting without a proper termination impedance. Also, it's possible to suffer some unexpected interference in other parts of the circuit due to stray RF.

    For instance, a coworker had problems with a router last month. Its GbE port wouldn't work at 1 Gbps. It turned out the culprit was a 5 GHz wireless interface which didn't have an antenna connected. It wasn't being used but it wasn't disabled either, and its default transmission power was 30 dBm (1 W).

    Although you won't likely damage the LoPy by operating it without an antenna. As a general rule, always keep healthy habits when dealing with RF equipment. So, use an antenna or a 50 ohm terminator It will never hurt, and you will make sure that your test results are reproducible. And you will avoid paranormal phenomena.

    If you have overload problems try separating the units a couple of meters, use an attenuator and/or lower transmission power.

    While you are right in general, my answer was specific to SX127x.



  • @SakshamaGhoslya

    Some wireless hardware can suffer damage when transmitting without a proper termination impedance. Also, it's possible to suffer some unexpected interference in other parts of the circuit due to stray RF.

    For instance, a coworker had problems with a router last month. Its GbE port wouldn't work at 1 Gbps. It turned out the culprit was a 5 GHz wireless interface which didn't have an antenna connected. It wasn't being used but it wasn't disabled either, and its default transmission power was 30 dBm (1 W).

    Although you won't likely damage the LoPy by operating it without an antenna. As a general rule, always keep healthy habits when dealing with RF equipment. So, use an antenna or a 50 ohm terminator It will never hurt, and you will make sure that your test results are reproducible. And you will avoid paranormal phenomena.

    If you have overload problems try separating the units a couple of meters, use an attenuator and/or lower transmission power.

    Regarding damage: when a radio transmitter is not properly terminated, part of the transmitted energy is "reflected" towards the transmitting circuit instead of being absorbed and radiated by the antenna. If the reflected energy is too much it can really damage the transmitter. As a minimum it can cause overheating.

    I insist: even if the transmitter won't be damaged, develop the habit of keeping the holes plugged.



  • @livius said in LoPy Antenna Setup / Installation:

    @bmarkus
    this was on Pycom documentation - i do not remember the exact place

    And it is my personal experience working with Lora devices and gateways :)



  • @bmarkus
    this was on Pycom documentation - i do not remember the exact place



  • @livius said in LoPy Antenna Setup / Installation:

    @SakshamaGhoslya
    Starting without an antenna may damage the hardware

    Regarding the LoRa part (SX127x), transmitting w/o antenna will not damage the device. Even it is necessary to use it w/o antenna if you are experimenting two LoRa devices close to each other to avoid loss packets, overriding receivers.



  • @SakshamaGhoslya
    Starting without an antenna may damage the hardware



  • @borjam "Using the LoPy hardware without antenna can harm"
    Can you please elaborate it little bit?
    What kind of signals can harm the hardware?
    How will they harm it?



  • @borjam @LoneTech Thanx :-)



  • @rskoniec That should be fine. You can shut the LoRa radio down with network.LoRa(power_mode=network.LoRa.SLEEP), but it should be OK to just not transmit.



  • @rskoniec said in LoPy Antenna Setup / Installation:

    Just wondering - what if I'm not using network.LoRa in my project - connected LoRa antenna requirement is still an issue?

    It won't transmit if you don't use it, so it shouldn't be an issue. Still, it is good practice to always "keep holes properly plugged" ;)

    Just a healthy habit.



  • Just wondering - what if I'm not using network.LoRa in my project - connected LoRa antenna requirement is still an issue?



  • @te-bachi RF stuff requires some care. So I would recommend you to always install a proper antenna. Some transmitters can be damaged without one, or some circuits can misbehave due to interference. At the end of the day, the way to avoid unpleasant accidents and paranormal phenomena is to keep the simple rule: antenna always connected.

    If you don't want to install an antenna, use a cheap 50 ohm terminator with a SMA connector. I would tell you to verify that it supports the transmitter power, but 14 or 20 dBm won't be an issue :)

    Hint to Pycom: it would be a good idea to sell an accessory kit with, say, a couple of terminators, a couple of good quality coax cables terminated in SMA connectors and an assortment of attenuators. There are cheap 20, 30 or 60 dB attenuators available nowadays, and in case of doubt it can be really helpful to find out wether interference or bad software is causing problems.


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