Antenna length for 868 and 433 MHz

End Devices (Nodes) Hardware
22

And even if you make the perfect match and squeeze the last few tenths of a dB out of the performance, you will see that in practical use of the device, the proximity of other materials to the device makes such a noticeable effect on your antenna characteristics that all your perfectionist efforts were pretty much useless :smiley:

23

I’m sorry my response took this long. Must have overlooked your question. Antenna lengths give better reception the closer to the wavelength the antennalength is. 1/2, 1/4, 1/8 and 1/16th lengths do work. 17.31 cm divided by half is 8.66 cm. 8.8 seems a bit long, about 1.6% too long. That might answer the shorter range. Could also be this is just a flunk antenna: it happens that antenna’s are just defective.

I would experiment with two pieces of 8.66 and 8.8 cm wires, see how the reception turns out. That rules out any defect in the stock 8.8 cm antenna.

24

Thaks a lot for all your useful and informative comments. I have tested different antennas provided with my other shields, SX1276MB1MAS. However, I get the same results which are a too short range (500 m for 868 MHz)!
There is a point about the output power that I see from two LoRa modules (SX1276MB1MAS and SX1276MB1LAS) according to the following links:
https://www.digikey.com/products/en?keywords=sx1276MB1LAS
https://www.digikey.com/products/en?keywords=sx1276MB1MAS

I understand that LAS type is equipped with a power amplifier providing a 20 dBm output power where MAS type (with just 14 dBm output power) is not.
Do you think this might be a reason to not achieve a longer range than 500 m for MAS type LoRa shield?

Thanks again,
Mehrdad

25

Depends if 500M is about right for the environement and antennas , but you would expect more even in an urban environment.

The power increase between 14dBm and 20dBm is 6dBm and this represents a doubling of range\distance.

26

Yes. Actually, it was 500 m TX/RX line of sight and this is something that you can simply achieve with other wireless modules like Zigbee. I am now stopped at this point and cannot continue to develop the projects with this unbelievable short range from LoRa (Low Powe, Long Range 
).
I know that LoRaWan can help to cover the longer areas. However, I need to make sure if I have received to the maximum possible with this SX1276MB1MAS first.
I wonder if anybody has achieved to the longer node-to-node ranges and how?

27

Its not LoRa that is the issue, something with your setup, code or devices.

Significantly reduced range is a symptom of damaged LoRa modules and\or in the case of the SX1276MB1MAS a problem with the antenna switch itself or not driving the switch correctly in software, as mentioned elsewhere.

1 Like
28

I have done 40km LOS on simple 1/4 wave wire antennas for RX and TX, 434Mhz, BW62500, SF8, 3mW. standard hardware, basic software. Expect half that range at 868Mhz.

29

Wow. This is really perfect!!!
I have tested several devices and all are the same in my case. Then, as you mentioned, it might be ‘not driving the switch correctly in software’. In a very simple case, I use two simple TX/RX examples (SX_01a_TX_LoRa and SX_01a_RX_LoRa) and SX1272 library. I have tested several alternatives. My pure setting for 868 MHz is here:
sx1272.ON();
e = sx1272.setMode(4);
e = sx1272.setHeaderON();
e = sx1272.setChannel(CH_10_868);
e = sx1272.setCRC_ON();
e = sx1272.setPower(‘M’);
e = sx1272.setNodeAddress(3);

I use the following command to transmit a packet (message) to the node no. 8:
e = sx1272.sendPacketTimeout(8,message,50);
and this for receiving the packet in a for loop:
for (unsigned int i = 0; i < sx1272.packet_received.length; i++)
{
my_packet[i] = sx1272.packet_received.data[i];
Serial.println( my_packet[i]);
}

I wonder if it would be possible for you to kindly provide me a link to the library (.h and .cpp file) you have used and the setting for the SX1276 that you have successfully used?
If it is hard to write it here, my email is mehrdad_babazadeh@yahoo.com

Thanks a lot again,

1 Like
30

Your problems seem to have no relevance to antenna length or problems with the things network.

1 Like
31

Thanks anyway. It is still a problem and I have to look for any solution or somebody who can help.

Best wishes.

32

Hurts Eyes :wink:

1 Like
33

Correction:
I had forgotten the 869.525 MHz frequency used for the RX2 downlink:

868 MHz band LoRaWAN frequencies range from 867.100 MHz to 869.525 MHz with middle frequency 868.3125 MHz. The optimal LoRaWAN antenna length would thus be (velocity factor not included):

299,792,458 / 868,312,500 = 0.3452587 m for full wave length (1λ) antenna
0,1726294 m for half wave length (œλ) antenna
0,0863147 m for quarter wave length (Œλ) antenna

In practice this still makes too little difference (with using 868.0 MHz for the calculation) to be significant.

1 Like
34

Did you check your software and library what settings it is actually sending to the sx1272? You might be setting the bandwidth wrong, you might be setting the output power wrong, you might be selecting the power boost the wrong way, you might be inadvertently activating the current limiting, you might be setting the ramp-up wrong, etc, etc. I’ve had my share of ‘pulling out my hair’ moments with -in my case- the RFM95, but in the end, it all makes sense and you just have to get acquainted to the documentation.
Best thing to do, hook up a logic analyzer to the communication between processor and sx1272, select proper decoder and check what configuration commands are actually sent to the module. This is much easier than it sounds.

35

hello sir we trying to build a lora network for our project with lora nodes from Microchip - RN2483 , 868mHz frequency. we are using the following antenna dimensions , tried with both 50 mm and 108 mm , the range maximum we could attain in just few meter, with line of sight. could you guide us how can we attain max distance

36

The lengths normaly used for antennas are 1/4 the wavelength or 8.6cm for 868Mhz, although in practice maybe up to 1cm shorter.

So why your using 5cm or 10.8cm I cannot understand.

When you say a ‘few meter’ what does that actually mean ?

1 Like
37

thank you for respond sir,actually our antenna height is 10.796cm(big) and small antenna height is 5.1cm. when we testing with those antenna for lora nodes communication we are getting up to 20meters only but we need up to 500meters then what to do.

38
  • what type of gateway do you use
  • what node do you use
  • what node software do you use
39

Whilst the antenna lengths do not seem to be optimum, they would still provide way more than 20m range, even at the highest of the LoRa data rates.

Those are the ranges you could expect with ‘line of sight’ when there are no antennas connected at all, so are you using a LoRa device that expects you to independantly setup the antenna switching between transmit and receive ?

Edit: On checking I see you are using the RN2483, are you connecting the antenna to the correct port on the RN2483 ?

40

1.what type of gateway do you use: right now we are not using any gateway,through node to node communication we are trying.we done in communication between two nodes but we are trying for long distance.
2.what node do you use: RN2483(microchip).
3.what node software do you use: we are using tera terminal for peer to peer communication

41

we are using antenna in correct port.please send me a document or link for long distance communication(node to node)