Lora RA-01 better range than RA-02? - Page 1
Forum section: electronics / projects

author: panoss
author_rank: Frequent Contributor
timestamp: November 06, 2019, 12:58:15 pm
content: I 've made a Lora pair (Sender & Receiver) using Lora RA-01.It's working with the spring antennas that come with the module.I gave it to a client.Now I 've made a replacement of it, a pair of Loras using Lora RA-02.I 've tried every possible antenna type (spring, whip half length, whip 1/4 length, dipole).Also tried to maximize range with software:Code:LoRa.setSpreadingFactor(12);LoRa.setSignalBandwidth(62.5E3);LoRa.setCodingRate4(8);But I have not managed to get the range of the first pair (which works with the default SpreadingFactor, Bandwidth and CodingRate).I get less than half of the range.How is it possible the spring antenna (which is supposed to be crappy) on RA-01 to perform so much better than any other antenna I 've tried on RA-02?(or maybe it 's not the antenna but something else?)

author: Apollyon25_
author_rank: Regular Contributor
timestamp: November 06, 2019, 11:00:47 pm
content: A quick google image search shows the RA-02 has a small coaxial connector fitted, which the RA-01 doesn't have.So probably the RF path is output to the connector instead of the PCB solder pad of the 'module'.FYI - Pictures and schematics help others to spot your errors/problems.

author: Dave_PT
author_rank: Frequent Contributor
timestamp: November 07, 2019, 10:23:16 am
content: @Apollyon25_ is right.For example, this adapter board has no antenna connection. You really need to use the u.Fl connector to connect to your antenna.

author: panoss
author_rank: Frequent Contributor
timestamp: November 07, 2019, 03:18:30 pm
content: Yes, I know, at RA-02 I am using a connector with a coaxial cable attached to it. I should have mentioned it.

author: Apollyon25_
author_rank: Regular Contributor
timestamp: November 08, 2019, 12:48:21 am
content: Where/what is your antenna?The connector is a 50ohms connection, however your coil antenna version on the RA-01 probably has a matching network to impedance match the antenna (not 50ohms) to the LoRa transceiver output, which is 50ohms.Again, google image search shows this -https://mikroelectron.com/Product/10KM-433M-LORA-LONG-RANGE-WIRELESS-MODULE-RA-01(third image has three components arranged as a U which are most likely the matching network)

author: panoss
author_rank: Frequent Contributor
timestamp: November 08, 2019, 01:14:27 pm
content: Apollyon25_, this is the image you 're talking about?So, what should I do to improve range?

author: Apollyon25_
author_rank: Regular Contributor
timestamp: November 21, 2019, 12:02:15 am
content: If you get good range with the RA-01 and a coil antenna attached to pin 1 (directly/somewhat indirectly in the image shown) then you can simply replicate the parts on your RA-02 board and performance should be comparable. Just trace the connections to find the matching components. Most of these modules have published schematics somewhere so you can probably get values from this.To tune/match antennas you need a VNA - I use the Mini Radio Solutions TinyVNA. Plenty of online resources for how to do the matching.For the RA-02, it's most likely a 50ohm system, so if you connect a IPX to SMA cable (which is 50ohms), and then a suitable frequency range 50ohm antenna (with SMA obviously), you'd get comparable range.So either use a suitable antenna that's already 50R for your frequency band, or you need to add matching.

author: splin
author_rank: Frequent Contributor
timestamp: November 21, 2019, 02:13:12 am
content: Quote from: Apollyon25_ on November 21, 2019, 12:02:15 amBe aware that some cheap antennae are hopelessly out of spec - Andreas Spiess has measured a few which were way out of tune which is difficult to determine without a VNA. Here's one example at 12:25:As to antenna matching and connectors on radio modules you might want to watch another of his videos, particularly starting at 10:33: