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This is part 49 of the LoRa/LoRaWAN tutorial.

In this tutorial I will explain what a Moxon antenna is and how to build one.

The Moxon antenna is a simple and mechanically robust two-element parasitic array antenna created by amateur radio operator Les Moxon.
This directional antenna is equivalent to a two element Yagi-Uda antenna.
It has a reflector and a driven element but no directors.
The two elements are mechanically connected by two insulators.
The antenna has a large beam width and a very good Front-To-Back ratio.

To find the Moxon antenna dimensions you can use the following calculators:
Online calculator:http://tippete.net/cgi-bin/moxgen.pl
Windows program:https://ac6la.com/moxgen1.html

I have used the 4NEC2 antenna modelling software to verify the design.
4NEC2 card deck:https://www.mobilefish.com/download/l...

How well does my self build Moxon antenna performs?
To answer this question, two performance tests will be conducted.
Performance test A:
The Moxon antenna is attached to an end node, which is located inside a building, and transmit messages which will be received by nearby gateways in my area.
In this test I am only interested which gateways were able to receive the transmitted sensor data.
The test will be repeated using a sleeve dipole antenna.

Performance test B:
The Moxon antenna is attached to an end node and transmit messages which will be received by a dedicated gateway 6 meters away.
Both devices are indoors.
The average RSSI is calculated.
The test will be repeated using a ½λ dipole antenna.

Performance test A and B are simple tests and will give me a ROUGH INDICATION how well my antenna performs compared to the dipole antenna.
Both tests are conducted indoors which means the walls reflects the transmitted signals thus influencing the measurements.
Therefore take the results with a grain of salt!
A much better method to tell how your antenna actually performs in the real world, see this procedure:
https://github.com/LoRaTracker/Antenn...

The Moxon antenna performance is compared with a sleeve dipole antenna.
More information about sleeve dipole antennas, see tutorial 43.
For this test I am using the end node and antenna C as demonstrated in tutorial 33.
More information about this end node, see:
https://www.mobilefish.com/developer/...
The end node uses the MCCI LoRaWAN LMIC Library:
https://github.com/mcci-catena/arduin...
The end node uses the following sketch:
https://www.mobilefish.com/download/l...

Performance test A
I have NOT modified the end node transmission power when using the Moxon antenna.
The Moxon antenna is attached to the end node at location A and transmits data.
I have done the same with the sleeve dipole antenna.
In both cases two messages per minute were transmitted.
Both logged data can be found at:
https://www.mobilefish.com/download/l...

One or more gateways were able to receive my transmitted sensor data, see:
https://drive.google.com/open?id=18SK...

Performance test B
Make sure you keep everything in your setup the same when switching from the Moxon antenna to the ½λ dipole antenna.
A slight change can impact your measurements.
- Do not change the height of the end node and the height of the gateway.
- Do not change the distance between end node and the gateway.
- Use the exact same end node and gateway.
- Use the same coax cables and connectors.
- During the measurements I did not stay in the same room.
- The distance between transmitter and receiver should be greater than 4λ (Far field region)

The ½λ dipole antenna used in this setup, see tutorial 41.

The logged data can be found at:
https://www.mobilefish.com/download/l...
In both cases one message per minute were transmitted.
The average RSSI when using the ½λ dipole antenna: -26.5 dBm
The average RSSI when using the Moxon antenna: -22.2 dBm

Conclusion
Based on the average RSSI test results and the results from performance test A, the Moxon antenna performs better compared to the sleeve dipole antenna.
but the Moxon antenna is a directional antenna, you need to point it to the correct direction.
The sleeve dipole antenna is an omnidirectional antenna.

Check out all my other LoRa/LoRaWAN tutorial videos:
   • LoRa/LoRaWAN tutorials  

Subscribe to my YouTube channel:
   / @mobilefish  

The presentation used in this video tutorial can be found at:
https://www.mobilefish.com/developer/...

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