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Hi,

just wanted to share the results of measuring the performance of the 5 different antennas working on 433MHz, dedicated for my LRS.

The LRS I test, is my own variation of OpenLRSng, where the key is to have the ability of controlling the plane and receiving the data from the plane (from it's APM + receiver status) using the same link.

I'm focused now on the HW part of the project and I'm investigating the 5 different antennas:

Antennas 1 and 2, sold on eBay as the simple helical 433MHz, number 3 sold as improved range 433MHz antenna. Number 4 it's Diamond RH771, duo bander antenna from professional UHF Alinco radio I own. The last one is the simple half wave dipole which I made using the bowden cable.

The test procedure was:

- the power output for TX and RX is limited and constant across the test,

- I put the receiver in one room of my house, RX has the helical antenna similar to number 1 from the picture,

- RX waits for the signal from TX, once the signal is received RX sends back the message to TX with the information of it's RSSI,

- I embedded the TX into my Taranis Plus - it logs the RSSI of TX (which means how strong is the RX signal - received by TX) and RSSI of RX (means how strong is the TX signal - received by RX),

- I put the certain antenna into TX, switch on the radio and walk around my garden and the house with the antenna in vertical position (pointed up), 1m above the ground,

- this way in some areas I have a couple of walls between TX/RX and the distance from 1 - 100m,

- I started with the antenna 1, then 2,3,4,5 and antenna number 1 - again - to see if any changes appears across the time of measurements,

- at the end I have the one clear log for each 5 antennas recorded by Taranis with the values of the RSSI in TX and RX as SI4432 measures it.

Here is the log:

PM_Simulator-2016-04-24.csv

With RX green signal, whenever the value is 0, that means the signal from RX was missing in the required time window, so it's a kind of pre-failsafe.

I was quite sure that Diamond shall be better than eBay antennas, but I'm quite surprised in the positive way that the dipole I did in 20minutes from the spare parts is better than much more expensive Diamond antenna.

The ground side of the dipole (with the green part) is made out of the flex wire, so it will survive the landing of the plane while this part is below the plane's fuselage.

The next step is to test the VEE antenna by IBCrazy and mount my link into the plane to see the performance in the air.

Jacek Szostak