The BIG and SMALL ANTENNA topic part 1


(Remko) #103

Yesterday at the TTN Apeldoorn meetup I tested the nice black 868 MHz antenna which was purchased in China.

I found that the performance of this antenna is very poor.

Measurement0206 - CE

The antenna (?) was not resonant at 868 MHz although the spec says :slight_smile:
Also the return loss is not good.

It is another proof that not all “antennas” are really a antenna.


#104

looks more like a dummyload :open_mouth:

funny thing is… I did not measure this antenna, just connected it to a node and got really good results.


(Remko) #105

I found that measuring antennas and link performance with LoRa nodes and gateway is close proximity, is very difficult.
I have a node with a dummy on my table that at SF12 is picked up by a gateway 3 kilometres away.
for isolating nodes I created a small farady cage.


#106

yes but I tested with my own gateway switched off and could reach a GW more then 10 KM away.
ok it was not real measurement just a quick test.


combined LoRa / GPS / GSM … uhhhhhhh


(Remko) #107

Seems aproperiate :+1:


#108

I think that has more to do with the antenna of the gateway :slight_smile: .

I also think bad antennas just ‘still work’, and that LoRa is just so good at retrieving the signal from all the noise. E.g. on a good day I can get around 12km range between my gateway with @lex_ph2lb DIY GPA antenna and a rubber ducky from Aliexpress on my node. The GPA has no gain and the rubber ducky probably only has loss, and is also probably meant for 900MHz.

Testing with the Sunhans 13dbi and the ‘grey tube’ 10dbi from Aliexpress doesn’t give significantly different results.

I have ordered the CXL 900-3LW-NB/868 MHz and want to do some RSSI testing comparing this one to several Aliexpress antennas, but I haven’t found time to do it yet. Anyone is free to give a helping hand (Ghent region) :blush: .


(Remko) #109

I have this antenna on the Mheen gateway in Apeldoorn: http://www.mars-antennas.com/ma-wo850-5
This antenna is ~ 120 euro ex VAT. in the Netherlands.
I measured this one yesterday:

Measurement0205 - Mars

This antenna will also be installed on the permanent gateway at Kadaster in Apeldoorn.


(Remko) #110

I would do antenna performance measurements without using LoRaWAN but with a setup with RF signal measurement.


#111

Unfortunately I’m no ham and don’t have any RF equipment other than LoRaWAN gateways and nodes.


(Remko) #112

It seems as if we have to organise a antenna measurement session.


#113

good idea !


#114

I’m in. If it’s not too far away :wink: .


(Remko) #115

What would be a good location in your opinion?


#116

Anything in the triangle Brussels - Eindhoven - Amsterdam :smile: .


#117

We are also interested in a session anywhere in this " golden triangle ".


(Mikael Falkvidd) #118

Maybe a session could be held on The Things Conference?


(Remko) #119

For antenna measurements you need some open space without a lot of buildings
That meeting is beginning next year. I think some talks about antennas are possible.


#120

to measure swr and/or on what frequency the antenne is tuned ? I don’t understand
I was thinking… bring your antenna, be it a 10 dbi 'stick or a rubber duck or a DIY GP and this can be measured 'on the spot… am I wrong ?


(Remko) #121

No, you are not wrong. For an indication that will do fine.

I was considering antenna efficiency measurements.

Do we have access to some location preferreably close to public transport (train)
I think we have to expand the triangle to a polygon including Utrecht :slight_smile: .

Who can offer such a place?


#122

3 dbi test :sunglasses: