Today i was looking a bit longer on my map and was monitoring a bit the RSSI values shown on the receiver
It is clear that aircraft closer to the receiver normally does have a stronger signal.
But how does the used aircraft or even the airline does have an impact to these values?
I have aircrafts/tracks with obviously stronger signal far away compared to others much closer. And in the opposite closer aircraft with less signal value.
Example from this moment:
The KLM is 150 km away (sorry for switching to km @wiedehopf ), also the NetJets while the Lufthansa is close but with weaker values
Especially aircraft of Ryanair always pop up with strong signal, independent from their distance.
Or is this all just by chance based on the current conditions?
Some people (on this forum) think RF is easy, but this is a simple example showing how fast it gets complex.
Different aircraft have the antennas in different locations. Different manufacturers may have different output RF power. The shape and material of the fuselage will affect to radiation pattern. At certain angles, the engines will obscure under-mounted antennas.
The radiation pattern is unlikely to be (truly) omni-directional, so the (your) RSSI will vary depending on the planes relative bearing.
It’d be interesting to remap the altitude colours to show RSSI to see what is dominant.
As i am not an expert on this topic, i was just curious and would like to get more details about it.
Your post makes sense to me and the pictures are pretty interesting and explain some things to me.
Here is something to think about - if you have a light, slow low flying aircraft, you can punch a hole in the skin and mount a conventional antenna like this
But what do you do if you have a fast, high flying composite aircraft that doesn’t offer a ground plane?
You embed a 2-dimensional antenna in the composite where the antenna isn’t the conductor, but rather the hole in the conductor
Skeleton Slot Antennas are well into the “weird” of RF behaviour.
I was going to use one like that on an alloy plate but at $30US I decided that a piece of brass welding wire was cheaper.
Then I found I could make a CoCo with some gain and moved on.
So as not to be completely off topic I watch aircraft coming and going and B787s particularly are visible about 30NM further away when they are arriving compared to departing.
I categorised 24 hours of data from timelapse1090 according to aircraft type, and took the top 5 most common types:
Boeing 737-800
Airbus A320-232
Airbus A320-251N
Boeing 787-9
Boeing 777
Here is the distribution of signal strengths according to type:
There’s some slight variation, but this doesn’t account for the position of the various aircraft.
Here is the same data binned into 50 mile increments:
Range affects signal strength to a much larger degree than there is any variation between aircraft types. There is some small variation between types but whether there is any significance is questionable since aircraft of the same type could have different avionics fits. It’s also possible that data aggregated over a longer period could provide different results.
Here is the distribution of signal and range of the top two most frequent aircraft for this days data:
), also the NetJets while the Lufthansa is close but with weaker values
