Hi sorry to hijack this thread as i’m unable to create my own post and this topic hopefully fits with my question.
Can someone explain how Rx works ? I keep reading a higher Dbi antenna will have a higher Rx and be able to hear more than a lower Dbi.
But then I read that an antenna will be inactive when not beaconing and the sent beacon must reach the receiving antenna in full as in make contact with their antenna.
So in my head if there were two targets side by side 4dbi and 10dbi then if the archers was able to shoot long enough he would hit both… and he didnt have the reach he would miss both as they are just inactive targets.
How does Rx work or does it have some kind of drawing power ?
Imagine an antenna in the middle (hole) of a donut. For the 4dbi antenna the donut will be high and have a rellatively small circumference. For a 10dbi antenna the donut will be flat but have a much larger circumference. Both have the same volume (= amount of energy).
If you are further away from the antenna (but at the same level) you will be inside the 10dbi donut but not inside the 4dbi one.
The disadvantage of the 10dbi antenna is that regulations allow a limited amount of transmission power that is measured at a certain distance from the antenna. At the measurement point the power of the 4dbi antenna might be at the limit and at that time the 10dbi antenna will exceed the limit so the transmission power must be dialed back to stay legal resulting in a smaller circumference for transmissions.
Sorry just in case im failing to understand this. Is this description explaining the transmit pattern or is it describing Rx?
The debate we are having is how a 10dbi antenna can witness/hear more than a 4dbi antenna and the usually answer comes down to its Rx.
But most of us believed when the antenna wasn’t sending/beaconing it was inactive and in order for my antenna to witness another beacon their beacon had to reach my antenna in full. Which then makes me wonder where the Rx comes into play as surely it then just comes down to whether or not the sending beacon can reach me or not regardless of what my Rx is.
If you have a transmitter (TX) and two receivers (RX), one RX with an antenna of 10dbi and one with 3dbi, and they both have LOS and same distance from the TX, ones RX level will be 7db greater than the other.
Hi thanks for the further replies i’ve now had a look through the above articles but didnt explain how the witnessing works unless i’ve missed it or not clever enough to understand it.
Even with your latest reply it still doesnt explain how it benefits to be able to see a beacon thats further away if the beacons needs to actually reach/hit the antenna to be counted as a witness ?
If the beacon fails to reach both the 3dbi and the 15 dbi physically and falls short what benefit would it be for the 15 dbi to be able to see it over the 3dbi not being able to see it ?
Unless what you are saying is the the signal doesnt need to actually reach the antenna to be counted as a witness and just being able to see it is all that matters which would make a lot more sense and explain how Rx is beneficial to these RF antennas.
So now the ones level is 7bd greater than the other, now if we increase the distance between the RX with 10db antenna and TX and still have a greater or equal RX level than the one whit a 3db antenna., up to a point.
A = Attenuation
f = frequency
d = distance
This is for free space