19-02-2015, 10:09
Basically, gain is how much an antenna can transform RF into electrical signal.
The higher the value, the best.
Imagine that a receiver is only capable of receiving signals better than -50 dBm and the signal to receive isn't that "good", putting an antenna with a better gain, could make the difference and kind of "amplifying the signal" making it enable to be heard.
The receivers that we use in the weather station (superheterodyne), claims to have a sensitivity of -105 dBm, if this value is accurate, you won't need a very complicated antenna in the major of installations because the distance/obstacles probably won't be that much, although, UHF communications (433Mhz belongs to UHF), is made in line of sight basis.
The higher the value, the best.
Imagine that a receiver is only capable of receiving signals better than -50 dBm and the signal to receive isn't that "good", putting an antenna with a better gain, could make the difference and kind of "amplifying the signal" making it enable to be heard.
The receivers that we use in the weather station (superheterodyne), claims to have a sensitivity of -105 dBm, if this value is accurate, you won't need a very complicated antenna in the major of installations because the distance/obstacles probably won't be that much, although, UHF communications (433Mhz belongs to UHF), is made in line of sight basis.
(18-02-2015, 20:50)hvalentim Wrote:(14-02-2015, 10:33)meteoestarreja Wrote: (...) you could try to find a mono band antenna just for uhf, you will get a shorter antenna
(...) in amateur bands when 430Mhz it's referenced, it means that the antenna will work at least from 430 to 440 Mhz
(...) pay attention to antenna's connector, avoid different connector because as more adapters you use, the higher is gonna be the loss...
Thanks for the tips. I am now trying to figure in more detail how "gain" works with antennas.