antennaarduinogainRF
Some radars have thousands of antennas, there are also some routers that have multiple antenna systems.
But I want to know how to calculate total gain of multiple antennas in a system? Is it simply equal to the number of antennas times gain of one antenna?
What about beamwidth of the resulting system? If for example I use 64 antennas in a system, all are omni directional, is the total system still omni?
A dielectric antenna might fit the bill.
It might be a bit hard to home-brew one, though.
Here is Toko, who make a line for GPS.
An antenna has a gain set by its construction. For instance, a simple wire forming a dipole will have a gain of about 2dB whereas a dish might have a gain of 20dB. The lower the antenna gain the less directional will be the transmitted electromagnetic wave. Higher gain antennas such as dishes have to be pointed in the correct direction for them to be effective but, give you a bigger signal when receiving or concentrate the power output more when transmitting.
You can't affect antenna gain by adding an amplifier.
if "for example" the Tx has a power of 20 dBm , antenna has a gain of 10 dBi & antenna amplifier "repeater" has a gain of 60 dB "like common cellular repeaters" , what does this gain mean ? is it mean the antenna gain will be 10+60=70 dBi ? or it mean the Tx power will be 20+60=80 dBm ? I am confused !
another example for Rx antenna , if we have receiver has a sensitivity of -114 dBm and Rx antenna has a gain of 10 dBi & we connect it with 40 dB amplifier , should it mean the total sensetivity will be -114-10-40= -164 dBm ?"ignoring SNR please"
It's impossible to ignore SNR - if a receiver has an input sensitivity of -114dBm then pre-amplifying the signal by 40dB will likely increase noise and signal together and this will mean exactly the same SNR and no net benefit.
if we use Tx has a power of -30 dBm at 1000 m, antenna has a gain of 10 dBi & at 1000 m distance there is a repeater has a gain of 60 dB , how to calculate the total gain at this situation ?
You need to draw a sketch of something here - where is the final receiver (and I don't mean the repeater). Maybe something like this but with ALL the information on: -
Best Answer
I've never heard of radars using thousands of antennas before but the reasons for antenna diversity is well known. Several antennas can increase the probability that, no-matter what direction a transmission is arriving, and no-matter how that transmission is polarized, it will be received correctly.
This usually means, for each antenna, an amplifier and demodulator i.e. it can be quite complex and there is no apparent multiplication of antenna gain. In fact, depending on the mechanical configuration of the antenns, there can be a reduction in gain for each antenna due to the proximity of the other antennas.