Is the radiating angle of phased.Radiator specifies the beam boresight angle ? What if the weights in phased.Radiator speifies weights to point beam to some other direction ? Can we see the output pattern of the phased.Radiator ?

With reference to scan radar example in phased array tool box

http://www.mathworks.com/help/phased/examples/scan-radar-using-a-uniform-rectangular-array.html

If we wish to steer the beam as defined by the weights, why do we need to specify the target angle in pahsed.radiator ?

Answer 1

[Honglei Chen]

You are right that the weights determines the steered beam direction, but the signal arrives at the target may not always come from the mainbeam. Therefore, if you want to compute the signal transmitted to the target when the beam is steered, you still need to specify the target angle.

Hope this clarifies you question.

[Raza Umar]

Thanks Honglei for your prompt response. I agree with your point but may be I dont know how to visualize it in Matlab.

1. For example, lets assume the target to be at boresight, i.e. radiating angle is 0 degrees and my main beam is also steered to 0 degrees. Looking at the radiation pattern,I can see that my array gives a 30 dBi gain at boresight. How to verify this that the signal transmitted to target is really scaled up by 30 dBi ? Actually, what I observe is that the signal power is added by the factor given by 20*log10(Ne), where Ne is the number of elements in the array. This is happening may be due to selecting the combineRadiated signal property of radiator to be true... But my concern is where is the influence of radiation pattern in this scale factor... how to observe the 30 dBi gain that was expected in the the signal transmitted to target ?

[Raza Umar]

Also another short query? If the input sample to array has power say 1W,does the power of the radiated signal from the array with Ne elements and G dBi gain, would be Ne Watts? and my EIRP would be 10*log10(Ne)+G dBW ??? Am I right ?

[Honglei Chen]

Hi Raza,

Sorry I just saw this. The factor you see as 20*log10(Ne) is in dB, not dBi. When you use a radiator, it simply adds the field together at the desired direction. Whether it's dB or dBi, the shape is the same. To see the power relation in dBi, it's necessary to setup the problem in some sort of power relation. For example, if you assume the input has a power of 1, then not all those powers are radiated toward the target direction. How much of that power gets radiated toward the target actually depends on the array's radiation pattern. If you go through that process, you'll be able to verify the dBi value. Does this clarify your concern? If not, please feel free to shoot me an email so I can respond to you promptly. Thanks.

[Raza Umar]

I understand your point but unable to verify the dBi value, can you please provide a minimal working example to elaborate your point, please ?

[Raza Umar]

I was expecting that the amount of power that gets radiated towards the target, should be in accordance to what value the plotResponse reads when draws in "dBi" scale but I am observing that it actually corresonds to what the plotResponse reads at "dB" scale.... Thats the confusion !!! since its Gt (dBi) in FRISS equation which is being modelled not the power pattern in (dB) ???? Can you please guide if the Matlab considers the powerpatter in dB to be the gain ????