If Pr is 0, I think your equation would give you 0 for Pt always.
Consider this Pr is unknown but all the other components are known...i want to know what power an antenna will transmit by rearranging the formula Pr .....and Pr at this stage is of no importance only when i find what my antenna is transmitting using the other components will Pr be important for finding what the power i've received
Consider this Pr is unknown but all the other components are known...i want to know what power an antenna will transmit by rearranging the formula Pr .....and Pr at this stage is of no importance only when i find what my antenna is transmitting using the other components will Pr be important for finding what the power i've received
so its 0 and i omitted it from the Pt equation
Setting a parameter to 0 is not the same as saying it's unknown - in fact it's saying that you know its value is 0! Alpha Dude is correct, if you set Pr to 0, Pt will also be 0. If Pr is unknown, then you can only find Pt as a function of Pr.
Setting a parameter to 0 is not the same as saying it's unknown - in fact it's saying that you know its value is 0! Alpha Dude is correct, if you set Pr to 0, Pt will also be 0. If Pr is unknown, then you can only find Pt as a function of Pr.
i made the mistake of thinking that unknown equates to 0
i made the mistake of thinking that unknown equates to 0
OK, so if Pr is unknown, you can write down Pt in terms of Pr. Are you being asked to evaluate Pt or just find an expression? If you have to evaluate, perhaps they have given you some more information to help you find Pr, or you can make a good approximation.
OK, so if Pr is unknown, you can write down Pt in terms of Pr. Are you being asked to evaluate Pt or just find an expression? If you have to evaluate, perhaps they have given you some more information to help you find Pr, or you can make a good approximation.
I have to design a yagi-uda antenna...i've calculated the gain, wavelength(lambda) and i was given the distance (d)...using lambda i constructed the spacings between the elements on the yagi uda and so by using the Pt formula i want to know what sort of power will i be transmitting using the components given to me already
I have to design a yagi-uda antenna...i've calculated the gain, wavelength(lambda) and i was given the distance (d)...using lambda i constructed the spacings between the elements on the yagi uda and so by using the Pt formula i want to know what sort of power will i be transmitting using the components given to me already
Can you measure the power received? I'm afraid I know very little about yagi-uda antennae...
Pr = (1.9378 . 14.52^2 . 61^2)/(16 . pi^2 . 23^2) = 18.1981 (4dp) <- much bigger than your answer
Is that correct?
its wayyyy too big i cannot receive more power than i transmitted this never has been achieved in science
try to calculate one component at a time for example write 16 .pi = 50.2 ^2 =2526.61 and note it down somewhere and so on until you get all the component values this way then multipy them just like in the equation and then divide the top by the bottom
I get the bottom half of the fraction to be 83536.3317...is the formula meant to be (16.pi)^2 or 16.(pi^2)? I did the latter (which is what your formula implied).
I get the bottom half of the fraction to be 83536.3317...is the formula meant to be (16.pi)^2 or 16.(pi^2)? I did the latter (which is what your formula implied).
in the course notes it says 16π2 i think i made a mistake instead of (16.pi)^2 it should be 16.(pi^2)
i calculated Pt correcting the 16 pi squared issue and i got :
pt = 0.11 watts two d.p
and
pr = 0.10 watts to two d.p
which means my antenna has a loss of 0.01 i think ? which is absolutely sweet...the antenna looks efficient according to the calculations
cheers nathan for clearing things up!!!!!
Last edited by Cabdullahi; 01-15-2010 at 02:22 AM.
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