I don't know any references on this, but here's a quick few thoughts that I have.Dear,
are you have any ideas about 2band or 3band (or mult-iband) antenna equivalent circuit?
(in transmission line or lumped element)
Is there any source or book about this subject?
The subject says "dual and triple band antenna". Do you want it to have the same S-parameters at 2 frequencies (for a dual band antenna), or do you want it to have the same S-parameters across the whole band, which is an infinite number of different frequencies?thank you
i only want an equivalent circuit with the same S-parameter of the main antenna
An antenna is resonate when it's input impedance is real. An antenna does not have an output port - it's designed to radiate the signal. So drawing a two port object and having S21 being real is nothing to do with resonance.i was drawn the below circuit on ADS for triple resonant frequency, but i dont know it is true or not, because it has triple resonances but in S21 not S11
i was drawn the below circuit on ADS for triple resonant frequency, but i dont know it is true or not, because it has triple resonances but in S21 not S11
View attachment 66448
What is the purpose of this equivalent circuit?
Dear Debora
thanks for useful comments.
suppose I have an antenna and I want to know
1.how dose this antenna radiate?
2.how is the E-field distribution or current density of the radiator?
3.what's the antenna resonate frequency?
Are these purpose sufficient to knowing the equivalent circuit of an antenna?
And in addition of above reason what's the importance of an equivalent circuit of an antenna of your view?
I'm really appreciate you if you explain more.
thanks
Dear Deborah
Thanks for your complete and useful comments
I found in fact something in the antenna designing that by controlling the near field characterize I can tune the far field distribution.
That's wrong. The antenna can not be resonate if the input impedance is 78 - j 16. By definition of resonance, it occurs when the input impedance is purely resistive. For example, 45 + j0, 1000 +j 0 and 0.1 + j0 are all resonate, but 78 -j 16 Ohms is not resonate.one of the near field feature is the Input impedance .when it is high the antenna radiate well.
for example I calculate the input impedance of an antenna by Smith Chart and it was equal Z(in)=78-j16 in the resonate frequency.
It's a big generalization to say when the input impedance is high, the antenna radiates well. In fact, I know of several designs for antennas which have high directivity, and so would have high gain is the losses were low. But their input impedance is impractically low, making it difficult/impossible to feed them.so I need the equivalent circuit to show me the input impedance of the antenna in a frequency band of 300-600 MHz.and show me it is maximum at the resonate frequency.I know in 402MHz my antenna has the large value of the input impedance and it radiate well.
do you believe that here the equivalent circuit is useless too?
Dear Deborah
Thanks for your complete and useful comments
I found in fact something in the antenna designing that by controlling the near field characterize I can tune the far field distribution.
That's wrong. The antenna can not be resonate if the input impedance is 78 - j 16. By definition of resonance, it occurs when the input impedance is purely resistive. For example, 45 + j0, 1000 +j 0 and 0.1 + j0 are all resonate, but 78 -j 16 Ohms is not resonate.one of the near field feature is the Input impedance .when it is high the antenna radiate well.
for example I calculate the input impedance of an antenna by Smith Chart and it was equal Z(in)=78-j16 in the resonate frequency.
It's a big generalization to say when the input impedance is high, the antenna radiates well. In fact, I know of several designs for antennas which have high directivity, and so would have high gain is the losses were low. But their input impedance is impractically low, making it difficult/impossible to feed them.so I need the equivalent circuit to show me the input impedance of the antenna in a frequency band of 300-600 MHz.and show me it is maximum at the resonate frequency.I know in 402MHz my antenna has the large value of the input impedance and it radiate well.
do you believe that here the equivalent circuit is useless too?
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