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I don't think it's enough what you call it. A sensor or an antenna has to behave as such for the name it has.
This is actually the reason why I posted in #4 when I said that an antenna cannot be detuned one frequency decade, just because its dielectric changes.
Now, between us, I don't think...
I am confused.
Pictures in post #1 shows very clear that is about a "rubber ducky" helical antenna (the one that you submerge in a Berzelius cup of water).
Post #8 it says that is about a "sensor".
Post #6 it says that is about a "monopole antenna".
Post #9 says that is about a "moisture...
I think there is a confusion between Cross Linear Polarization and Circular Polarization, which are different concepts in the context of electromagnetic wave polarization.
Cross Linear Polarization refers to two orthogonal linear polarization states, when Circular Polarization occurs when the...
I don't name it "normal" but slots placed on the patch antenna could increase the antenna bandwidth, change the resonant frequency, change the antenna polarization, increase antenna efficiency (by reducing surface wave effects), reduce antenna patch size, change the antenna pattern, etc.
Generally the bandwidth of a normal patch antenna (rectangular or circular shape) is about 5%. This is about 175MHz at n78 frequencies.
Frequency range of n78 band is from 3300MHz to 3800MHz (500MHz).
There are many proposals to increase the patch antenna bandwidth.
From my experience the best...
If you read carefully you will see that the original post does not mention the length of the cables, which had to be chosen somehow. And I think it is better to choose them randomly than depending on the wavelength.
As an RF professional, unfortunately, I had very, very bad experiences using...
The impedance mismatches in coaxial cables, theoretically appears only if the coaxial cable is too long or is improperly terminated.
In our case, when using 50 ohms resistors placed in parallel to the input and to the output, the RG58 coax cable is improperly terminated which cause reflections...
A simulation using a short 1m RG58 coax cable, shows that S21=-0.25dB and S11=-25dB.
50 ohms resistors placed either at the input or at the output, degrades S21=-3.8dB and S11=-10dB.
Using a long 20m RG58 without 50 ohms resistors, S21=-4.9dB and S11=-30dB.
The same 20m RG58 coax cable, with...
The capacitor will shift a bit the resonant frequency but will affect the efficiency of the monopole antenna.
Definitely the antenna efficiency will be better without capacitor.
Meanwhile, I think the circuit have too many matching components. Probably, two, maximum three, should be enough.
If the PA output impedance is 100 ohms and the load impedance is 20 ohms, you may need a matching network to do the matching between these two impedances.
Then, if the antenna has 20 ohms impedance, you will get the maximum power transfer between the PA and the antenna.
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