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88-108MHz fm transmitter

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andy40185

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Hi all,

When I simulate the following circuit with pspice, there is no frequency output in the antenna.
Is anything exist for replacing the antenna?
Would anyone know the solution?
MCS_Lab6_Transmitter.jpg
 

SPIZERO

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Your antenna's length must be equal to carrier's wavelength.
Example:
lambda = c/f;
 

andy40185

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I think that there may not need to care the antenna length in simulation mode.
My problem is no frequency waveform output when simulating.
Should there be insert some source (like VSIN) in the base of Q2 or other place?
 

enjunear

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A quarterwave "whip" monopole will have an input impedance of Zin = 36.5 + j21.25 ohms at it's resonant frequency. A half-wave dipole would be 70 ohms. You can replace your antenna with one of these two loads, depending on what type of antenna you intend to drive. It should work as a first-order approximation.
 
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dick_freebird

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Still a transmitter needs a carrier waveform, if it's an AC analysis
you would need to figure out where to inject your reference tone
and if it's transient, give enough time & kick for the tank to ring up.
 

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