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Whip Antenna Design Calculator

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A whip antenna also known as a monopole antenna looks capacitive if it is shorter than a quarter wavelength, and are tuned to resonance with a series inductor.  PCB antennas are often shorter than a quarter wavelength due to board size restrictions and often fit into this category.  

The capacitance is related by a formula and is a function of the percentage of wavelength.  The matching inductor is chosen such that the antenna resonates at the desired frequency.  When the antenna is perfectly tuned then it looks like a pure resistance tied to ground.  This resistance is known as the radiation resistance.  

F (frequency) (MHz)
L (length) (inches)
D (diameter) (inches)

C (capacitance of antenna) (pF)
L (tuning inductance) (nH)
Lambda/4 (1 quarter wave length) (m)
Antenna length as percentage
of a quarter wave length.
Rr (Aprox Radiation Resistance)
Calculated if < 1/8 wave length


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