Contents
What does reactance represent?
In electric and electronic systems, reactance is the opposition of a circuit element to the flow of current due to that element’s inductance or capacitance. As frequency increases, inductive reactance also increases and capacitive reactance decreases.
What is reactance in a circuit?
Reactance, in electricity, measure of the opposition that a circuit or a part of a circuit presents to electric current insofar as the current is varying or alternating. Steady electric currents flowing along conductors in one direction undergo opposition called electrical resistance, but no reactance.
What is antenna resonance?
A resonant antenna, or resonant-length antenna, is an antenna whose length is a quarter of a wavelength, or multiples thereof, long. In this case, the antenna is purely resistive and its reactance is zero, and hence the maximum amount of current flows through the antenna.
What is reactance example?
Reactance sometimes occurs when a person makes a choice that cuts off other choices. For example, Charlie gets a certain amount of lunch money every day at school and can choose what he wants, but he can’t have it all.
Why is reactance used?
Reactance (also known as electrical reactance) is defined as the opposition to the flow of current from a circuit element due to its inductance and capacitance. The reactance is used to compute this change in phase and magnitude of the current and voltage waveforms.
How is the reactance of an antenna reduced?
Antenna potential is reduced by minimizing antenna reactance at the working frequency. This in turn is accomplished by minimizing the characteristic impedance of the antenna system and by top loading it with as much capacitance as can be afforded.
What is the resonance point of a mobile antenna?
At resonance, the input impedance of a decent-quality, correctly-mounted, HF mobile antenna will be about 25 ohms. By definition, the resonance point is where the reactive component equals zero (X=Ø, or +Øj if you prefer). Since the requisite impedance of our feed line is 50 ohms, the resulting SWR would be 2:1.
How does inductive matching work on an antenna?
Inductive matching works by borrowing a small amount of capacitive reactance from the antenna (by tuning the antenna slightly above the actual transmitting frequency).
What is the reactance of a transmission line?
Applying the transmission-line analosgy, the reactance of an open-circuited line of characteristic impedance Z0and electrical length G is With capacitive top loading of a vertical radiator of electrical height Gν and characteristic impedance Z0with a fiat-top of reactance X1at a frequency f1, the reactance at the feed point would be