i need please to know what is the purpose of using the inductor in a radio communication system ?
Hi, the inductor in the simplest RF circuit is used with a capacitor to form what is called a resonant circuit, they are used to make oscillators, rf amplifiers, and filters.
If you google resonant LC circuit , there are many sites that will explain it.
i am reading about it in a book, but i didn't really get the idea,
what till now it talks about inductance, magnetic fields and else but how will this lead to form an oscillator ?!
and is this the main idea behind the RF signal when using an antenna ?!
Because you need LC tuned circuits. For instance most RF amplifier stages are coupled
together with tuned transformers (except when they are all integrated on one piece of
silicon). Tuned transformers both allow impedance matching and filter out-of-band signals
and noise at each stage, and minimize energy loss (resistors dissipate signal as heat, not
what you want when amplifying up to high powers)
For more information sites and publications aimed at radio amateurs go into a lot more
Because the inductor complements the capacitor. When excited by an AC signal the reactance of the capacitor is imaginary-negative and the reactance of the inductor is imaginary-positive. Given any inductor and capacitor, at a certain frequency the inductive and capacitive reactances cancel out which will affect only one frequency, leading to a frequency selective circuit.
Why do you think they use capacitors in RF circuits?
Its worth noting that some RF circuitry doesn't make use of inductors, this being
"broadband" circuitry where loads are resistive and impedances are kept low to
reduce the problem of stray capacitance. However such broadband circuitry is
prone to spurious signals creeping in at unwanted frequencies, and often filter
devices such as SAW filters, quartz crystals and such like are employed at strategic
points to remove spurious signals if possible.
The best sensitivity and selectivity in radio receivers can only be achieved via tuned
preamps and superhet frequency conversion to a fixed-frequency IF strip (lots of
terms to google there).
Interestingly a quartz crystal resonates like a super high-performance LC tuned
circuit (very large inductance, very small capacitance, in fact).
ok thanks guys,
all i have to do now is keep reading and try the understand as much as i can from the book The arrl handbook