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J

Jean

Jan 1, 1970
0
I am beginner in Radio..
After learning the basics I have several doubts..
Please clear them
Where shall I begin to start experimenting with radio ?
Will an oscillator radiate if its output is connected to an antenna ?
How to measure reactance of an antenna?
How can you easily detect radiation of a particular frequency ?
How to radiate more power through a given antenna ?
How to calculate power radiated by an antenna ?
.......

Help me through google
 
J

John Popelish

Jan 1, 1970
0
Jean said:
I am beginner in Radio..
After learning the basics I have several doubts..
Please clear them

(I am replacing your > marks with numbers, since those characters are
normally used to indicate quoted text, on usenet.)
1. Where shall I begin to start experimenting with radio ?

Build a crystal set. It is essentially an antenna, a resonator (to
select the station) and a rectifier to demodulate AM. Many variations
can be built on to that simple starting circuit.
2. Will an oscillator radiate if its output is connected to an antenna ?
Yes.

3. How to measure reactance of an antenna?

Measure it as you would any reactance with a bridge. The difficulty
is that the bridge must be excited with the operational frequency.
Any reactance that is based on standing waves is very frequency
dependent.
4. How can you easily detect radiation of a particular frequency ?

Easily is in the eye of the beholder. First you have to select one
frequency range from all the frequencies that are mixed in the space
around the antenna. The simplest involves a resonant circuit. Then
you need a method of measuring the energy in the resonator. A diode
detector is just a rectifier that converts AC to DC, so that you can
make a DC measurement and interpret that as an AC measurement. But
you could also convert the AC to heat and use the temperature rise as
a measurement of magnitude.
5. How to radiate more power through a given antenna ?

Apply more voltage to it.
6. How to calculate power radiated by an antenna ?

This is a tough one. The math must model not only the antenna, but
its surroundings (reflections, ground resistance, etc.). It is often
easier to make a field strength meter and measure (at least
comparatively) the radiation produced by various transmitter and
antenna combinations at a distance of a few wavelengths (to minimize
near field coupling effects).
Help me through google

What sort of problems are you having with google?
 
N

N. Thornton

Jan 1, 1970
0
John Popelish said:
Build a crystal set. It is essentially an antenna, a resonator (to
select the station) and a rectifier to demodulate AM. Many variations
can be built on to that simple starting circuit.

Hi

This is always a question that brings up varying opinions. I'm one of
the folk that recommends not making crystal sets, since
a) they fail to work more often than not,
b) the results are dismal
c) with a few more components you can make something you can enjoy
listening to.

A 2 stage reaction receiver (aka regenerative) gives great results for
a small simple circuit, but they are pretty fussy to work with, as
they are inherently unstable. A darlington rf transistor amp, diode
detector, plus one audio output transistor is enough to give genuinely
good quality with loudspeaker volume and a reception of 2 or 3
stations: for a 2 stage radio thats remarkable. Plus it gives endless
twiddling opportunity.


Regards, NT
 
W

Walter Harley

Jan 1, 1970
0
Jean said:
I am beginner in Radio..
After learning the basics I have several doubts..

Beg, borrow, or steal a copy of the "ARRL Handbook". Used is just as good
as new; they have an edition every year or so and I use my 1974 just as
often as my 1996. But newer ones will focus more on newer technology, which
is probably a good thing for you.

It is full of useful theory and practical projects, aimed at people just
like you.

Google is not a good tool for learning bodies of knowledge. It is sometimes
good if you have a specific question.
 
L

Luhan Monat

Jan 1, 1970
0
Walter said:
Beg, borrow, or steal a copy of the "ARRL Handbook". Used is just as good
as new; they have an edition every year or so and I use my 1974 just as
often as my 1996. But newer ones will focus more on newer technology, which
is probably a good thing for you.

It is full of useful theory and practical projects, aimed at people just
like you.

Google is not a good tool for learning bodies of knowledge. It is sometimes
good if you have a specific question.
I learned form the 1953 edition when I was 10. I agree, its still the
best thing I have ever found for beginners.
 
P

Paul Burridge

Jan 1, 1970
0
I learned form the 1953 edition when I was 10. I agree, its still the
best thing I have ever found for beginners.

I would add that, like our own UK equivalent, "Radio Communication",
the older editions are probably more valuable to the beginner than the
later ones. IC-based design tells you nothing. You need to see how
discretes can be assembled into useful circuits to expand on the
basics and the *earlier* editions of both books do this brilliantly. I
personally still like reading up about valves (sorry - "toobz")
 
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