[Amps] resonance

[Bill Fuqua]

>Date: Mon, 05 Jun 2006 10:31:08 -0400
>To: "Jim Forsyth" <jim at forsyth.net>
>From: Bill Fuqua <wlfuqu00 at uky.edu>
>Subject: Re: [Amps] resonance
>
>Yes there are subtile differences but they all go to the nature of a 
>balance between maximizing the stored energy. Balance does not always mean 
>equal but in most cases equal is accepted as a definition but not precise. 
>The definition ( opening statement) is precise no matter if you are 
>talking about pendulums, atoms, molecules, crystals, piano strings, etc. 
>And a pure resistance is not resonant. I have heard people refer to B&W's 
>folded dipole as being resonant on all frequencies. That is definitely not 
>true.  It may be a good match and even radiate on all frequencies but not 
>resonant on them.
>
>
>
>73
>Bill wa4lav
>
>
>At 07:08 AM 6/5/2006 -0700, you wrote:
>>Needs more refinement! In a parallel tuned circuit containing resistance, Xl
>>and Xc are not equal at the resonant frequency.
>>
>>
>>----- Original Message -----
>>From: "Bill Fuqua" <wlfuqu00 at uky.edu>
>>To: "Amps" <amps at contesting.com>
>>Sent: Monday, June 05, 2006 6:51 AM
>>Subject: [Amps] resonance
>>
>>
>> > Maybe it is time to change the thread.
>> >   Passive Resonance is a frequency selective means of storing oscillating
>> > energy. It occurs when energy oscillates back and forth between two
>> > complementary energy storage mechanisms. In the case of the pendulum you
>> > have kinetic and potential energy.   In a circuit the storage mechanisms
>> > are the inductance and capacitance. The inductance is the kinetic energy
>> > storage mechanism  and  the capacitance is the potential storage
>> > mechanism.  When there is a balance between these  Xc=Xl the circuit is at
>> > resonance. That is because all the energy from one goes to the other and
>> > back except for the bit that is lost in the resistance. A pure resistance
>> > alone is not resonant. That is the flaw in defining resonance as when
>> > Xc=Xl
>> > alone.  In a resistor zero does equal zero at all frequencies.
>> >    Another property of resonance is that besides selectivity the energy
>> > stored in the system is greater than that passing to or from it when at
>> > equilibrium. And the Q is the amount of energy stored divided by the
>> > amount
>> > of energy going into the resonant system during each cycle. We usually see
>> > the other definitions regarding  reactance and resistance and bandwidth
>> > and
>> > resonant frequency. All three produce the same unit-less value.
>> >    I use the term passive because some of the properties of passive
>> > resonance (not all) can be accomplished by active filters and by digital
>> > methods.  Even though a "flywheel" may store oscillating energy it is not
>> > frequency selective, thus not resonant. We often use the term "Flywheel
>> > Effect" but "Pendulum Effect" may be more accurate.
>> >
>> > 73
>> > Bill wa4lav
>> >
>> >
>> > At 10:45 PM 6/4/2006 -0400, Bill Coleman wrote:
>> >
>> >>On Jun 4, 2006, at 8:23 AM, R L Measures wrote:
>> >>
>> >> > My dummy load is non-resonant, so that's a problem?
>> >>
>> >>Dummy loads are resonant by definition, since they provide a purely
>> >>resistive impedance. (ie X = 0 is the definition of resonance)
>> >>
>> >>
>> >>
>> >>Bill Coleman, AA4LR, PP-ASEL        Mail: aa4lr at arrl.net
>> >>Quote: "Not within a thousand years will man ever fly!"
>> >>              -- Wilbur Wright, 1901
>> >>
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>>
>>
>>
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