the end walls is nλp, where n is any integer. Actually, placement of the first wall ensures standing waves
and placement of the second wall permits oscillations, provided that the second wall is placed so that
the pattern due to the first wall is left undisturbed. Thus, if the second wall is λp/2 away from the first,
oscillation between the two walls will take place. This will then continue until all the applied energy is
dissipated, or indefinitely if energy is constantly supplied.
Any space enclosed by conducting walls must have atleast one (or more) frequency at which the
oscillation called the resonant frequency. Indeed, the completely enclosed waveguide at this condition
becomes a cavity resonator with its own system of modes, and therefore resonant frequencies. Each
cavity resonator has an infinite number of resonant frequencies.
Types of cavity resonator include spheres, cylinder or rectangular prisms. However such cavities are not
often used, because they all share a common defect that their resonant frequencies are harmonically
related. As a result, most practical cavities have odd shapes to ensure that the various oscillating
frequencies are not harmonically related. Typical irregularly shaped resonators are the reflex klystrons
and magnetrons.
Cavity resonators are input or output to tuned circuits of amplifiers, tuned circuits of oscillators, or
resonant circuits used for filtering e.t.c. They can also be given shapes that make them integral parts of
microwave amplifying and oscillating devices. One major application of the cavity resonator is as a cavity
wave meter, used as a microwave frequency-measuring device.
1.1.MICROWAVE SOURCES
1.1.1. ACTIVE MICROWAVE DEVICES
(a) KLYSTRON
A type of vacuum tube used as an amplifier and/or oscillator for UHF and microwave signals. It is
typically used as a high-power frequency source in such applications as particle accelerators, UHF TV
transmission and satellite earth stations. The klystron was invented at Stanford University in 1937 and
originally used as the oscillator in radar receivers during World War II.
A klystron tube makes use of speed-controlled streams of electrons that pass through a resonating
and placement of the second wall permits oscillations, provided that the second wall is placed so that
the pattern due to the first wall is left undisturbed. Thus, if the second wall is λp/2 away from the first,
oscillation between the two walls will take place. This will then continue until all the applied energy is
dissipated, or indefinitely if energy is constantly supplied.
Any space enclosed by conducting walls must have atleast one (or more) frequency at which the
oscillation called the resonant frequency. Indeed, the completely enclosed waveguide at this condition
becomes a cavity resonator with its own system of modes, and therefore resonant frequencies. Each
cavity resonator has an infinite number of resonant frequencies.
Types of cavity resonator include spheres, cylinder or rectangular prisms. However such cavities are not
often used, because they all share a common defect that their resonant frequencies are harmonically
related. As a result, most practical cavities have odd shapes to ensure that the various oscillating
frequencies are not harmonically related. Typical irregularly shaped resonators are the reflex klystrons
and magnetrons.
Cavity resonators are input or output to tuned circuits of amplifiers, tuned circuits of oscillators, or
resonant circuits used for filtering e.t.c. They can also be given shapes that make them integral parts of
microwave amplifying and oscillating devices. One major application of the cavity resonator is as a cavity
wave meter, used as a microwave frequency-measuring device.
1.1.MICROWAVE SOURCES
1.1.1. ACTIVE MICROWAVE DEVICES
(a) KLYSTRON
A type of vacuum tube used as an amplifier and/or oscillator for UHF and microwave signals. It is
typically used as a high-power frequency source in such applications as particle accelerators, UHF TV
transmission and satellite earth stations. The klystron was invented at Stanford University in 1937 and
originally used as the oscillator in radar receivers during World War II.
A klystron tube makes use of speed-controlled streams of electrons that pass through a resonating
