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Form the product C 2 ( R 1 + R 2). Select capacitor C 1, replace it by a test voltage V X, and replace C 2 by an open circuit. Then the resistance seen by the test voltage is found using the circuit in the right panel of Figure 1 and is simply V X / I X = R 1. Form the product C 1 R 1. Add these terms.
The cutoff frequency when expressed as an angular frequency (=) is simply the reciprocal of the time constant. Short conditional equations using the value for / (): f c in Hz = 159155 / τ in μs τ in μs = 159155 / f c in Hz. Other useful equations are:
The cutoff frequency is found with the characteristic equation of the Helmholtz equation for electromagnetic waves, which is derived from the electromagnetic wave equation by setting the longitudinal wave number equal to zero and solving for the frequency. Thus, any exciting frequency lower than the cutoff frequency will attenuate, rather than ...
where is the wavelength expressed in millimeters and F # is the lens' focal ratio. As an example, a telescope having an f /6 objective and imaging at 0.55 micrometers has a spatial cutoff frequency of 303 cycles/millimeter. High-resolution black-and-white film is capable of resolving details on the film as small as 3 micrometers or smaller ...
Alpha cutoff frequency, or is the frequency at which the common base DC current gain drops to 0.707 of its low frequency value. The common base DC current gain is the ratio of a transistor's collector current to the transistor's emitter current , or α = i C i E {\displaystyle \alpha ={\frac {i_{C}}{i_{E}}}} .
The half-power point is the point at which the output power has dropped to half of its peak value; that is, at a level of approximately −3 dB. [1] [a]In filters, optical filters, and electronic amplifiers, [2] the half-power point is also known as half-power bandwidth and is a commonly used definition for the cutoff frequency.
In digital signal processing (DSP), a normalized frequency is a ratio of a variable frequency and a constant frequency associated with a system (such as a sampling rate, ). Some software applications require normalized inputs and produce normalized outputs, which can be re-scaled to physical units when necessary.
In radio-frequency engineering and communications engineering, a waveguide is a hollow metal pipe used to carry radio waves. [1] This type of waveguide is used as a transmission line mostly at microwave frequencies, for such purposes as connecting microwave transmitters and receivers to their antennas, in equipment such as microwave ovens, radar sets, satellite communications, and microwave ...