critical frequency


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critical frequency

[′krid·ə·kəl ′frē·kwən·sē]
(electronics)
(electromagnetism)
The limiting frequency below which a radio wave will be reflected by an ionospheric layer at vertical incidence at a given time.
(geophysics)
The minimum frequency of a vertically directed radio wave which will penetrate a particular layer in the ionosphere; for example, all vertical radio waves with frequencies greater than the E-layer critical frequency will pass through the E layer. Also known as penetration frequency.
References in periodicals archive ?
4 was applied to the PP and PO data to determine a critical frequency as a function of stress amplitude.
In this particular study, the sampling distribution of critical frequency and electron concentration are presented in histogram plots shown in Fig.
In another study, Zagatto and colleagues (27) with the objective of testing the validity of the critical frequency model determined by using a specific protocol on table tennis, the researchers analyzed the aerobic (critf) and anaerobic (anaerobic work capacity--AWC) parameters of the model, the realization of two specific tests on table tennis and two on conventional ergometers were proposed.
These procedures were lactate minimum, critical frequency and anaerobic threshold tests.
3 shows that a small change in magnetrons frequency [11] causes significant change in guided wave length because of operating near critical frequency.
Replacing the values from table 1 in the relation (3) the critical frequency can be obtained 82 Hz.
The maximum frequency at which reflection can occur is also a function of the elevation angle (0 in Figure 1) and the critical frequency ([F.
Chilling atoms improves atomic-clock performance because cold atoms move more slowly, making it possible to detect more precisely their response to microwaves of a critical frequency.
Just a day before the Board unanimously voted to strengthen and adopt the resolution calling on the President and Congress to halt further proposed auctions of spectrum, President Clinton proposed yet another auction - this one in a critical frequency area to state and municipal Public safety.
By utilizing SSCG, EMI can be reduced by up to 15 dB in the critical frequency bands deterministically, thereby reducing engineering iterations to ensure EMI compliancy considerably.
It utilizes a fixed 2MHz switching frequency, enabling designers to minimize external component sizes and avoid critical frequency bands, such as AM radio.

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