A | B | C | D | E | F | G | H | I | L | M | N | P | R | S | T | V | Y | Z

F

FREQUENCY ACCURACY
Drift
Modern analyzers are tuned by a synthesized LO. All frequencies are derived from one crystal oscillator the so-called reference oscillator with frequency accuracy in the lower ppm range and even lower.

FREQUENCY BAND
Depending on the technical concept the frequency measurement range of the analyzer can be subdivided into "frequency bands". This applies in particular to units having a high upper frequency limit (> 26.5 GHz). This concept can mostly be found with older units. Modern analyzers practically use bands only with harmonic mixers. Example: With a harmonic mixer the frequency bands are produced by mixing each input signal with one harmonic of the local oscillator.
Only down conversion is used; IF conversion is according to the following relationship:

f_IF = |n x f_LO - f_RF|
(n > 1, f_IF < f_RF, f_IF < f_LO)

FREQUENCY DOMAIN REFLECTOMETRY (FDR)
FDR is the measurement of signal reflections through a device under test (DUT) across a certain frequency range. A portion of the test signal transmitted into the DUT will be reflected back to the transmitter if either the impedance inside the DUT or the load on the end of the DUT does not match the correct impedance (typically 50 ohms).

FREQUENCY RESPONSE
Describes the frequency-dependant level error over a given frequency range. Any variation is undesirable.

FREQUENCY RESPONSE CORRECTION
Automatic correction of the error in the measured level due to the frequency response of the analyzer. Frequency response correction often occurs only at the set center frequency (CENT). High-performing analyzers offer frequency response correction which covers the whole frequency range displayed.

FREQUENCY SPAN
Span

FULL SPAN
A sweep across the entire frequency range of the analyzer including automatic switching between the frequency bands.

FUNDAMENTAL MIXER
A mixer stage which only makes use of the local oscillator fundamental frequency f_LO for heterodyning. IF conversion is according to the following relationship:

f_IF = |f_LO - f_RF|

If f_IF, f_LO are > f_RF => up conversion
If f_IF, f_LO are < f_RF => down conversion

^ top