Boonton 4240 RF Power Meter Bedienungsanleitung PDF herunterladen (Seite 112)

Boonton 4240 Series RF Power Meter

Frequenc

capaci

cannot

table f

Misma nding on the

mismat

minim

Signal

calibrat nal and second harmonic

combin

insigni egion (Region C, Figure 6-3), the detector responds to the vector sum of the signal and

harmo mplitude a between the harmonics and the fundamental,

measu ntly degrad even-order harmonics can be reduced by using

balanc er sensor. Thi o the peak-to-peak amplitude of the signal, which

remains constant f e relationship between ven-order harmonics. Unfortunately, for odd-order

harmo cs, the peak-to-peak signal amplitude is sensitive to phasing, and balanced detectors provide no harmonic error

improvement.

Noise. out. Balanced

detecto sensors i prove t ignal-to-noise ratio by 3 dB, because the signal is twice as large.

6.1.3

The 42

interna

•

• Digital Signal Processor provides fast processing for near real-time measurements.

h creates a unique calibration table for each sensor.

y Response. The carrier frequency response of a diode detector is determined mostly by the diode junction

tance and the device lead inductances. Accordingly, the frequency response will vary from detector to detector and

be compensated readily. Power measurements must be corrected by constructing a frequency response calibration

or each detector.

tch. Sensor impedance matching errors can contribute significantly to measurement uncertainty, depe

ch between the device under test (DUT) and the sensor input. This error cannot be easily calibrated out, but can be

ized by employing an optimum matching circuit at the sensor input.

Harmonics. Measurement errors resulting from harmonics of the carrier frequency are level-dependent and cannot be

ed out. In the square-law region of the detector response (Region A, Figure 6-3), the sig

e on a root mean square basis. The effects of harmonics on measurement accuracy in this region are relatively

ficant. However, in the linear r

nics. Depending on the relative a nd phase relationships

fica e ors caused by rement accuracy may be signi d. Err

diode d he powed etectors for t s design responds t

or any phas fundamental and e

For low-level signals, detector noise contributes to measurement uncertainty and cannot be calibrated

r m he s

4240 Series Features

40 Series design incorporates several significant features to reduce measurement error, simplify operation, and speed

l processing. These features include:

Balanced diode sensors enhance error performance by increasing signal-to-noise and suppressing even-

order signal harmonics.

• Smart Sensors (sensor-mounted EEPROM) store sensor frequency calibration eliminating operator entry.

• A built-in programmable calibrator whic

Application Notes

6-4

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