what's the difference of vector/scalar network analyzer?

Both types measure the two port parameters. The vector type gives you magnitude and phase. The scalar is just magnitude.

I have never heard of a nonlinear network analyzer.

A Scalar Analyzer is kind of like a sweepped Spectrum Analyzer
with a S11 read out(you can see gain or Power but don't trust the
power reading use a power meter), and the VNA gives all
S-Parameters. This just a basic explanation

Hope this helps

The scalar is just magnitude so u can not mesure phas and it is less aqurde ( .

Some Scalar analyzers use power sensors to measure the magnitude. The power sensor usually measures the total power of the whole spectrum (including fundamental signal and its higher order components)

There is a nice appnote on the @gilent test and measurement site (replace @ with a), it describes the principles of operation

http://we.home.@gilent.com/upload/cm...T_NABASICS.pdf

The NA-s could be scalar and vector types, but the detection modes also could be wide band (diode) and narrow band (tuned receiver).

I have at my work a scalar network analyser with wide band diode detector, and some times it gives me a lot of headache due to the wide band nature of the detector(especially when I am testing filters): it is very sensitive to the harmonic content of the sweep generator.

Regards, Al

Nonlinear network analyzer can give you also the amplitude and phase of the harmonic which is generated by the nonlinear circuit.

I was at Agilent workshop last year when they presented nonlinear/ large S par NA. Nonlinear NA is for the moment in development phase, it is not a piece of equipment but a number of instruments, including a standard NA, harmonic tuners etc. You can measure, as stated above, a complete nonlinear behaviour of your device. Results shown are quite promising for accurate prediction e.g. of PA performance concerning IMD and other nonlinear parameters. It is quite a procedure to use, a simple measurement is a whole day exersise including very complicated callibration. Even a mesured data interpretation is not straight forward, Agilent can do it for you as a service.

flyhigh

NVA can measure the all phase parameter