Use of spectrum analyzer for antenna measurement

Dear all,
Is it possible to measure and test any parameter of a patch antenna using a spectrum analyser?

Thanks in advance :)

Not on its own it is just an indicator of signal level. Assuming you wnat to measure VSWR you will need a signal source and directional coupler. For polar diagram a signal source, test antenna, test range & turntable.

Thank you so much for the reply:)
Can we measure reflection coefficient?

Some spectrum analyzers have a built-in sweep generator enabling it to perform gain measurements, or with the help of a directional coupler, also reflection measurements. G4BCH mentioned the latter.

You can also use a separate manually tuned, non-synchronized RF generator if you run the SA in repeated sweep with peak hold.

Measuring antenna gain with either two identical antennas for RX and TX or the antenna under test and a reference antenna is a possible application. You'll of course pick up RF from the environment and risk to disturb other radio services.

As stated, you need a signal source, and two KNOWN gain antenna standards. You set up your test with the gain standard antennas, sweep the frequency, record the results, and that is your "calibration". You then replace one of the gain standards with your device under test, and can figure out the gain vs. frequency and angle.

Many spectrum analyzers have poor VSWR on the input, so resist the temptation of removing all of the passive attenuator padding in the front end when making the measurement.

Following the substitution method, using a signal generator and a dipole antenna (built for the test frequency) you can find the gain of your patch antenna in dBd.
dBd means the antenna gain with respect to a reference dipole antenna.
http://www.m2inc.com/blog/dbi-vs-dbd/