Depending on the duration of the beacon signal, you might actually have trouble with the SSA3021-Plus.
Note that this spectrum analyzer does not look at the selected frequency range in realtime, but instead will sweep from start frequency to end frequency. Depending on the RBW/VBW and frequency range, one sweep might take longer than the short bleep of your beacon signal! There is only one way to find out: fnd out how long the signal is on and how long it takes to sweep the frequency range of interest.
A good example if WIFI: you will get poor results measuing it with a regular spectrum analyzer, due to the channel hopping.
What you need is a realtime spectrum analyzer, than can capture a whole frequency range in one go. Of course they are a magnitude more expensive than swept spectrum analyzer.
A cheap alternative - cheap enough for testing purposes and get you started, would be a SDR based spectrum analyzer, like RTL2832U dongles, HackRF, Adalm Pluto, etc. Note that those can be used to visualize the presence of the signal and demodulating the signal (when applicable and with available software based demodulators), but you won't be able to make quantitative measurements.
regards,
Vitor