I am wondering how people manage signals in the high frequency range (77+GHz). How do people connect a differential Tx radar signal and sample it on a Spectrum Analyzer? Articles and books would be very helpful. I understand pcb patch antennas are more common in this frequency range but i need to find more information on it.
To answer your spectrum analyzer question:
Very high end spectrum analyzers, such as Keysight's N9041B UXA Signal Analyzer, can take frequencies up to 110 GHz. You can even do low-THz signals with the proper mixing.