SMA to SMA connector

Please can anyone help me as to what options I can use for connecting one sma connector to another sma connector ? I have to connect a rectifier circuit to the patch antenna for RF energy harvesting.
Also how do I measure the output (using which instrument)?

Please help me thanks in advance :)

"SMA connector" can be plug or jack. To connect two jacks, use a SMA cable or a plug-to-plug adapter https://www.amphenolrf.com/132168.html

You can use a Spectrum Analyzer to measure your antenna's properties.

While I can advise you to use a cable assembly of sma-sma coaxial cable since you probably need to move the antenna around without distortion.

Can you please tell me if I need a transmitter antenna as well at the particular frequency to measure an antenna's spectrum in the spectrum analyser.

i think you are referring to antenna radiation pattern. in order to measure antenna radiation pattern, you need anechoic chamber and spectrum analyzer. the setup is very complex so usually ppl will rent test labs to measure antenna radiation pattern.

Actually, I have been told to observe the frequencies of resonance of an antenna in the frequency domain. When I connected the antenna, there is no spectrum visible at the frequencies of resonance of the antenna. Is it necessary that it receives the particular frequencies from the surroundings, or is it just like the VNA measurement.

you are trying to do return loss (S11) measurement on a VNA. VNA have signal internally and it will inject the signal and measure the S11.

make sure that you calibrate your VNA.