A video discussing RSSI, RSRP, RSRQ and SINR, indicators that you can use to check whether the antenna improves your signal.
RSSI – Received Signal Strength Indicator
RSRP – Reference Signal Received Power
RSRQ – Reference Signal Received Quality
SINR – signal-to-interference-plus-noise ratio
SNIR – Signal-to-noise-plus-interference ratio
SNR – Signal to Noise Ratio.