Complex sentence: When using a rectifier for demodulation the capacitor and load resistance must be carefully matched: too low a capacitance will result in the high frequency carrier passing to the output, and too high will result in the capacitor just charging and staying charged.
Split into simpler sentences: When using a rectifier for demodulation the capacitor and load resistance must be carefully matched. Too low a capacitance will result in the high frequency carrier passing to the output and too high will result in the capacitor just charging and staying charged.