If an antenna is much longer than the wavelength, what is the typical result?

The antenna will not work very well. In fact, an antenna is able to amplify the input signal (the radiowave) when its resonant frequency matches the frequency of the input wave. This condition occurs when the length of the antenna is comparable to the wavelength of the input wave, and then resonance occurs, and the signal is amplified. On the contrary, if the length of the antenna is much larger, then no resonance occurs, and the antenna is not able to amplify the signal.