HFSS Electrically Small Antenna Simulation

When we simulate an antenna using HFSS, an air box with a distance of quarter wavelength from the radiator usually should be created.

I am trying to simulate an antenna with frequency range of interest from 50 MHz to 500 MHz. Should I still use a quarter wavelength air box in the simulations. A quarter wavelength will be 1.2 m, which is too large, and will cause the simulation very slow.