Radiation from a two-arm metamaterial spiral

The MTM spiral has an extremely low-profile structure, radiating an LH CP wave at frequencies near f
_N
and an RH CP wave at frequencies near f
_H
, i.e., it has a dual-band anti-CP radiation characteristic. The gain bandwidth for the LH CP is 14.5% around frequency fLH-G and the gain bandwidth for the RH CP is 14.0% near frequency fRH-G. As the number of arm filaments is increased, the gain increases. The radiation pattern at fRH-G has a narrower beam width compared with that at f
_LH-G
.