The vertical folded loop antenna, modeled as wire and printed radiatin
g element mounted on a conducting box, simulating a cellular telephone
with and without dielectric coating, is analyzed. Finite-difference t
ime-domain (FDTD) method is used to calculate radiation patterns and i
nput impedance. The results are compared with measurements and with NE
C data, Very good agreement is obtained in all cases, Parasitic loadin
g is used to enhance the bandwidth of the printed element, The antenna
meets design requirements for existing and future mobile communicatio
n systems.