Multilayer Dielectric End-Fire Antenna With Enhanced Gain

The effect of a low permittivity cladding used in a multilayer end-fire dielectric rod antenna (DRA) design is studied in terms of return loss, gain, and half-power beamwidth (HPBW) in the extended Ku band (10-18 GHz). Gain improvement ranging from 4 to 7 dB, when compared to a single-layer design of the same length, is achieved using cladding permittivities between 1.6 and 2.6. For example, a cladding of ε
_r
= 1.6 leads to a peak gain increment of 4.5 dB at 18 GHz and a 20° HPBW reduction compared to the noncladded rod. It is also demonstrated that this design has the same maximum gain as a noncladded design that is 1.8 times longer. The cladding permittivity in the multilayer DRA can be adjusted to achieve peak performance at different frequencies within the band, while providing gain enhancement in the entire band without reducing the bandwidth.