Available solutions include ellipsoidal reflector antennas and pyramidal/conical horns with a dielectric lens
in front of the antenna aperture, but they are quite bulky and heavy antennas at the microwave band.
The proposed structure is composed by 2 x 2 array of slot-ring antennas covered by a hemispherical dielectric lens
Metamaterials used for the dielectric lens
reduce its weight by about 90
In Section 2, the effective parameters of the proposed material are retrieved, the reasons for gain improvement by the proposed material are investigated, and for an end-fire antenna, the enhanced gain by a dielectric lens
and the ML-based material are compared.
To compensate this issue, a wideband dielectric lens
is placed in the aperture of each element.
Le Coq, "Flat-shaped dielectric lens
antenna for 60-GHz applications," IEEE Trans.
It can be obtained using a planar patch array [1,2], a slotted rectangular waveguide , a horn with metal plate lens [4,5] or with a dielectric lens
. In the latest case, the dielectric lens
can be placed in front of the horn  or inserted in the horn aperture [7, 8].
where N is normal to the hyperbolic surface, [p.sup.i] is the wave vector of the incident wave and n is the refractive index of the lens material which is normally a constant and is greater than unity for natural dielectric lens
. The wave vector of the incident waves, for both LCP and RCP, is given as:
The research used an in vitro exposure system developed by NTT DoCoMo that incorporated a horn antenna and dielectric lens
in an anechoic chamber.
It consisted of a feed antenna and a dielectric lens
that focuses microwave energy onto the sample.
The third method is parasitic ellipse and dielectric lens
. These two can increase the gain at a high frequency [28, 29].