Fig. 1. Area calculation of polygons in the physical space with the separation angle of θi. (a) Polygon (triangle) is completely located at the gray area; (b) polygon spans the beige and gray areas; (c) polygon is completely located at the beige region

Fig. 2. Distribution of electric field and dielectric constant of the four-beam lens antenna. (a) Near electric field distribution and (b) dielectric constant distribution when R=2λ; (c) near electric field distribution and (d) dielectric constant distribution when R=4λ

Fig. 3. Permittivity distribution and equivalent parameter inversion results of the four-beam antenna. (a) Continuous distribution of the permittivity values; (b) discrete distribution of the permittivity values; (c) equivalent parameters inversion result of the cell grid under different drilling-hole diameters

Fig. 4. Geometric structure of the four-beam lens antenna. (a) Top view; (b) side view; (c) side view of equivalent medium lens

Fig. 5. Parametric characteristic distributions of the dipole antenna and the proposed four-beam lens antenna. (a) S11; (b) VSWR

Fig. 6. Comparison of radiation gain between the dipole antenna and the proposed our-beam lens antenna at different frequencies. (a) E plane and (d) H plane gains at 5.8 GHz; (b) E plane and (e) H plane gains at 6.0 GHz; (c) E plane and (f) H plane gains at 6.2 G

Fig. 7. Influence of frequency on the gain and directivity of the dipole antenna and the proposed four-beam lens antenna. (a) Relationship between frequency variation and the maximum gain; (b) relationship between frequency variation and directional amplitude