Measured Performance of Dielectric Rod EBG Leaky-Wave Antenna

In this contribution we present the design and experimental validation of a novel Electromagnetic Band-gap (EBG) leaky-wave antenna (LWA) that operates in the K-band. A study of the radiation mechanisms of 2-D dielectric lattices has been presented in [1]. An approach based both on the analysis of the band diagrams of the Bloch waves propagating in the 2-D EBG and the properties of bound and leaky modes in transversely open lattice waveguides is shown in [2], which provides an interesting perspective for antenna design. Here, we propose a 3-D realistic configuration of EBG LWA. The structure consists of $7 \times 8$ alumina cylinders with nominal dielectric permittivity of $\varepsilon_{r}=9.8$. The cylindrical rods, of radius 1.245 mm, are placed above a ground plane and supported by two vertical metal plates. The period of the structure is equal to 4.1 mm. The size of the structure, dimensioned to operate around $f=24 \mathrm{GHz}$, are $21.5 \times 39.8 \times 28.7 \mathrm{~mm}$. The distance between the two metal wall is 13.5 mm. The antenna, shown in Fig. 1(a), is fed by two counterphase monopoles. A rat-race hybrid junction, located below the antenna, feeds the two monopoles. The proposed structure was first simulated in CST Microwave Studio showing a very good agreement between CST total field and the dominant leaky mode. Fig 1(b)-(c) show the comparison between simulated and measured radiation patterns in the E-plane and H-plane, respectively. The measured directivity is 12.7 dBi at $f=24.6 \mathrm{GHz}$. The measured reflection coefficient at $f=24.6 \mathrm{GHz}$ is $\left|S_{11}\right|=-24 \mathrm{~dB}$. More details will be presented at the conference.