A Compact Tri-Band Structure-Shared End-Fire Antenna with High Isolation

In this paper, a compact tri-band structure-shared end-fire antenna is designed with high isolation. The tri-band antenna is composed of a dielectric double-sided printed dipole antenna (DSPDA) connected with substrate integrated waveguide (SIW) and two dielectric rod antennas (DRA) fed by the waveguide, which work at X-band and K-&Ka-bands, respectively. The opposite broad walls of two waveguides are replaced by SIW. Due to the DSPDA working at x-band, the corresponding SIW is wider than the broad wall of waveguide, so these antennas can be tightly nested together, resulting in a compact structure. Furthermore, through the design of the matching section, two dielectric rods effectively excited by the feeding waveguides transmit surface waves, thus there is a natural high isolation characteristic between two DRAs. The polarization orthogonality of the electric field between the DSPDA and two DRAs enables high isolation performance of tri-band antenna. The DSPDA and DRAs utilize the taper structure at the top to realize the wave impedance matching, to obtain good matching and minimize the back radiation.