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This letter presents a wideband three-dimensional (3-D)-printed circularly polarized (CP) ultrathin dielectric slab waveguide (DSW) Luneburg lens (LL) with multibeam application in X-band. The characteristic that DSW supports TE0 and TM0 waves to pass through with different phase constants is used to generate 90° phase difference to compose CP wave for the proposed structure. To prove the point, the prototype antenna is fabricated by 3-D printing and measured. The results show that the proposed LL supports multibeam application with 11 beams covering ±60° range in azimuth plane, and the 3 dB axial ratio bandwidth for multibeam antenna is 23.5% with reflection coefficient lower than −10 dB and gain higher than 13.7 dBi. The measured results show good coincidence with simulated ones. [ABSTRACT FROM AUTHOR]

This letter presents a simple method to design the wideband circularly polarized spherical multibeam Luneburg lens (LL) antenna by using three-dimensional (3-D)-printing. The conventional 3-D-printed spherical LL is divided into many cells and each cell is filled by the unit cell with different filling ratios, which breaks the circular symmetry of the LL. The proposed method divides the LL into many layers, and the profile surface equation of each layer is calculated by the ordinary least square method to keep the rotation symmetry of the LL. Then, according to the proposed circularly polarized implement method, the transformation of linear polarization to circular polarization can be realized by selecting a proper radius of LL. The simulated and measured results show that the axial ratios of the proposed multibeam LL antenna are less than 3 dB with good impedance performance and more than 13.8 dBi gain in a relative bandwidth of 31.6%, which demonstrates the validity and simplicity of the presented method. [ABSTRACT FROM AUTHOR]

In this article, a broadband dual circularly polarized (CP) antenna with simple structure and high gain is designed. A metal ridge septum with the shape of the cascade of a rectangle and a triangle is embedded into the square waveguide to excite CP wave, which is presented through analysis and simulation. By feeding the antenna at the two positions with respect to the symmetrical position of the septum, it can form the right‐handed circularly polarized (RHCP) and left‐handed circularly polarized (LHCP) wave, respectively. To verify the design, a prototype of the antenna is fabricated and measured. The measured and simulated results coincide with each other. According to the simulation and measurement, the designed antenna can work well within a relative bandwidth of 64% from 8.5 to 16.5 GHz. The proposed dual CP antenna has the simple configuration and good performance, and it can be a good candidate antenna for the broadband communication system. [ABSTRACT FROM AUTHOR]

This letter presents a broadband 3-D-printed circularly polarized (CP) spherical Luneburg lens (LL) with the linearly polarized feed antenna for the X-band. In order to implement spatially continuous varying effective refractive index (RI), the proposed LL is divided to many unit cells and their effective RI is simulated and calculated by effective medium theory. Since the effective RI of unit cells is anisotropic for two orthogonal linearly polarized (LP) waves, the proposed LL is an LP to CP polarizer realized by properly selecting the radius of the LL. The whole structure is fabricated by low cost 3-D-printing (3DP) technic, which is fed by an LP antenna source rotated to a certain angle with respect to the LL around the normal. The measured results indicate that the voltage standing wave ratio (VSWR), axial ratio, and gain enhancement are lower than 2, less than 2.8 dB, and more than 10 dB at X-band, respectively. The results of measurement agree well with the simulation. [ABSTRACT FROM AUTHOR]

In this letter, a simple approach to design a reconfigurable feeding network (RFN) for antenna array beam scanning is presented. By combining a 3 dB power divider and a reconfigurable delay line group (RDLG), the two output signals with 2 m+n sets of uniformly distributed phase gradients (PGs) can be obtained. And by adopting multi two-output RFNs and multi-stage design, a RFN for generating 2 m+n continuously distributed beams is constructed. For verifying the design method, a microstrip four-output RFN for generating four scanning beams is implemented, fabricated and measured. The measured results are consistent with the theoretical analysis, which provides the validity of the design. And the design of the RFN can be used as a candidate of the feeding network for antenna array beam scanning. [ABSTRACT FROM AUTHOR]