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In this letter, a design of broadband microstrip three‐way directional coupler (TWDC) is presented. The broadband performance of the microstrip TWDC is realized by the method of cascading multi‐section. The broadband TWDC is designed to achieve equal power division and −120°, 0°, and +120° phase differences between output signals. To verify the broadband design, a prototype of three‐section microstrip TWDC operating at C‐band is designed, fabricated and measured. The measured results show that the power division error of the designed broadband TWDC is less than ±0.7 dB and phase error is less than ±12° at a relative bandwidth of 16%. To verify its performance in multibeam application, the designed TWDC is used as a beamforming network for multibeam antenna array to generate three orthogonal beams. [ABSTRACT FROM AUTHOR]

This letter presents a wideband high gain substrate integrated waveguide horn antenna (SIWHA) loaded with half Maxwell fish‐eye (HMFE) fabricated by 3‐D‐Printing. The impedance bandwidth of the SIWHA is narrow, mainly caused by the discontinuity between the substrate with the air. By introducing the HMFE and a match layer between the SIWHA with HMFE, the impedance continuity can be realized, which can not only improve the impedance bandwidth but also enhance the antenna gain. Experimental results show that the proposed antenna can achieve more than 6 dBi gain and 60.9% relative impedance bandwidth with reflection coefficients lower than −10 dB. [ABSTRACT FROM AUTHOR]

A design of planar dual‐polarized differentially fed multibeam patch antenna array (DFMPAA) is presented in this article. The dual‐polarized DFMPAA is composed of two circular 4 × 4 butler matrixs (BMs) and a 1 × 4 dual‐polarized patch antenna array. The two BMs are designed in the top and bottom layer as the feeding network of horizontal polarization (HP) and vertical polarization (VP), respectively. The patch is designed as the radiation element of the dual‐polarized DFMPAA, which is fed by the slot and aperture coupling to generate the HP and VP wave, respectively. To achieve high cross‐polarization discrimination (XPD), the antenna element is fed differentially. A prototype working at 5.5 GHz is fabricated and measured in order to validate the performance of the proposed dual‐polarized DFMPAA. The dimension of the dual‐polarized DFMPAA is 3.8 λ0 × 1.7 λ0. Measured results show that when the beam scan to the maximal pointing angle, the XPD of the dual‐polarized DFMPAA in HP and VP are higher than 27 and 29 dB, respectively. Additionally, the beams of the dual‐polarized DFMPAA can cover the range of ±42° in horizontal plane. [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]

In this paper, a wide-range leaky-wave antenna with fast scanning rate and open-stopband (OSB) suppression based on microstrip spoof surface plasmon polaritons (MSSPPs) is proposed. First, the high-scanning-rate theory is analyzed. And based on the theory, the MSSPPs is used to radiate the fan beam rather than quasi-omnidirectional beam. In order to suppress the OSB, a capacitive slot is introduced using the proposed method of impedance matching. The prototype of the proposed antenna is fabricated and the measured results show that the antenna has 140° scanning range from −72° to 68° with the scanning rate of 8.8 and reflection coefficient lower than −10 dB in 8.7–10.2 GHz. [ABSTRACT FROM AUTHOR]