In this communication, a novel hybrid decoupler is proposed to reduce mutual coupling for an extremely compact wideband stacked patch MIMO array antenna. The hybrid decoupler consists of a dielectric surface and a metasurface. By using a well-designed dielectric surface, the mode of mutual coupling current on the unexcited antenna can become orthogonal to its polarization mode. Moreover, the electrical distance of coupling wave propagation between two elements is prolonged. Antenna decoupling is naturally achieved. Then, the metasurface, which can reject coupling wave propagation, is a complementary method to further improve isolation. Dielectric rod array is designed by partially hollowing the dielectric surface, which can realize optimized dielectric constant of slab and better combine two decoupling methods. A broadband stacked patch array antenna is chosen as a demonstration to prove that this idea can achieve wide isolation improved bandwidth, as well as high isolation improved degree. Measured results reveal that isolation enhancement ranges from 6 to 21 dB in the frequency band from 1.83 to 2.17 GHz.

In order to compensate for amplitude inconsistencies of components and circuits, the equalizer has been proposed and introduced. In the previous reports, the theory of equalizer is mainly based on the resonant circuit. In this article, the substrate integrated waveguide (SIW) equalizer fabricated on a ceramic substrate with surface resistance, operating in a millimeter- wave band, is presented first. The key point for SIW equalizer is the introduction of surface resistance instead of the copper layer in a particular location. The working principle of SIW equalizer is discussed in detail. Then, the design method and the procedure are given and demonstrated. A good agreement between the measurement and the simulation indicates its excellent performances. For measurement results, the return losses are better than -18.8 dB for the SIW equalizing values of 2.8, 5.6, and 9 dB over the whole Ka-band. Based on the previous analysis of SIW equalizer, an extensible application in SIW attenuator operating in a millimeter- wave band has been presented first. Measurement results show that the attenuation levels of 5.45 ± 0.15, 10.6 ± 0.4, 21 ± 1, and 30.75 ± 1.45 dB have been achieved in a band of 24.8-38.4 GHz. Besides, the return losses are better than -20 dB in the same frequency band.

A full Ka‐band right‐angle transition from a substrate integrated waveguide (SIW) to an air‐filled rectangular waveguide is proposed. A two‐step ridged waveguide and the SIW with an etched slot are jointly designed to obtain a better electric field and impedance matching between the SIW and the air‐filled rectangular waveguide. To verify the method, a back‐to‐back transition prototype at Ka‐band is designed, fabricated and measured. The measured results show that the insertion loss of a single transition is <0.55 dB over the entire Ka‐band from 26.5 to 40 GHz. Moreover, the 15 dB fractional bandwidth is increased from 25.7 to 40.9% compared with conventional right‐angle SIW‐to‐waveguide transition. This broadband transition can be a good candidate for broadband millimetre‐wave applications.

A novel wideband and compact water antenna with optically transparent characteristic is presented in this communication. This antenna mainly consists of a fan-shaped cylindrical radiator, a top disk, a cylindrical base, and a water reflector. Based on two resonant modes, this antenna can achieve wideband characteristic. Meanwhile, when combined with fan-shaped radiator and top disk loading, the overall dimensions can be greatly reduced without compromising impedance matching. The ground made of distilled water is used for full transparency. The proposed antenna covers frequency range from 1.16 to 2.79 GHz for $S_{11} < -10$ dB. As far as we know, the proposed antenna shows the widest relative bandwidth (82.5%) in the field of transparent antennas, without sacrificing size and radiation performance.

Aiming at the problem of network congestion and unbalanced load caused by a large amount of data capacity carried in elephant flow in the data center network, an elephant flow detection method based on SDN is proposed. This method adopts the autodetect upload (ADU) mechanism. ADU is divided into two parts: ADU-Client and ADU-Server, in which ADU-Client runs in the host computer and ADU-Server runs in the SDN controller. When the host sends the elephant flow, the ADU-Client generates a packet with forged source IP address and triggers the Packet_in message of the edge switch to report the information of the elephant flow to the SDN controller and the ADU-Server completes the elephant flow identification. Experimental results show that the ADU elephant flow detection mechanism can effectively detect elephant flow in the data center network, reduce detection time, and improve network performance.

A broadband transition between a suspended stripline (SSL) and a rectangular waveguide is presented. To improve the bandwidth of the transition, a U‐shaped patch is introduced. A back‐to‐back transition prototype has been designed and fabricated for purpose of verification. Experimental results show that the transition has an insertion loss of less than 0.26 dB and a return loss better than 18.5 dB over the entire Ka‐band (26.5–40 GHz), which agrees well with the simulated results. As compared with the SSL‐to‐waveguide transition using a reduced‐height waveguide, the fractional bandwidth is increased from 29.5 to 40.9%. Moreover, with the reduced‐height waveguide removed, the circuit structure has been simplified. The proposed transition provides a good performance while maintaining a simple circuit structure.