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We propose an electrically controlled electromagnetically-induced -transparency-like (EIT-like) metasurface combined with high electron mobility transistor (HEMT). The metasurface can be switched between two states by modulating voltage loaded on the gate of HEMT. Modulation depth of 95.9% and the maximum group index of 213.2 are achieved. This kind of electrical control of slow-wave resulting from EIT-like effect has potential applications in terahertz communications.

Considering the shortcomings of the existing vehicle-to-vehicle (V2V) communication antennas, this paper proposes a regular hexagon broadband microstrip antenna. By loading shorting pins and etching V-shape slots with different size at each angle of the regular hexagon patch, it realizes impedance matching and obtains better impedance bandwidth. The simulated results show that the relative bandwidth of this antenna reaches 35.55%, covers the frequency band of 4.74 GHz to 6.79 GHz. The antenna acquires an omni-directional radiation pattern in the horizontal plane whose out of roundness is less than 0.5 dB. In addition, the antenna is manufactured and tested, whose tested results are basically consistent with simulated results. Because the height of antenna is 3 mm, it is easy to be hidden on roof of a vehicle for V2V communication.

Given the flaws in traditional cascading design of the filtering antennas, a kind of filtering antenna based on the defected ground structure (DGS) is proposed. It adopts the method of co-design to integrate the filter and the antenna into one substrate, resulting in a miniaturized size of 34 mm×30 mm. In the design, the structure with dumbbell shape is etched on the ground of dual-band antenna, aiming for the low-pass property of the filtering antenna. The simulated results show that the filtering antenna's co-design can effectively enlarge the bandwidth of the pass-band and suppress the bandwidth of T-patch, whose pass-band can cover the bandwidths of wireless local area network (WLAN) 2.4 GHz, wideband code division multiple access (WCDMA) 2.1 GHz, long term evolution (LTE) 2.3/ 2.5/ 2.6/ 2.8 GHz etc. In addition, the filtering antenna's physical module is fabricated and measured, whose test results are basically consistent with the ones of simulation. Moreover, the filtering antenna with liner polarization has a good radiation pattern of omni-direction, and can be applied to the terminals of wireless mobile system.

According to the differences between the white LED spectrum and the visible light spectrum,the feasibility of using optical coating to improve the spectrum is discussed.Meanwhile,a novel method is proposed to eliminate blue band of the white LED spectrum.The transmittance of the required optical coating is calculated,and the feasibility of method is analyzed.According to the spectrum of the single LED is different at the different temperatures,the transmittance of the required optical coating is calculated based on the spectrum of the single LED at the temperature 4.9°,24°,49°,and the feasibility of using optical coating to improve the temperature stability of the single LED spectrum is analyzed.The results show that the method of using optical film coated on the LED chip does not improve the structure of the white LED to make it similar with the visible light spectrum.The blue band of the white LED spectrum can be eliminated and improve the comfort of the spectrum using the designed optical thin film.The center wavelength and the relative luminous of the analyzed single LED can be stabilized at the 700 nm and 0.2 at the temperature 4.9°,24°,49° using the designed optical film.The similarity of the spectrum at the different temperature is improved greatly.The results contribute to the further application of LEDs.