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In this letter, a 180° ring-shaped hybrid based on the photonic crystal structure (PCS) is presented. The ring hybrid is designed for the operation wavelength of 1550 nm. Initially, a 180° hybrid is a design based on conventional microwave procedures. Different wave behavior inside the structure in THz and microwave frequency band has caused the wave propagation in this structure to change especially in terms of phase. By analyzing the field distribution within a structure, the rod arrangement is modified. In proposed structure, the phase difference between the output ports is greatly improved (about 90°). Also, by reducing the leakage and improving the matching, the output power of the ports tends to half power. Moreover, 32 nm wavelength shift is improved. The proposed structure’s reflectance value is less than 20 dB at the desired wavelength. The power splitting ratio between the two output ports is improved up to −3.7 dB and the power of the isolated port is less than −20 dB. This work has been analyzed using the FDTD method. [ABSTRACT FROM AUTHOR]

Characteristics of flat symmetric antenna of axial radiation 150 mm long with linearly extending aperture for angels of the aperture 30˚, 60˚ and 90˚ were studied. Thus directional diagram of antennas have been theoretically calculated, experimentally measured and analyzed, is revealed that characteristics of experimentally measured directional diagram well will be agreed with the developed mathematical models in the range of the frequencies of 5,9-12,5 GHz. On the obtained experimental data dependence of coefficient of the directed operation of the studied antennas on an angel of a aperture is revealed.

Characteristics of symmetric planar slot antennas of axial radiation, the size of which is comparable with the radiation wavelength ( = 30 mm) having a linearly extending opening was studied. The same directional diagram investigated antennas have been theoretically calculated, experimentally measured and analyzed for Aperture angle of 30, 60, 90 and 120. Experimentally measured directional diagram of the antennas (at frequencies of 10 GHz) are in good agreement with the developed mathematical models.