Browsing by Subject "Monopole antennas"

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    Highly directional resonant antennas built around photonic crystals
    (IEEE, 1999) Özbay, Ekmel; Temelkuran, Burak; Bayındır, Mehmet; Biswas, R.; Sigalas, M. M.; Tuttle, G.; Ho, K. M.
    We report a photonic crystal-based resonant antenna with a very high directivity and gain. The layer-by-layer dielectric photonic crystal we used in our experiments was designed to have a three dimensional band gap with a mid-gap frequency around 12 GHz. We used the output port of a microwave network analyzer and a monopole antenna to obtain EM waves. The input port of the network analyzer and a standard gain horn antenna were used to receive the radiated EM field from the monopole antenna. The receiver was kept free to rotate around the antenna. We investigated the radiation characteristics of this monopole antenna, which was inserted into the planar defect structures built around a photonic crystal that consisted of 20 layers. The planar defect was formed by separating the 8th and 9th layers of the structure. In order to suppress the radiation in the backward direction, we intentionally chose one of the mirrors of the cavity to have a higher reflectivity (/spl sim/18-20 dB) than the front mirror.
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    Microwave applications of photonic band gap structures
    (IEEE, 2000-10) Temelkuran, Burak; Bayındır, Mehmet; Özbay, Ekmel; Biswas, R.; Sigalas, M. M.; Tuttle, G.; Ho, K.-M.
    We have investigated two major applications of photonic band gap materials. We demonstrated the guiding and bending of electromagnetic waves through planar waveguides built around layer-by-layer photonic crystals. We then investigated the radiation properties of an antenna that was formed by a hybrid combination of a monopole radiation source and a cavity built around the same photonic crystal structure. © 2000 IEEE.
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    Radiation properties and coupling analysis of a metamaterial based, dual polarization, dual band, multiple split ring resonator antenna
    (Taylor and Francis, 2012-04-03) Alici, K. B.; Serebryannikov, A. E.; Özbay, Ekmel
    We demonstrate an electrically small antenna that operates at two modes, which correspond to two orthogonal polarizations. The antenna was single fed and composed of perpendicularly placed metamaterial elements and a monopole. One of the metamaterial elements was a multi split ring resonator (MSRR), and the other one was a split ring resonator (SRR). The elements' physical sizes were the same while the electrical sizes differed nearly by 1 GHz. This variety resulted in the dual mode operation at the 4.72 GHz and 5.76 GHz frequencies. When the antenna operated in the MSRR mode at 4.72 GHz for one polarization, it simultaneously operated for the SRR mode at 5.76 GHz, but for the perpendicular polarization. The efficiencies of the modes were 15% and 40%, and electrical sizes were λ/11.2 and λ/9.5, correspondingly. Finally, we numerically demonstrate the effect of coupling of the two resonators on the operation frequencies.