Development of broadband forward‐wave directional couplers loaded by periodic patterned ground structure |
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| Authors: | Zahra S. Tabatabaeian Mohammad H. Neshati |
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| Affiliation: | Electrical Department, Ferdowsi University of Mashhad, Mashhad, Iran |
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| Abstract: | In this paper two wideband Forward‐Wave Directional Couplers (FWDCs) with 0 dB and 3 dB coupling level are proposed. Using periodic patterned ground structure in a microstrip coupled lines by a new unit cell; even‐ and odd‐mode characteristic impedances of the couplers are equal over a wide frequency range. Moreover, it provides a constant phase difference between even and odd‐modes. The proposed cell is modeled using the equivalent circuit model and a design procedure is introduced for designing FWDCs for an arbitrary value of coupling level. The introduced couplers are numerically investigated and a prototype of both couplers is made. It is shown that for 0 dB coupling level, the measured coupling is 0.85 dB with 1 dB flatness over fractional bandwidth of 96% bandwidth. In case of 3 dB coupling, the measured coupling level is 3.5 dB at 7.42 GHz with 1 dB flatness over fractional bandwidth of 67.1%. |
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| Keywords: | composite right/left hand directional coupler microstrip coupled line |
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