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In this paper, a wide stop-band microstrip coupler is presented . The proposed structure consists of coupled lines and step impedance cells, which are integrated to operate at 2.82 GHz… Click to show full abstract
In this paper, a wide stop-band microstrip coupler is presented . The proposed structure consists of coupled lines and step impedance cells, which are integrated to operate at 2.82 GHz for wireless applications. This coupler is formed by a symmetric structure so that the locations of the output ports relative to input are quiet similar. Accordingly, the magnitudes (also phases) of S 21 and S 31 overlap each other so that input signal can be selected through the output ports equally. There are little differences between the magnitudes and phases of S 21 and S 31 so that 0.97˚ phase shift is obtained. In comparison with previous works, the performance of the introduced coupler is improved. To get a better isolation, return loss and harmonic attenuation the frequency response is optimized without significant increase in circuit size. Moreover the first, second and third harmonics of S 21 and S 31 are well attenuated as well as a wide stop-band is obtained up to 15.1 GHz. The realized coupler is fabricated and measured. There is a good agreement between simulated and measured results, which confirms the design process.