In this letter, dual band negative group delay circuit (DBNGDC) utilizing a couple of one quarter guided wave length ( truenormalλnormalg4) open circuited stubs (OCSs) is presented. The centre frequencies ( f01,2) are fully controlled with the stub lengths. On the other hand, the target negative group delay (NGD) is obtained using couple of resistors ( R1,2) that connect each OCS to the main microstrip line. The designed DBNGDC accomplishes 52% size diminution compared with smallest size has ever been achieved before. Moreover, 0.2 and 0.4 GHz zero‐NGD bandwidths (BW) are achieved.

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In this article, we demonstrate how the constitutive relations for the nonlinear modeling of hetro-junction bipolar transistors (HBTs) can be based on an artificial neural network (ANN) model representation.. The model is implemented using a commercial microwave simulator, and has been validated by DC and nonlinear measurements. Excellent agreement is obtained as compared with the results of the DC measurements, and the model predicts well the higher-order harmonics in a single tone test.

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In this paper, a 1:11 unequal microstrip Wilkinson power divider (WPD) is presented. Power division is a necessary function in most of the wireless/wireline communication systems. To design 1:11 WPD using an easy-to-fabricate microstrip technology, microstrip line having a very high characteristic impedance (Z c ) value of 315 Ω is needed. Realization of this value is impractical because too thin line is required. Defected ground structure (DGS) provides the hosting microstrip line with high inductance and modest capacitance values simultaneously. As a result, very high impedance could be implemented using practical lines. Novel analytical calculation method is developed to compute Z c of microstrip line loaded with DGS. It is found that circular-patterned DGS could be used to realize the required microstrip line. The designed WPD is fabricated and measured at centre frequency (f c ) equals 1 GHz. The measurements of insertion and reflection losses of the fabricated circuit as well as the isolation between the output ports are in a good agreement with the simulated responses of the designed circuit.