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Electromagnetic Waves and Transmission Lines for Wearable Communication Systems Designers
Published in Albert Sabban, Novel Wearable Antennas for Communication and Medical Systems, 2017
At this location we can add a shunt stub with normalized input susceptance, −jB¯ to yield Y¯in=1 as presented in Equation 2.60. Y¯in=1 represents a matched load. The stub can be short-circuited line or open-circuited line. The susceptance B¯ is given in Equation 2.60.
Electromagnetic Compatibility for High-Speed Circuits
Published in Xing-Chang Wei, Modeling and Design of Electromagnetic Compatibility for High-Speed Printed Circuit Boards and Packaging, 2017
In a multilayered PCBs, the via stub is the residual part of the through-hole via after the via construction, as shown in Figure 1.48a,b. The via stub can be considered an open-ended transmission line connected in parallel to the signal trace. The stub impedance is frequency-dependent and will change the signal trace impedance at the stub connection. When the stub length is smaller than a quarter wavelength, the stub can be considered a capacitance. When the stub length is about a quarter wavelength (or at the resonant frequency of the stub), due to the impedance transformation of the transmission line, the stub can be considered a short circuit at the stub connection. This will result in large signal reflection, and the stub works like a stopband filter.
Transmission and Propagation of Electromagnetic Waves
Published in Sibley Martin, Modern Telecommunications, 2018
Short-circuited and open-circuited stubs (short lengths of transmission line) are very useful elements for use in transmission lines. Depending on termination, they appear to be inductive or capacitive. Consider the situation in Figure 5.7, which is a simplified version of Figure 5.4. We have a length of transmission line and then a load. The source voltage, Vs, is
Design of Compact UWB Filter Using Parallel-coupled Line and Circular Open-circuited Stubs
Published in IETE Journal of Research, 2022
Parthasarathy Ramanujam, Chandrasekar Arumugam, Ramesh Venkatesan P G, Manimaran Ponnusamy
The simulated passband insertion and return loss are |S21|>–3.4 dB and |S11|>–10 dB, respectively. The performance of the filter is improved further incorporating the rectangular open-circuited microstrip stub lines in the input and output ports as illustrated in Figure 3. It is observed that the roll-off rate, insertion and return loss in the passband are significantly improved compared with Figure 2. The length of the high impedance open-circuited stubs length is λg/4, where λg is the guided wave length calculated at midband frequency f0. Similarly, the rectangular open-circuited stub loaded configuration has enhanced selectivity of 0.542, with passband insertion and return losses of |S21|> –2.05 dB and |S11|> –15 dB, respectively. Further, the passband selectivity of the filter is enhanced significantly by incorporating the circular open-circuited stubs in high impedance parallel open-circuited stubs located at input/out ports. The radius of the stub is obtained using (1) and optimized to enhance the filtering characteristics further. where f0m is the midband frequency (6.8 GHz), R is the radius of the open-circuited stub, t is the width of the high impedance stripline connected with circular stubs, c is the free space velocity. The performances of the presented filter's without stubs, without rectangular stubs and with rectangular and circular open-circuited stubs are compared and it is illustrated in Figure 4.