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Attenuators
Published in John Bird, Newnes Engineering Science Pocket Book, 2012
An image impedance is defined as the impedance which, when connected to the terminals of a network, equals the impedance presented to it at the opposite terminals. For example, the impedance looking into port 1 of Figure 80.12(a) is, say, 400 Ω when port 2 is terminated in, say 750 Ω, and the impedance seen looking into port 2 (Figure 80.12(b)) is 750 Ω when port 1 is terminated in 400 Ω. An asymmetrical network is correctly terminated when it is terminated in its image impedance. (If the image impedances are equal, the value is the characteristic impedance).
Design of Low Profile Cylindrical Conformed Microstrip Patch Antenna for Wideband Operation
Published in IETE Journal of Research, 2021
Sandeep Kohar, Surinder Singh, Asok De
An MPA is actually an open resonator bounded by two electric walls at the top and the bottom. Hence the truncated ground plane under the patch will definitely perturb the excited EM fields. The ground plane serves as the bottom boundary and as such a defect on the microstrip line feeding a microstrip patch may be regarded as a two-port device whose image impedance can easily be controlled by placing a defective ground below it [21]. The dimensions of the defective ground modify the effective inductance and capacitance of the line and thus may help in achieving proper impedance matching.
A Compact Dual-Band Bandpass Filter Using Coupled Microstrip Lines
Published in IETE Journal of Research, 2022
R. Salmani, A. Bijari, S. H. Zahiri
It should be noted that the mode impedance and mode-voltage ratios can be found by the width of W1 and W2 and the gap spacing of S1 [19]. By assuming θoo = θee = π/2 and comparing the image impedance and propagation constant of the symmetric three coupled-line with its equivalent circuit, the mode impedances of Zoo and Zee are obtained as follows: