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A symmetrical lattice is a two-port electrical wave filter in which 'diagonally-crossed' shunt elements are present, a configuration which sets it apart from the familiar ladder networks. The component arrangement of the lattice is shown in the diagram below. The filter properties of this circuit were first developed using image impedance concepts but, later, the more general techniques of network analysis were applied to it. There is duplication of components in the lattice network as the "series impedances" (the Za's) and "shunt impedances" (the Zb's) both occur twice, but the arrangement offers great flexibility to the circuit designer, with a variety of responses achievable. For example, it is possible for it to have the characteristics of: a delay network,〔Weinberg L., "Network Analysis and Synthesis", McGraw Hill 1962, (p. 633)〕 an amplitude or phase correcting network,〔Stewart J.L., "Fundamentals of Signal Theory", McGraw Hill, 1960, (p. 138)〕 a dispersive network 〔Cook C.E. and Bernfeld M., "Radar Signals", Artech House MA, 1993, ISBN 0-89006-733-3, (p.413)〕 or as a linear phase filter,〔Guillemin E.A., Communication Networks, Vol II", Wiley N.Y., 1935〕 according to the choice of components for the lattice elements. == The Lattice Configuration == The basic configuration of the symmetrical lattice is shown in the left-hand diagram and a commonly used short-hand version is shown on the right. In the simplified version, dotted lines are used to indicate the presence the second pair of matching impedances, to give a less cluttered schematic. center It is possible with this circuit to have the characteristic impedance specified independently of its transmission properties,〔Zverev A.I., "Handbook of Filter Synthesis", Wiley N.Y., 1967, (p.6)〕 a feature not available to the familiar ladder filter structures. In addition, it is possible to design the circuit to be a constant resistance network for a whole range of circuit characteristics, The lattice structure can be converted to an unbalanced form (see below), for insertion in circuits with a ground plane. There are other benefits from doing the conversion, one is the reduction of the component count and another is the relaxation of component tolerances.〔Bode H.W. , “Network Analysis and Feedback Amplifier Design”, Van Nostrand, N.Y., 1945〕 It is possible to redraw the lattice in the familiar Wheatstone bridge configuration,〔Campbell G.A., “Physical Theory of the Electric Wave-Filter”, BSTJ, Vol. I, No. 2, Nov. 1922, (pp.1-32).〕 as shown in the article Zobel network. However, this is not a convenient format in which to investigate the properties of lattice filters, especially their behavior in cascade, so it is not used in articles on filter design. 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「Lattice networks」の詳細全文を読む スポンサード リンク
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