An Equivalent Circuit for Discontinuities Exciting Evanescent Accessible Modes

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Abstract-In this paper, a technique to identify/synthesize an equivalent circuit of nonreciprocal lossy N -port device is presented. The technique joins the classical procedure discussed in the '60s to the polygon network recently proposed in the literature, which permits to draw an equivalent circuit for reciprocal lossless N -port device in a very simple way. The identification is applied to two microwave devices, a reciprocal lossy iris in WR90 waveguide and a 3-port nonreciprocal lossy circulator. The proposed equivalent circuit could give some information about the agreement of the manufactured device and its design, which usually is developed in the hypothesis of ideal lossless components.

Section: Introductionmentioning

confidence: 99%

Identification of Equivalent Circuit Based on Polygon Network for Nonreciprocal Lossy N-Port Device

Zappelli¹

2017

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“…The proposed circuit for a 4-port device is shown in Fig. 1(a), and it is derived from the equivalent circuits discussed in [22][23][24][25]. The transformers are used to normalize the admittances in the circuit kernel.…”

Section: Equivalent Circuit Approach (Ec-approach)mentioning

confidence: 99%

“…In the past, the author has defined some equivalent circuits to represent the presence of evanescent accessible modes and a fast and simple method for the identification of the electrical parameters of the equivalent circuits for waveguide devices [22][23][24][25]. Hence, in the second approach an equivalent circuit will be proposed to reconstruct the N -port S-matrix waveguide device, starting from 2-port VNA measurements, in order to minimize and simplify the evaluation of its N (N + 1)/2 circuit parameters.…”

mentioning

confidence: 99%

Reconstruction of the S-Matrix of N-Port Waveguide Reciprocal Devices From 2-Port Vna Measurements

Zappelli¹

2017

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Abstract-Two approaches to reconstruct the S-matrix of N -port waveguide reciprocal devices from 2-port S-matrix measurements are proposed and discussed. The main advantage of the proposed approaches is that measurements are done always at the same two ports, without moving the device. The remaining N -2 ports are loaded with different loads, either matched or short. The first approach, based on a manipulation of the 2-port S-matrices, requires N -2 matched and two other loads, while the second approach, based on the evaluation of an equivalent circuit, requires N -2 short and two other loads. The measurement technique is based on standard loads (short, shift and matched) in the waveguide calibration kit of the 2-port VNA.

“…Recently, an accurate equivalent circuit representing the effect of a discontinuity on the propagating and evanescent accessible modes has been proposed [7]. In this equivalent circuit, which can easily be drawn for any numbers of ports (modes), unlike other recently discussed equivalent circuits [8], an evanescent mode is represented by an evanescent line of electrical length θ connected with a series reactance equal to the conjugate of the modal (reactive) impedance and a transformer that links the modal port to the "core" of the circuit, based on an n-sides polygon with susceptances placed on every side and diagonal.…”

Section: Introductionmentioning

confidence: 99%

“…The equivalent five-port circuit for a discontinuity with one input, one output propagating mode (ports 1, 2) and three output evanescent modes (ports 3, 4, 5) [7].…”

Section: Introductionmentioning

confidence: 99%

Circuit Approach to the Analysis of Microwave Discontinuities

Zappelli

2013

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Abstract-An equivalent circuit based on propagating and evanescent accessible modes is discussed and the numerical values of its elements (susceptances and electrical length) are obtained starting from the knowledge of the generalized scattering matrix S of microwave discontinuities. A database of the circuit elements is then defined in the frequency and geometric ranges of the analyzed discontinuities and is used to evaluate the generalized scattering matrix for values not contained in the database, with very simple formulas for any number of circuit ports. The obtained S matrices can be used to analyze very complex structures such as iris-based filters and manifold filters.