WR-Connect

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Design Editor


1.Controls and Forms


The Design Editor is realized on Editor Page (see Figure 1) with local URL “editor.htm”. It is a dynamic HTML webpage with multiple controls, forms and drop-down menus.



Figure 1: Design Editor screenshot


All those control elements are associated with the design concept and its EM model (elements, modal settings, filling) and geometric dimensions (length, width, height and position of each element). There are the following controls:


2.Drop-Down Menus


The Design Editor is also equipped with three drop-down menus from the Main Menu black bar (located on the top of the WR-Connect pages).


3.Structure Profile


A)Design Editor Methods


WR-Connect utilizes a simple and unique way of representing a design concept in terms of text lines. This approach differs from common design tools, which represent a EM structure as a network of symbols (AWR, Mician, FEST-3D) or 3D drawings (HFSS, CST). WR-Connect EM structure representation is realized as a plain text file, which is closer to old-fashioned software like Touchstone, but much simpler and more efficient. Despite its visual inconvenience, this method has multiple advantages in design operations (easy connecting, removing, inserting and correcting the single elements and parts of structure) as simple text edition operations (pasting, cutting, copying, replacing).


B)EM Structure Representation


WR-Connect is applicable to EM structures composed from three types of junction (waveguide component performing incident mode scattering). Each of those junctions represent a solution of EM boundary problem of waveguide scattering realized in variational mode-matching numerical approximation. The solutions express 2x2 GSM versus frequency (frequency domain) characteristics of the following types of connections between two waveguides:

All three types are defined below in more details. The EM solution is based on the variational mode-matching solution (see [1] for details) counting a single incident (accessible) mode and full set of localized modes (set in Solution Modes area). Each of the junctions have 0-length interface. In the other words, the EM solution for the s-parameters does not include the electrical phase of the waveguides connected to the junction from the both ends. For example, a step junction (index 0) of two waveguides includes just the face of their connection and it does not include the lengths of the waveguides (i.e. the junction has zero length). The whole EM structure is composed from those types of junctions, which put sequentially in a cascade and connected by straight waveguide sections. Those waveguides, which are used to connect junctions are called “nodes” here. Only one type of node is used in this version of WR-Connect:



C)Connections Circuitry (Schematic, Topology)


Thus, the structure can be designed from those four elements described above if put in cascade (see Figure 2) according to the connection rules.



Figure 2: EM structure representation as sequential connection of junctions put between nodes


Connection rules are:


Each of the elements in the cascade (see Figure 2) is represented as a single text line in the Structure Profile window, which is written in a certain order and contain records about element type (index), length, XY coordinates of left bottom and right top points of the cross-section rectangle.


D)Reference Coordinate System


The structure dimensions is referenced to a rectangular XYZ coordinate system (see Figure 3) with the centre located at the beginning of the structure (say input port) with the Z axis directed in the direction of the waveguide channel forward to the opposite end (say output port) and parallel to the walls of waveguides. The X and Y axis's lays in the plane of the input face oriented in parallel to the top/bottom and side walls edges respectively.



Figure 3: Reference coordinate system and structure orientation


The centre of the coordinate centre is generally a matter of user’s preference. In case of vertical or/and horizontal symmetry, the coordinate centre must lay on the appropriate symmetry planes. In other words, if our structure is symmetric relatively to the central vertical plane, the Y-axis must lay on the symmetry plane. If, for example, the structure is symmetrical in respect to the central horizontal plane, the X-axis must lay on it.


E)Element Text Line


Each constituent element of the waveguide structure is entered as a single text line record into the Structure Profile text content. The element record contains seven parameters (two keys and five dimensions). The dimensions of the element are defined as shown on Figure 4.


Table 1: Node keys and parameters record order

i

Index

D

X0

Y0

X1

Y1

0.000


The element parameters record contains the following data:


F)Node (Index 1)


The Node is a section of rectangular waveguide, which is defined with the length D and cross-section rectangle given by the coordinates of the left bottom corner (X0, Y0) and right top corner (X1, Y1) if looking at the input aperture (see Figure 4).



Figure 4: A waveguide section (Node) with defined dimensions


The Node element is represented as a single text line in the Structure Profile text content. The text line contains a record of seven parameters and keys in the order shown below in Table 2 below and definitions in section 3E above.

Table 2: Node keys and parameters record order

i

1

D

X0

Y0

X1

Y1


G)Step Junction (Index 0)


The Step Junction (index 0) is a direct (inline uniaxial) connection of two rectangular waveguides (see Figure 5). The both waveguides are defined as Node (index 1). The Step Junction is specified only with index key (index=0) and all other parameters are ignored by the computational algorithm and set to zeros if been updated (see Table 3).


Table 3: Node keys and parameters record order

0

0

0.000

0.000

0.000

0.000

0.000

0.000

Although the Step Junction record does not contain any information it must be presented in the Structure Profile if two waveguide nodes directly connected to each other.



Figure 5: Step junction of two rectangular waveguides. One of the waveguide cross-sections is within or coincide with the other one, but does not crosses its boundaries.



The Step Junction connection is valid if the cross-section of one of the waveguides is within the cross-section of the other waveguide as shown on Figure 5. Some of the boundaries of the rectangles or even all of them, however, may coincide but not intersect (see Figure 6 for example).



Figure 6 : An example of wrong connection when the cross-section area of one waveguide intersects with the cross-section area of the other one

H)Cavity Junction (index 2)


The Cavity Junction is formed as an uniaxial connection of three waveguides (two Nodes (index 1) and Cavity (index 2) between them) as shown on Figure 5 below. Though the junction is formed by two Step Junctions (section 3G) connected to each other with tapered ends, the EM solution differs and it is more accurate, because it counts all “localized” [1] waveguide modes (set as Solution Modes in the Design Editor). Therefore, in case of same waveguide structures representable in different ways (steps, irises, cavities), it is recommended to represent the structure by Cavity Junctions.



Figure 7: A Cavity Junction formed by a waveguide of greater cross-section.


The rules for the positioning of the waveguides relatively to each other are same as in case of the Step Junction from each side. In other words, each of the input Nodes must have a cross-section included into the cross-section area of the Cavity (the nodes boundaries may coincide but do not intersect with boundaries of the cavity). The Cavity Junction record order is shown below:


Table 4: Cavity Junction keys and parameters record order

i

2

D

X0

Y0

X1

Y1

0.000



I)Iris Junction


The Iris Junction is formed as an uniaxial connection of three waveguides (two Nodes (index 1) and Iris (index 3) between them) as shown on Figure 6 below. In vice versa, the cross section area of the Iris must be within the cross-section area of each connecting Node (the boundaries of the Iris window may coincide but do not intersect with boundaries of the Nodes).



Figure 8: Iris Junction formed by a waveguide of smaller cross-section.



The Iris Junction record order is shown below:


Table 4: Cavity Junction keys and parameters record order

i

3

D

X0

Y0

X1

Y1

0.000



J)Structure Profile Content


As it is already mentioned above, a whole waveguide structure is represented as sequence of connections (nodes and junctions). Each of the connection elements is defined with keys and dimensions and identified by a single text line in the Structure Profile (as shown below as example below).


Table 5: An example of Structure Profile text containing 9 lines representing nodes (red) and junctions (blue).

0 1 0.375000 -0.375000 -0.187500 0.375000 0.187500

5 2 0.350000 -0.375000 -0.271257 0.375000 0.271257

1 1 0.192856 -0.375000 -0.100000 0.375000 0.100000

4 3 0.038000 -0.155398 -0.100000 0.155398 0.100000

1 1 0.454410 -0.375000 -0.100000 0.375000 0.100000

4 3 0.038000 -0.208090 -0.100000 0.208090 0.100000

1 1 0.375000 -0.375000 -0.100000 0.375000 0.100000

0 0 0.000000 0.000000 0.000000 0.000000 0.000000

0 1 0.375000 -0.375000 -0.187500 0.375000 0.187500


Same structure is drawn in 3D style looks like as shown on Figure with arrows pointing to the elements from the list in Table 5.



Figure 9: 3D view of EM model corresponding to the textual representation in Table 5


4.Solution Modes


A)Definitions of EM Solution Modes


All (three) E-models of scattering elements (junctions: step, cavity, iris) are based on solutions of appropriate EM boundary problems. A multi-modal variational method (VMM) [2] is applied to the problem of EM scattering on uniaxial junction of three waveguide, with a larger waveguide in the middle (cavity junction) in [1]. In terms of VMM the modal sets included in the solution are divided into two sub-sets, which are the accessible and localized modes accordingly. The accessible modes are the incident waveguide modes, which scatter on the junction from outside (they come from infinity, pass through or reflected to infinity). The localized modes are the sub-set of waveguide modes, which are counted in the solution as orthogonal modal basis. In the other words, it is a modal set used for the matching of EM fields (in mode-matching). It is generally a much greater set of waveguide modes including evanescent modes. The Cavity Junction EM problem is solved in [1] in a rigorous formulation. The solution used in WR-Connect is, however, approximated by a single accessible mode counted. The number of localized modes can be much greater and not generally limited. Nevertheless, it is not recommended to set more than 100-200 solution modes, because it will significantly slow down the simulation with no significant gain of accuracy. The incident mode (accessible mode) and the set of the localized modes can be set manually by appropriate controls in Designer Page (see Figure 10) by three numbers each.


Figure 10: Modal setting controls


The first numbers in the both controls define the type of waveguide mode (0 for TE-mode and 1 for TM- mode). The second number defines the first index (N) in TENM/TMNM mode. The third number defines the second index (M) in TENM/TMNM mode, analogically. The both indexes N and M depend on symmetry settings.


B)Vertical Symmetry YZ


The vertical symmetry is set in YZ-Symmetry options box in the left top corner. It can be specified as no-symmetry (None), H-plane or E-plane. This symmetry key defines the first indexes of the dominant incident mode and the modal set of the solution (localized modes). In a general case of TENM or TMNM modes, the set of first indexes N are defined below.


Table 6: The sequence in the numbering of the first index of the waveguide modes

YZ-Symmetry

Index N in TENM/TMNM modes

None

N= 0, 1, 2, ….., n, …

H-plane

N= 1, 3, 5, …., 2n+1, ….

E-plane

N= 0, 2, 4, …., 2n, ….


C)Horizontal Symmetry XZ


The vertical symmetry is set in XZ-Symmetry options box in the left top corner. It can be specified as no-symmetry (None), H-plane or E-plane. This symmetry key defines the first indexes of the dominant incident mode and the modal set of the solution (localized modes). In a general case of TENM or TMNM modes, the set of second indexes M is defined in the Table below.


Table 7: The sequence in the numbering of the second index of the waveguide modes

YZ-Symmetry

Index M in TENM/TMNM modes

None

M= 0, 1, 2, ….., m, …

H-plane

M= 1, 3, 5, …., 2m+1, ….

E-plane

M= 0, 2, 4, …., 2m, ….



D)Incident TE10-mode Settings


TE10-mode is the first mode in rectangular waveguide and most waveguide components operate on TE10-mode transmission or reflection. Only four of nine symmetry options set TE10-mode (see Table below).


Table 8: The dominant TE10-mode settings under different design symmetries

Symmetry YZ

Symmetry XZ

Type

n

m

None

None

0

1

0

None

E-plane

0

1

0

H-plane

None

0

0

0

H-plane

E-plane

0

0

0



E)Solution Modal Settings


The set of solution modes is defined by the last mode in the set, which, in turn, is also defined by three indexes (type, n, m). In this case, the solution will count all waveguide modes within the symmetry family and with the indexes being not greater. For example, if the structure possesses vertical H-plane and horizontal E-plane symmetries and the solution modes are set as type=1, n=10, 10, it would define a modal set of TENM (type 0) and TMNM (type 1) with odd first indexes (N=1, 3, 5,…,21) and even second indexes (M=0, 2, 4, …, 20) according to Tables 6-7 above.


F)How to Check the Incident Mode Settings


Prior to performing simulations, it is important to have proper modal setting. It can be noted that all conventional waveguide components (excluding the overmoded waveguide applications) operate on TE10-mode scattering. The common (in usual definition) name of the scattered incident waveguide mode is normally displayed on the button (incident mode indicator) located at the bottom of “Incident Mode” entry field. The incident mode indicator, however, is not automatically updated if the modal settings are changed by a user. If the settings are manually changed, the new name of the dominant mode can be found out by clicking the indicator button.


G)Quick Modal Settings


In a general case, a user can start from setting the Incident Mode as TE10-mode (see Table 8). The solution modes could be set as type=1, n=10 and m=10. The advanced users, however, can take advantage of more efficient modal setting (see examples in tutorials).


5.Run Status Controls


The controls are used during simulation and optimization. In the both cases the red status bar will be extending showing the completeness of the process. In same time, the left button located under the status bar will show some numbers related to the process. During an optimization process (performance and space mapping optimizations), the numbers indicate a measure of how the current state is close to the targets. The simulations can be interrupted by the user in any time of the process by clicking the button.


6.Space Mapping Controls


The controls are designed to perform aggressive space mapping (ASM) process step by step. The steps include the following operation:

More information is available about ASM in the tutorials.


7.Design Corrections Controls



To be Continued Soon



[1] F. De Paolis, R. Goulouev, J. Zheng, M. Yu, “CAD Procedure for High-Performance Composite Corrugated Filters”, IEEE Trans. Microw. Theory Tech., vol. MTT-61, No. 9, Sept. 2013


[2] J. W. Tao and H. Baudrand, “Multimodal variational analysis of uniaxial waveguide discontinuity,” IEEE Trans. Microw. Theory Tech., vol. 39, no. 3, pp. 506–516, Mar. 1991.