User Manual Mstrip40

Prof. Dr. Georg Splitt

Fachhochschule Kiel, Fachbereich Elektrotechnik,
Institut fuer Nachrichtentechnik und Elektronik,
Legienstrasse 35, 24103 Kiel, Germany,
Tel: /4322/699623, Fax: /4322/699624

Last Modified: 5.9.2000

software and manual copyright (c) 2000 by Prof. Dr. Ing. Georg Splitt
All rights reserved

1. INTRODUCTION
2. FEATURES AND RESTRICTIONS OF THIS VERSION
2.1 Future features
2.2 Reported Problems
3. SYSTEM REQUIREMENTS
4. GETTING STARTED
4.1 Installing the program

4.2 Calling Mstrip40 the first time
4.3 Viewing the example files
4.3.1 Viewing the current distribution

4.3.2 Viewing the radiation pattern
4.3.3 Viewing the input impedance
5. HOW TO USE THE PROGRAM
5.1 Main menu and the Format of the input files *.str
5.1.1 Defining general parameters

5.1.2 Defining the geometry of the structure
5.1.3 Excitement of the structure
5.1.4 Different segment sizes
5.1.5 Multiple layers
5.1.6 Slot coupling
5.1.7 Multiple ports
5.1.8 No ground option
5.2 Calculating the reaction integrals
5.3 Iterative analyzing of the structure
5.4 Batch calls
5.5 Controlling precision of computation
6. CHANGES SINCE LAST VERSION
7. COMMENTS
8. REFERENCES
9. LIST OF EXAMPLES (DEMO FILES)
10. UPDATES, MORE INFO

1. INTRODUCTION:

The MultiSTRIP program is written to analyze and design multilayered arbitrary shaped microstrip antennas on multiple dielectric layers.

The solution is done by rigorous solution of integral equation via Galerkin Method (Moment Method) and using the correct Greens functions. Therefore all relevant effects like radiation, surface waves propagating in the substrate and dielectric losses are taken into account.
Those rigorous methods have been usually restricted to mainframe computer systems or at least powerful workstations. Implementation on small PC's is difficult due to large computation time and large memory requirements.
Especially the calculation of the coupling integrals (reaction integrals) for the used basis functions to approximate the current is very time consuming. This problem is overcome by using combined integration techniques in conjunction with closed form subtraction of asymptotic parts of the integrand or suitable deforming of the integration path.
The next problem is the solution of the resulting linear system which becomes too large to fit into the memory of a small computer. By using iterative techniques for solving the linear system the required memory and computer time is dramatically decreased even for large structures.
The program is originally written for microstrip antennas but is also capable to deal with arbitrarily shaped multilayered microstrip structures. The method shows usually a very precise agreement between theory and experiment.
For the interested user details are found in the references [1-5].
The program is written in C++, MFC and Fortran77 with Watcom compiler 10.6; the calculation modul Ms_calc.exe is compiled with Digital Visual Fortran
This program is provided AS IS without any warranty, expressed or implied, including but not limited to fitness for a particular use.

2. FEATURES AND RESTRICTIONS OF THIS VERSION:

2.1 Future Features:

2.2 Reported Problems:

3. SYSTEM REQUIREMENTS:

4. GETTING STARTED:

4.1 Installing the program

Recommended installation hints for Mstrip40 windows95 version:

1) copy (extract) all directories to your harddisk, use the same name of
   directory ( c:\mstrip40):

          Mstrip40.exe    Main program
          Ms_patte.exe    shows radiation pattern
          Ms_curre.exe    shows current distribution
          Ms_smith.exe    shoes input impedance
          MS_layer.exe    analyzing a dipol in multilayered structure (under construction)
          Ms_calc.exe     calculation module (number cruncher, does the work)
          MsDongel.exe    Program for installing the Dongel (Saftykey)

   following subdirectories:

          mstrip40\data     contains example files
          mstrip40\manual   contains manual in Html format

   following file should be copied to c:\windows or c:\winnt

          mstrip40.ini

2) in case of using a fullversion with Dongel (Saftykey) execute
   MsDongel.exe and following instructions.
   After installing reboot the PC even your computer dont tell you!!

3) call the main modul Mstrip40, place the icon to the desktop

4) For using your favorite Editor and Html Browser modify the file Mstrip.ini
   in the windows directory:

EditorName=notepad.exe
HtmlName=(fullpathbrowser) C:\mstrip40\manual\manual.htm

The manual is written in html format, therefore any freeware html
browser (netscape) can be used. You might modify the path for your
browser in the the mstrip.ini file.

This is version 1.3, dont expect a perfect program. Error reports
and any comments would be gratefully appreciated by the author.
Technical support and improved versions of the program will
be provided in return as work progresses.

This program is provided AS IS without any warranty, expressed
or implied, including but not limited to fitness for a particular use.

For Updates contact author or download from: http://intek.e-technik.fh-kiel.de/Splitt.htm

4.2 Calling Mstrip40 the first time

Call the main module Mstrip40 by clicking on the Icon and the following screen should appear:

Mstrip40 window

For the first time press the menu item "Options" and choose your favorite editor. In case you chose a different directory for the programs then recommended you also have to edit the file Mstrip40.ini. Add or modify the line ProgramPath=c:\MSTRIP40\ to this directory where you program is located.

Move the mouse and the Help/Status line will explain any button and item in the window.

4.3 Viewing the example files

For the first time you should see the data of the file "Demo1.str". You can choose an arbitrary structure file with . The most relevant dates are displayed in the main window. However all dates are maintained in the structure files (*.str). To edit the structure file press . With the button . you obtain a more detailed view of the segmented structure. The antenna is already analyzed (Data is in file demo1.rea and demo1.slv). Therefore there is no need to press jet, which would start calculation procedure of the structure.

4.3.1 Viewing the current distribution

Please press . This will start the module Ms_curr.exe to display the current distribution as a color plot and by pressing 3d you will see the current distribution flowing on the patch antenna in a three dimensional presentation:

. .

With the arrow keys the view angle of the three dimensional presentation is changed. The lower left corner shows the view angle theta, phi. Pressing the numbers "1,2","3,4" etc. selects the structure (or layer) to be viewed (demo1 has only one structure, see chapter 5.1.5). Pressing (next) or <PREVIOS
Close the current window to return to the main module Mstrip40.

4.3.2 Viewing the radiation pattern

The button . stands for pattern and allows to analyze the radiation pattern. The first call shows a polar 3d pattern at the first frequency point. The Co polarization is coded in colors. With the item "Right, Left .." the view of the three dimensional pattern is changed. The lower left corner shows the view angle theta and phi. With the menu item "Kos" you can switch the coordination system and additionally display a 2d cut of the pattern:

. .

The menu item "Info and Control" displays an additional window for setting desired frequency point and polarisation state. The displayed polarization can be changed between linear and circular and between magnitude, co- and cross. The Co component is defined as E_Theta for linear /E_RH (Right Hand) for circular/ polarization and the Cross component as E_Phi /E_LH (Left Hand)/ polarization, respectively. The definition of the linear Co and Cross components might be changed in accordance to the third definition of reference [13, Ludwig] by choosing LUDWIG.

The lower left part displays the maximum directivity together with the corresponding angle of the direction at the maximum and the radiation efficiency. However, this option is not fully evaluated jet (use with caution and only in conjunction with high precision calculation).

With typing "create .pat file" a file name.pat is created for the chosen frequency point. It contains the three dimensional radiation pattern in a format described below: 

Phi cuts, Theta values per cut, gain, efficiency, wavelength        
PhiStart           
ThetaStart, Co, Cross, Phase of Co, Phase of Cross     
... 
... 
ThetaEnd, Co, Cross, Phase of Co, Phase of Cross     
... 
... 
... 
PhiEnd 
ThetaStart, Co, Cross, Phase of Co, Phase of Cross 
... 
... 
ThetaEnd, Co, Cross, Phase of Co, Phase of Cross
The Co and Cross components are given in [dB] and Degree. The Co (Cross) component correspond to either E_Theta (E_Phi) for linear polarization, E_x (E_y) in accordance to [13, Ludwig] or E_RH (E_LH) for circular polarization. The preset of linear polarization in the program might be changed by Keyword "LUDWIG" or "CIRCUL" in the structure file, see 5.1.1.

4.3.3 Viewing the input impedance and scattering parameters

By pressing . for smith diagram a more detailed diagram for the input impedance is displayed:

.

With the menu item "Control" and or "Table" you can choose the desired frequency point and watch the corresponding scattering parameter in amplitude, dB and phase (s11, s12, s13 .... s19), see chapter 5.1.7. In case of using the keyword EXCITE (therefore all ports are excited with different amplitude) the Window 3 represents the active input impedance (rho1, rho2 ......rho9), see chapter 5.1.7..

5. HOW TO USE THE PROGRAM

The Program Mstrip works together with five types of data files (*.str, *.rea, *.slv, *.snp, *.pat).

All dates of the structure are given in the input file *.str which has to be edited in advance or within the program by pressing , see chapter 5.1. Interactive change of the input data by the calculation program Ms_calc is avoided to allow also a batch call (see chapter 5.4). This might become necessary due to long calculation time for large structures on multiple layers and many frequency points. For analyzing a new or changed structure press In a first step the reaction integrals have to be calculated for a new structure. This creates a file *.rea (see chapter 5.2). In a second step the structure will be analyzed by an iterative solution process. This creates finally the solution file *.slv (see chapter 5.3) which contains all relevant dates as current distribution, input impedance and radiation pattern which can be viewed (see chapter 4.3). The file *.snp contains the scattering parameter in a touchstone format. The file *.pat contains the three dimensional radiation pattern. 

      
      +-------------+                                    
      |             |                   +---------------+
      |  Program    | ----------------  |   Inputfile   |
      |  Mstrip40   | ----edit--------  |     *.str     |
      |             |                   +---------------+
      |             |                                    
      |             |                                    
      |             |                   +---------------+
      |  Ms_calc    | -----+---------   | Reactioninteg.|
      |             |      |            |     *.rea     |
      |             |      |            +---------------+
      |             |      |                             
      |             |      |            +---------------+
      |  Ms_patte   |      +----------  | Solutionfiles |
      |  Ms_curre   | ----------------  | slv currents  |
      |  Ms_smith   |                   | snp s-paramet.|
      |             |                   |     real,ima. |
      +-------------+                   | sn1 mag.,phase|
                                        | pat pattern   |
                                        +---------------+

5.1 Main menu and the Format of the input files *.str

All input data are given by ASCII files with the extension *.str. For modifying this file an ordinary ascii editor is needed. The file may be edited in advance or within the program. In this case the favorite editor may specified in the file mstrip40.ini. The most important datas may be set within the main program mstrip40. The structure file will automatically updated by the program in this case.

5.1.1 Defining general parameters

The general parameters like frequency, layers and segment size are defined in the head of the structure file. The following shows the head of the example file demo1.str: 
+---------+---------+---------+---------+---------+---------+---------+
!                                                                     !
!    DEMO1    Microstrip antenna with an edge coupled feed, for       !
!             comparison with measurement see reference [2] or        !
!             [3, p. 77].                                             !
!                                                                     !
+---------+---------+---------+---------+---------+---------+---------+
!         !  START  !  STOP   ! INCREM. ! POINTS  ! (FREQUENCY IN GHZ)!
! FREQU.  ! 2.120000! 2.120000! 0.000000! 1.000000!---------+---------!
+---------+---------+---------+---------+---------+---------+---------+
!         !   NR.   ! DIELEC. ! LOSSES  ! HEIGHT  !  RE(ZS) ! IM(ZS)  !
!         !         !         ! (10E-3) ! (IN MM) !  (IN OHM * 10E-3) !
! LAYER   ! 1.000000! 2.200000!-2.000000! 1.570000! 0.000000! 0.000000!
! LAYER   ! 2.000000! 1.000000!-1.000000! 0.000000! 0.000000! 0.000000!
! LAYER   ! 3.000000! 1.000000!-1.000000! 0.000000! 0.000000! 0.000000!
! LAYER   ! 4.000000! 1.000000!-1.000000! 0.000000! 0.000000! 0.000000!
! LAYER   ! 5.000000! 1.000000!-1.000000! 0.000000! 0.000000! 0.000000!
+---------+---------+---------+---------+---------+---------+---------+
!         !   NR.   ! Sx(MM)  !  Sy(MM) !  NO USE ! NO USE  ! NO USE  !
! SEGMENT !   1.    ! 3.333300! 4.700000!---------+---------+---------+
   .
   .
The program reads any line as comment except for the case it recognizes one of the following keywords:
FREQU
ZNORM (see also chapter 5.1.7)
LAYER
SEGMENT
STRUKTU (see chapter 5.1.2)
EXCITE (see chapter 5.1.7)
SLOT (see chapter 5.1.6)
NOGROUND (see chapter 5.1.8)
ITERAT (see chapter 5.3)
PRECIS (see chapter 5.5)
LUDWIG (see chapter 4.3.2)
CIRCUL (see chapter 4.3.2)
If the line starts with one of the keywords above the following six numbers are read as real variables by the program (do not forget the decimal point!!!).
FREQU: reads the frequency range in GHZ. The number of points are defined either by the increment or directly. The direct definition of the points overrides the increment.
ZNORM: specifies the reference impedance in ohm. Without the string ZNORM=50 ohm are used at all ports. The impedance can be different for multiple port analysis (see chapter 5.1.7)
LAYER: Defines the used dielectric layers. Up to four layers are permitted (The demo version has only one). The dielectric constant has to be given in real and imaginary part e=e'-j*e''. In case of using tan(delta) of a material calculate e'-j*e'' = e'(1-j*tan(delta)). The height of the dielectric layer is given in mm. A thickness of zero is permitted for all except one layer. Also the surface impedance of the metalization is defined in terms of real and imaginary part. For copper loss use: Zs=sqrt(j*Z0*k0/S), Z0=377Ohm, k0=2*pi/Lambda, S app. 10**7, see reference [3,12].
SEGMENT: Defines the segmentation size for the structure. Therefore it also defines the number of basis functions (unknowns in the linear system) which are used to approximate the current on the structure. The size is given in mm in x and y direction. The ratio of SX/SY should not be too large or too small. Only one segmentation size has to be specified. The second segment size (half the size of the first one) is defined automatically.
Numbers in boxes marked with 'not in use' are currently of no significance.

5.1.2 Defining the geometry of the structure

The geometry of the structures is defined by the keyword STRUKTU. The first parameter (number of the structure) defines the segmentation size which is used and on which layer the structure is located.
Nr. 1 ------> large Segment Nr.1 Sx x Sy on layer one
Nr. 2...6 --> see chapter 5.1.4/5 for different segment sizes and multilayer structures
Example from demo1.str for a single structure and one layer:
+---------+---------+---------+---------+---------+---------+---------+
!         ! NUMBER  ! NOT IN .! NOT IN  ! NOT IN  ! NOT IN  ! NOT IN  ! 
!         ! OF STRU.! USE    .! USE     ! USE     ! USE     ! USE     !
! STRUKTU !    1.   !   0.    !    0.0  !  0.0    !    0.   !   0.    !
+---------+---------+---------+---------+---------+---------+---------+
...................................................                     
...................................................
...................................................
....................................#########......
....................................#########......
....................................#########......
....................................#########......
....................................#########......
....................................#########......
........1####################################......
....................................#########......
....................................#########......
....................................#########......
...................................................
...................................................
...................................................
+---------+---------+---------+---------+---------+---------+---------+
The actual shape of the structures is then specified by the symbols:
".", "#" and "1...9"

"." is the graphical boarder (arbitrary but large enough)
"#" specifies the position of a segment of size Sx x Sy. The area specified by the segments is filled by the program with x and y directed rooftop basisfunctions (see reference).
The combination: 
...................................................
...................................................
........##..........fills in an x-directed basisfunction.......
...................................................
.........#..........fills in an y-directed basisfunction.......
.........#.........................................
...................................................
+---------+---------+---------+---------+---------+---------+---------+
Alternatively the symbols "X" or "%" are accepted for "#".
The size of the larger segment should be approximately:
Sx app. Sy. app. 1/5 .. 1/20 of the wavelength in dielectric

5.1.3 Excitement of the structure

"1" (or "2"..."9", see chapter multiple ports 5.1.7) specifies the position of the excited basisfunction connected to the port no. 1...9, respectively. For one port only use Nr. 1. The direction of the connection to the structure is arbitrary and is allowed in any layer at any structure: 
           1#########     or   #####3        
                
                
      or   1   or     #   or   1#####   or  33
           #          #        1#####       ##
           #          #                     ##
           #          7                     ##
                                            ##
Ports with the same number are connected parallel. The number 1..9 represent also a segment which is important to identify the reference plane,

Series excitement in a line is established in the following way 

        ######11###########
Remarks: in this case no automatic correction of input- impedance can be provided! The series excitement is allowed only in x-direction!
Warning: the program adds automatically an auxiliary stub consisting of app. 2..10 (depending on the wavelength) segments at the open end. This auxiliary stub is optimized for the center of frequency range.
Avoid too large frequency ranges!
Avoid structures in the close vicinity of the ports!

5.1.4 Different segment sizes

In case of using different sizes of segments at least two structures have to be specified. Structure Nr. 1 specifies the structure using large segments and structure Nr. 2 the small segments, respectively. 
                      .
+---------+---------+---------+---------+---------+---------+---------+
!         ! NUMBER  ! NOT IN .! NOT IN  ! NOT IN  ! NOT IN  ! NOT IN  ! 
!         ! OF STRU.! USE    .! USE     ! USE     ! USE     ! USE     !
! STRUKTU !    1.   !   0.    !    0.0  !  0.0    !    0.   !   0.    !
+---------+---------+---------+---------+---------+---------+---------+
...................................................                     
...................................................
                      .
                      .
+---------+---------+---------+---------+---------+---------+---------+
!         ! NUMBER  ! NOT IN .! NOT IN  ! NOT IN  ! Shift   ! Shift   ! 
!         ! OF STRU.! USE    .! USE     ! USE     ! IN X    ! IN Y    !
! STRUKTU !    2.   !   0.    !    0.0  !  0.0    !   10.   !   5.    !
+---------+---------+---------+---------+---------+---------+---------+
...................................................                     
...................................................
                      .
                      .
+---------+---------+---------+---------+---------+---------+---------+
Nr. 1 ----> large Segment Nr.1 Sx x Sy on layer one

Nr. 2 ----> small Segment Nr.2 Sx/2 x Sy/2 on layer one
Nr. 3...6 -> see chapter 5.1.5 for multilayer structures
For the structures Nr. 2 and higher a shift in x- and y-direction relative to the first structure can be specified.
To guarantee the continuity of the current an appropriate overlap of both basisfunctions has to be provided.

5.1.5 Multiple layers

Structures consisting of large and small segments are allowed in three different layers. The sizes of the segments and the used layer are defined in the following way by the structure number:
Nr. 1 ----> large Segment Nr.1 Sx x Sy on layer one

Nr. 2 ----> small Segment Nr.2 Sx/2 x Sy/2 on layer one
Nr. 3 ----> large Segment Nr.1 Sx x Sy on layer two
Nr. 4 ----> small Segment Nr.2 Sx/2 x Sy/2 on layer two
Nr. 5 ----> large Segment Nr.1 Sx x Sy on layer three
Nr. 6 ----> small Segment Nr.2 Sx/2 x Sy/2 on layer three
The fourth layer and fifth layer (dielectric cover) is on the top of the fifth and sixth structure. With this option electrodynamically coupled structures and antennas are analyzed (see demo6 ff.). By viewing the current the keys "1,2; 3,4 and 5,6" control the display of the corresponding structure.

5.1.6 Slot coupling

The keyword SLOT causes the program to switch over to slot coupling. A metallic sheet is placed between the layer 2 and 3. The structures 3 and 4 are now interpreted as magnetic current and therefore slots are modelled now in the metallic sheet (groundplane between layer 2 and 3). By viewing the current the structures 3, 4 represent the electrical field in the slots rather than the electrical current.

5.1.7 Multiple ports

The program is mainly written to analyze single port microstrip antennas but allows also calculations of multiple port structures. However, for time saving purpose the multiport capability is limited in a way that not the complete scattering matrix is calculated with a single run of the program.
The reference impedance for the different ports can be chosen individually: 
c---------+---------+---------+---------+---------+---------+---------+
c         !  PORT 1 !  PORT 2 !  PORT 3 !  PORT 4 ! PORT 5-7! PORT 8-9!
c ZNORM   !   50.   !   50.   !   70.   !   70.   !  100.   !  120.   !
c---------+---------+---------+---------+---------+---------+---------+
There a two options to use the multiport capability of the program:

1) Calculation of the scattering matrix of an n-port, example T-junction: 

...................................................
...................................................
......1###################################2........
......................#............................
......................#............................
......................####################3........
...................................................
...................................................
...................................................
Only port 1 is then excited. The other 8 Ports (2-9) are loaded with the reference impedance given in the structure file (ZNORM). Only the scattering parameter s11, s21, s31 ... s91 are then calculated and displayed in the smith diagram. In order to obtain the complete scattering matrix of an N-Port N analyzing steps with rearranged excited ports are necessary (see example file demo12).

2) Calculation of active input impedances of an n-port excited at all ports (needed for array calculation) 

c---------+---------+---------+---------+---------+---------+---------+
c         !  PORT 1 !  PORT 2 !  PORT 3 !  PORT 4 ! PORT 5-7! PORT 8-9!
c ZNORM   !   50.   !   50.   !         !         !         !         !
c EXCITE  !    1.   !   1.    !   1.    !   1.    !   1.    !   1.    !
c---------+---------+---------+---------+---------+---------+---------+
Port 1 to 9 are excited with the voltage specified in the input file with EXCITE. The voltage sources are matched internally with the reference impedance (ZNORM). Therefore contributions from the sources connected at the other ports are absorbed in the generator as in reality. The program calculates then the active input impedances or reflection coefficients rho1...9 at the corresponding ports and displays them in the smith chart (see example file demo14).

5.1.8 No ground option

The ground plane below layer 1 is removed by adding the keyword NOGROUND (see demo15, 16). With this option you can calculate structures in free space or antennas on finite ground plane. However, this is only an approximation to truncated microstrip antennas, due to the fact that the extent of the dielectric slab is still assumed to be infinite. Caution, with this option the automatic correction of the stub can not carried out.

5.2 Calculating the reaction integrals

Pressing causes the program to calculate first the reaction integrals for the used dielectric layers and segment size. The calculation is repeated by the program for any frequency point and all layer combinations. The integrals are precalculated and stored into the file *.rea before actually analyzing the structure (see chapter 5.3). Each set of reaction integrals needs approximately 40 seconds on PC486/33MHz (precision factor=1).
When the dielectric layer, the frequency or the segment size is changed the reaction integrals have to be recalculated. If only the shape of the structure is changed by rearranging the segments no new reaction integrals have to be calculated!

5.3 Iterative analyzing of the structure

If the geometry is specified and the reaction integrals are calculated the problem is analyzed in a second step. An iterative solution procedure is called to solve the linear system build up by the reaction integrals and the geometry of the structure.
The iterative solution is terminated when the error drops below one percent or the step exceeds the number of used basis functions (unknowns). There are two iterative solvers to choose. The normal iterative conjugate gradient procedure (cg) and an improved version (cra) (see reference [5] for details). The program uses the cra-algorithm unless otherwise specified by the user: 
+---------+---------+---------+---------+
!         !  error  !cg1  cra2! itmax   !
! ITERAT  !  0.01   !   1.0   ! 1000.   !
+---------+---------+---------+---------+
With the keyword ITERAT the user can determine the error where the iteration is truncated, the method (1=cg, 2=cra) and the maximum number of used iterative steps.
The computer time needed for the solution depends strongly on the number of used basis functions (segments). The time reaches from 25 seconds (200bf) to 25 minutes (1000bf) to hours for more basis functions on a PC486/33. The maximum number of unknowns (basisfunctions) is set to 8000 but can be enlarged to the limit of available memory.

If only the shape of the structure is modified by rearranging the segments no new reaction integrals are calculated.

5.4 Batch calls

For large structures using many segments and several frequency points it is convenient to use a batch call, therefore calling the program several times with different structures by a *.BAT file. Press the button and you are ask to edit or to start a batch job. Example for a *.bat file: 
drive:\pathname\filename1 
drive:\pathname\filename2 
drive:\pathname\filename3
   . 
   .
Just add all structure file names (without extension) to the batch file.

5.5 Controlling precision of computation

The precision of the computation might controlled by the user by using the control word PRECIS: 
+---------+---------+---------+
!         ! factor  ! radius  !
! PRECIS  !   1.    !  20.0   !
+---------+---------+---------+
The precision factor is initially set to one which causes adequate numerical precision calculation sufficient for most of the cases (all Demo files are calculated with factor=1). However, for very small, very large basis functions or thick high permitive layers more precise numerical calculation might become necessary. The precision factor ranges from 1 up to 5. A high precision factor increases the computation time mainly for the calculation of the reaction integrals (see chapter 5.2).

The precision radius allows the user to control the coupling radius of the basis functions. The radius is set initially to 20 small and 10 large basis functions, respectively. This means that the influence of to basis function with a larger distance than 10 (20) times the segment sizes is neglected. If approximately two third of the structure is captured by this radius the results are usually sufficient.

However, sometimes (for example for mutual coupling) a larger coupling radius are necessary. A high coupling radius increases the computation time manly for iterative solution (see chapter 5.3). The maximum radius is currently 60 small segments (sx/2,sy/2) and 30 large segments (sx,sy).

6. CHANGES SINCE LAST VERSION

CHANGES SINCE VERSION 1.0
- Radiation pattern plot is added

- wrongly displayed shifted location of excitation is corrected
CHANGES SINCE VERSION 1.1
- Integration routines for reaction integrals are improved in accuracy

- Multilayer capability is added (up to four layers)
- Description symbols of geometry are changed 1--# (see text above)
- description of geometry is simplified by defining the segment size (#) rather than using basis function
- Structurfilename may be passed by the command line: mstrip
- In case of new file mstrip.str is loaded to newfilename.str
CHANGES SINCE VERSION 2.0
- Batch call possible: mstrip filename,r,a,q

- limited multiport option added (9 ports)
- description of ports in structurfile is simplified
- Slot option added
CHANGES SINCE VERSION 2.1
- finite ground option added

- creation of *.pat file added (radiation pattern)
- series excitement in line added
- background color may be changed
CHANGES SINCE VERSION 2.2
- surface impedance added
CHANGES SINCE VERSION 2.3
- coupling radius extended

- precision of computation is controlled by user
- efficiency calculation added (radiation pattern)
- input string used for structure-reading is extended to 300
- ludwig3 definition for pattern added
CHANGES SINCE VERSION 2.4
- wrong 5 Degree shift in radiation pattern corrected (SLOT)

- space domain integration improved in accuracy
CHANGES SINCE VERSION 2.5
- restriction with slot and noground option removed
CHANGES SINCE VERSION 2.6
- shift to Mstrip40 Windows version

- five layers
CHANGES SINCE VERSION 1.1 (Windowsversion)
- Module Ms_patte: correct update of drawing
- Module Ms_calc: wrong transmission parameters in case of mixed basis functions corrected

7. COMMENTS

This program is still in experimental status. Error reports and any comments would be gratefully appreciated by the author. Technical support and improved demo versions of the program will be provided in return as work progresses.

This program is provided AS IS without any warranty, expressed or implied, including but not limited to fitness for a particular use.

8. REFERENCES

[1] G. Splitt, "Rectangular electromagnetically coupled microstrip antennas in multilayered structures," 18th European Microwave Conference, Stockholm, Sweden, p.1043-1048, Sept. 1988
[2] G. Splitt, "A rapid method for arbitrary microstrip-structures using the FFT-algorithm," 20th European Microwave Conference, Budapest, Hungary, Sept. 1990, p. 1481-1486
[3] G. Splitt, "Effiziente Rechenverfahren zur Analyse von komplexen Einzel- und Gruppenantennen in Streifenleitungstechnik," Phd-Thesis, University at Wuppertal, 1991, or DLR Forschungsbericht DLR-FB 90-53 and translated in English: "Efficient numerical Techniques for the Analysis of complex Microstrip-Antennas and Arrays," ESA-TT-1259, 1993
[4] G. Splitt, "Improved numerical strategies for rigorous analysis of microstrip antennas," 23th European Microwave Conference, Madrid, Spain, Sept. 1993, p.354-356
[5] W. Wertgen, "Elektrodynamische Analyse geometrisch komplexer (M)MIC-Strukturen mit effizienten numerischen Strategien," Phd-Thesis, University GH Duisburg, 1989
[6] J. Heinstadt, "New approximation technique for current distribution in microstrip array antennas," Electronic Letters, Oct. 1993, pp. 1809-1910
[7] M. Kahrizi, et. al., "Analysis of a Wide Radiating Slot in the Ground Plane of a Microstrip Line," IEEE Trans. on Microwave Theory and Techniques, Jan. 93, p. 29-36
[8] L. Barlatey, et. al., Printed radiating Structures and Transitions in Multilayered Substrates, International Journal of Microwave and Millimeter-Wave Computer-Aided Engineering, Vol. 2, No. 4, 1992, p. 273-285
[9] Sullivan, P.L.; Schaubert, D.H., "Analysis of an aperture coupled microstrip antenna," IEEE Trans. Antennas Propagat., Aug. 1986, p. 977-984
[10] Pozar, D.M.; Voda, S.M., "A rigorous analysis of a microstrip fed patch antenna," IEEE Trans. Antennas Propagat., Dez. 1987, S. 1343-1150
[11] Radmanesh, M.M.; Arnold, B.W., "Generalized Microstrip-Slotline Transitions: Theory and Simulation vs. Experiment, Electronics Letters, Jun. 1993, S. 88-95
[12] Mosig, J.R.; Gardiol, F.E., "Ohmic losses, dielectric losses and surface waves effects in microstrip antennas," URSI Int. Symp. on Electromagnetic Theory, Spain, 1983, S. 425-428
[13] Ludwig, C.L.; "The Definition of Cross Polarization" IEEE Trans. Antennas Propagat., Jan. 1973, S. 116-119

9. LIST OF EXAMPLES (DEMO FILES)

DEMO1 Microstrip antenna with an edge coupled feed, for comparison with measurement see reference [2] or [3, p. 77]. 
DEMO2 Microstrip antenna with an inserted feed, for comparison with measurement see reference [2] or [3, p. 78]. 
DEMO3 the same as DEMO2 but using smaller segments. 
DEMO4 Microstrip antenna with an inserted feed and edge coupled, for comparison with measurement see reference [6]. 
DEMO5 the same as DEMO4 but using smaller segments. 
DEMO6 Microstrip antenna with an electrodynamically coupled feed, for comparison with measurement see reference [1] or [3, p. 79, case a]. 
DEMO7 Microstrip antenna with an electrodynamically coupled feed, for comparison with measurement see reference [3, p. 79, case c]. 
DEMO8 Double stacked microstrip antenna with an electrodynamically coupled feed, for comparison with measurement see reference [3, p. 82]. 
DEMO9 Radiating large slot coupled by a microstrip line, for comparison with measurement see reference [7]. 
DEMO10 Radiating large slot coupled by a microstrip line, for comparison with measurement see reference [8, figure 6]. 
DEMO11 Slot coupled microstrip antenna, for comparison with measurement see reference [9, figure 4]. 
DEMO12 Hybridring, example for a multiple port scattering parameter calculation. 
DEMO13 Electrodynamically coupled disturbed antenna for producing circular polarization, with dielectric cover. 
DEMO14 Small array calculation, active input impedance 
DEMO15 Dipol in free space (reference) 
DEMO16 Patch on finite ground plane 
More Demos (structure files only, not precalculated): 
DEMO17 Crossed slot coupled patch for dual polarization 
DEMO18 Edge coupled patch with matching feed network 
DEMO19 Microstrip-slot-microstrip transition,for comparison with measurement see reference [11, figure 8] 
DEMO20 Microstrip antenna with two electrodynamically coupled feedlines to produce circular poarisation 
DEMO21 Small Dipol in leaky wave structure to produce high gain [3, figure 11] 

10. UPDATES, MORE INFO

The updates, an increasing number of more demo files and some more info will be maintained on the server: http://intek.e-technik.fh-kiel.de/Splitt.htm

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