An antenna model is a representation of a real-world antenna in a computer program. This kind of model should not be confused with a scale model that sometimes is built to measure the radiation characteristics of an identical antenna with a larger physical size...
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AN-SOF is a comprehensive software tool for the modeling and simulation of antenna systems and radiating structures in general. AN-SOF is intended for solving problems in the following areas...
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When AN-SOF is started, the initial screen contains the following components: The title bar contains the name of the currently active project (.emm file)...
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Preferences include the unit system to be used for showing input and output data, the workspace appearance, and several miscellaneous options. Preferences can be accessed via...
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The background of the workspace can be white or black. When a white (black) background is chosen, all wires will default to black (white) unless a different color is specified for certain wires. The workspace color can be set by going to...
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Pressing ALT with the underlined letter of a menu item will execute the command associated with the item. The following keys and associated actions are available...
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When a project is saved in AN-SOF, multiple files that have the same name as the project are saved. Each file has a unique extension that...
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In the traditional Method of Moments (MoM) the structures to be modeled are divided into straight wire segments. Straight segments fit well the shape of linear antennas like dipoles and arrays constructed using dipoles. However, there are many antennas...
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The simulation parameters can be set in the Setup tabsheet. This page has the following panels: Frequency, Environment, Far-Field, Near-Field, Excitation, and Settings...
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The Frequency panel has three options: Single, List and Sweep. By choosing one of these options the simulation can either be performed for a single frequency, for frequencies taken from a list or for a frequency sweep...
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Go to the Setup tab in the main window and select the Environment panel. The relative permittivity and permeability of the surrounding medium can be set in the Medium box, Fig. 1. Four options are available for the ground plane...
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The far field can be computed after having calculated the current distribution previously. Thus, the parameters set in the Far-Field panel have no effect in the determination of the currents and can be modified at any time. However, the far field must be...
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The near field can be computed after having calculated the current distribution previously. Thus, the parameters set in the Near-Field panel have no effect in the determination of the currents and can be set at any time. However, the near field must be recalculated every...
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Go to the Setup tab in the main window and select the Excitation panel. There are two types of excitations: Discrete Sources and Incident Field...
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Go to the Setup tab in the main window and select the Settings panel, Fig. 1. The accuracy of the integrals involved in the calculations can be set in the Settings panel. The Quadrature Tolerance is the error in the evaluation of...
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Go to View > Project Details in the main menu to display the Project Details window, where a summary of the project information is shown...
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AN-SOF has different types of wires. Each wire type has its own geometrical parameters, attributes and materials that can be set in a specific Draw dialog box. This dialog box allows us...
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The Attributes page belongs to the Draw dialog box of the chosen wire type, Fig. 1. In the Attributes page the following attributes can be specified...
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The Materials page belongs to the Draw dialog box of the chosen wire type, Fig. 1. In the Materials page the following attributes can be specified...
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If wires with non-zero resistivity have been drawn previously and the whole structure must now be considered as a perfect electric conductor, all resistivities can be disabled...
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If wires with a coating shield or insulation have been drawn previously and the whole structure must now be considered as composed of bare conductive wires, all coatings can be disabled...
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The wire cross-section can be chosen from a combo-box in the Attributes page of the Draw dialog box for the chosen wire type...
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Linear wires can be exported from AN-SOF to a text file in NEC format (extension .nec) by going to File > Export Wires in the main menu. Linear wires will be stored as GW lines. FR (frequency), EX (excitation), LD (load impedances and wire conductivity), RP (radiation pattern)...
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The Line refers to a linear or straight wire. Go to Draw > Line in the main menu to display the Draw dialog box for the Line...
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The Arc refers to a circular arc. Go to Draw > Arc in the main menu to display the Draw dialog box for the Arc...
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The Circle refers to a circular loop. Go to Draw > Circle in the main menu to display the Draw dialog box for the Circle...
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The Helix refers to a helical wire. Go to Draw > Helix in the main menu to display the Draw dialog box for the Helix...
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The Quadratic refers to a quadratic wire or parabola. Go to Draw > Quadratic in the main menu to display the Draw dialog box for the Quadratic...
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The Archimedean Spiral refers to the Archimedes’ spiral with polar equation r(a) = r0 + p/(2p) a, where r0 is the starting radius and p is the pitch. For a spiral with an integer number of turns...
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The Logarithmic Spiral refers to a spiral with polar equation r(a) = r0 exp(ba), where r0 is the starting radius (r at a = 0), b = p/(2pr0) and p is the starting pitch...
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A tapered wire is a wire with a variable radius along its length. The cross section of tapered wires is always circular. The radius is varied linearly along the wire and in defined steps, then a wire with a stepped radius is obtained...
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Wires in an external file can be imported into AN-SOF by going to File > Import Wires in the main menu. A sub-menu having four options will be displayed: AN-SOF, NEC, DXF, and MM formats. The DXF and MM formats must contain only...
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Lines or linear wires can be entered and edited in a table as follows: 1. Go to Draw > Tabular Input (Ctrl + T) in the main menu to show the table...
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Any wire in the workspace can be selected in three different ways: 1. By clicking on the Select Wire button (arrow icon) on the toolbar and then...
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Right-clicking on a wire brings up a menu. Choosing the Modify command from the pop-up menu shows the Modify dialog box, where the geometrical parameters and attributes of the selected wire can be modified...
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Right-clicking on a wire brings up a menu. Choosing the Delete command from the pop-up menu deletes the selected wire with all sources and loads placed on it...
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AN-SOF allows us to select a group of wires to edit them all at once. Click on the Selection Box button on the main toolbar. By left clicking on the workspace and dragging a box with the mouse, multiple wires can be selected...
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Click on the Selection Box button in the main toolbar. Then, left clicking on the workspace a box to select multiple wires can be expanded...
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Right clicking on a wire shows a pop-up menu. Choose the Wire Color command to display a dialog box that allows us to select a color for the wire...
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Right clicking on a wire will display a pop-up menu, where the Wire Properties command can be selected...
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A wire junction is automatically established whenever the coordinates of a wire end are identical to the end coordinates of a wire previously specified. However, two wires will be also connected automatically when their ends are spaced one tenth of the wire radius...
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After drawing the wire structure, we may need to modify the position or size of one wire or a group of them. To modify wires, we must first select them. Click on the Selection Box button on the toolbar and then expand a box using the mouse with the left button pressed...
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When drawing a wire structure, it is often necessary to copy wires from one position to another. An antenna array is an example where this situation occurs. To copy wires, we must first select them by first pressing the Selection Box button on the toolbar...
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Wire grids can be composed of curved or straight wires and can be used to model grids and approximate conductive surfaces. The wires of a grid do not overlap but are connected to each other...
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The Attributes page belongs to the Draw dialog box of the chosen wire grid type. As an example, Fig. 1 shows the Attributes page for the Plate...
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A wire grid can be modified by the procedure described in Modifying a Group of Wires...
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Click on the Selection Box button in the main toolbar. By left clicking on the workspace and dragging a box with the mouse, a wire grid can be selected...
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Click on the Selection Box button in the main toolbar. By left clicking on the workspace and dragging a box with the mouse, a wire grid can be selected...
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The Patch refers to a rectangular patch on the xy-plane composed of wires having a flat or rectangular cross-section. Use this wire grid to model patch and microstrip antennas...
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The Plate refers to a plate or bilinear surface. Go to Draw > Wire Grid > Plate in the main menu to display the Draw dialog box for the Plate...
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The Disc refers to a disc or circular surface. Go to Draw > Wire Grid > Disc in the main menu to display the Draw dialog box for the Disc...
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The Flat Ring refers to a disc with a hole at its center. Go to Draw > Wire Grid > Flat Ring in the main menu to display the Draw dialog box for the Flat Ring...
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Go to Draw > Wire Grid > Cone in the main menu to display the Draw dialog box for the Cone. There are three pages: Cone, Attributes and Materials.
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Go to Draw > Wire Grid > Truncated Cone in the main menu to display the Draw dialog box for the Truncated Cone. There are three pages: Truncated Cone, Attributes and Materials.
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Go to Draw > Wire Grid > Cylinder in the main menu to display the Draw dialog box for the Cylinder. There are three pages: Cylinder, Attributes and Materials.
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Go to Draw > Wire Grid > Sphere in the main menu to display the Draw dialog box for the Sphere. There are three pages: Sphere, Attributes and Materials.
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Go to Draw > Wire Grid > Paraboloid in the main menu to display the Draw dialog box for the Paraboloid. There are three pages: Paraboloid, Attributes and Materials.
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Discrete Sources, Incident Field, and Loads. A structure can be excited by discrete sources or an incident field. Refer to "Excitation by an Incident Field" for the second case. Discrete sources can be located on any wire segment...
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The Source/Load toolbar is used to place a source or load in a selected segment on a given wire. Sources and loads can also be edited with this toolbar...
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A source can be added to a selected wire segment by means of the following steps...
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A source can be edited by means of the following steps...
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A load can be added to a selected wire segment by means of the following steps...
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A load can be edited by means of the following steps...
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All the loads can be enabled or disabled at the same time. This option avoids deleting the load impedances when loads must not be considered in a simulation...
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To choose an incident plane wave as excitation of the structure, go to the Setup tab > Excitation panel and select the Incident Field option...
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The following incident field parameters can be set in the Excitation panel of the Setup tabsheet after clicking on the Incident Field option...
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The 3D-View interface allows us entering the parameters of the incident field in a graphical way. Follow these steps...
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A perfectly electric conducting (PEC) ground plane, parallel to the xy-plane, can be added to the model by means of the following procedure...
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A real ground plane, located on the xy-plane (Z = 0), can be added to the model by means of the following procedure...
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A dielectric substrate, located below the xy-plane (Z < 0), can be added to the model by means of the following procedure...
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A wire will automatically connect to the ground plane when the z coordinate of one of its ends coincides with the position of the ground plane...
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Once the frequencies, the environment, the geometry of the structure, the excitation, and the points of observation of the radiated field have been set, AN-SOF is ready to execute the calculations. First, the current distribution on...
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When the frequencies, the environment, the geometry, and the excitation are set, AN-SOF is ready to compute the currents...
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Once the current distribution on the structure has been obtained, the far-field in the angular ranges set in the Far-Field panel of the Setup tabsheet can be computed...
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Once the current distribution on the structure has been obtained, the near magnetic field at those points in space set in the Near-Field panel of the Setup tabsheet can be computed...
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When a calculation is executed using the commands under the Run menu, the Processing window will be displayed...
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There are simulations where we need to change the excitation of the structure frequently. For example, when we must often change the amplitudes of discrete sources or the direction of arrival of an incident field...
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AN-SOF can import a sequence of input files to obtain a corresponding sequence of output files, without user intervention in the middle of the process. The input files must be in NEC format...
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Commands to Display Results. The output data of a simulation can be listed in tables or displayed in graphs. All results are found under the Results menu...
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In the AN-SOF main window there is a Results tab, Fig. 1, where a table with the main results for a transmitting antenna is shown: input impedance, VSWR, directivity, gain and efficiency...
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Select the Plots tab in the AN-SOF main window to visualize the plots of the main results for a transmitting antenna as a function of frequency.
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Go to Results > Plot Current Distribution in the main menu to display a 3D graph of the current distribution on the structure. This command executes...
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Right clicking on a wire shows a pop-up menu. Click on the List Currents command to display the List Currents toolbar, Fig. 1. This toolbar allows us to select a wire segment to see the current flowing through that segment versus frequency...
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The following procedure allows us to select a wire segment to tabulate currents versus frequency...
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The following procedure allows us to select a segment that has a source to tabulate input impedance versus frequency...
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The input impedance as a function of frequency can be plotted in a Smith chart by clicking the Smith button in the Input List dialog box...
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Follow these steps to select a wire segment that has a load and to tabulate the load impedance versus frequency...
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Follow these steps to select a wire segment that has a source and to tabulate the source internal impedance versus frequency...
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The radiation pattern can be shown as a 2D rectangular plot by going to Results > Plot Far-Field Pattern > 2D Rectangular Plot in the main menu. This command displays the Radiation Pattern Cut dialog box...
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The far-field can be shown as a 3D plot by going to Results > Plot Far-Field Pattern > 3D Plot in the main menu. This command executes the AN-3D Pattern application...
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Far-field frequency spectra are obtained when a simulation is performed by specifying a list of frequencies or a frequency sweep. For each frequency, the far-field is calculated at the several directions given by the zenith (Theta) and azimuth (Phi) angular ranges and...
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Go to Results > Power Budget/RCS in the main menu to display the Power Budget dialog box, Fig. 1. The following list of parameters versus frequency will be shown...
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Go to Results > Power Budget/RCS in the main menu to display the Radar Cross Section dialog box, Fig. 1. The following list of parameters versus frequency will be shown when an incident field is used as the excitation...
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The far field patterns and spectra can be tabulated and exported by going to the following commands in the Results menu...
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Two commonly used metrics for quantifying the directional properties of an antenna radiation pattern are the front-to-rear ratio, F/R, and the front-to-back ratio, F/B.
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Go to Results > Plot Near E-Field Pattern > 3D Plot in the main menu to plot the near electric field as a 3D graph with a color scale. This command executes the AN-3D Pattern application...
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Near-field frequency spectra are obtained when a simulation is performed by specifying a list of frequencies or a frequency sweep. For each frequency, the near-field is calculated at those points specified in...
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