_getstarted.txt

zip contains tool for Antenna Modelling with examples

	geometry wire with high RF-voltage/current.

	To get rid of these 'unusable' high values, please use 'Near-field -> Ignore high 
	values" or push the <Del> key. You are asked for maximum field-strength. Please
	enter a value of 250 (V/m). The display should now change to a more colorful
	view. The color-bar on the left is also updated.
	Another way to change the color-resolution, is to use the <Alt> together with the
	<Page-up> or <Page-down> keys. This will change the linear scale to a more logarith-
	mic scale. Use 'Show -> Geometry' or the "G" key to display the geometry- structure.
	
	Initially the field-strength on the XY plane for a certain Z value is displayed.
	To change the Z-value use the cursor-left or -right key's. To change between
	XY, YZ and XZ plane, use the spacebar.
	
	On the Geometry form you are also able to display the Near-field points. Use
	'Show -> Near/far field" or push the "R" key. Use the spacebar to switch between
	3D view, or 2D XY, YZ or XZ view. Use <Shift> plus the arrow-keys to change the
	2D plane coordinates. Use <Page-up>/<Page-down> to change the dot-size.

	On the 'Pattern' form on the left and on the right of the 2D plane, two black
	indicator lines are displayed. These indicators are used to select a certain Y- or
	Z value for displaying the field-strength using a line-chart. Use the Up/Down arrow
	keys to change position, use <Page-Up>/<Page-down> to switch between 2D and line-
	chart viewing.

	Use the 3D-viewer/<F9> (4nec2X only) or the "Plot -> 3D" menu-bar command (if 
	gnuplot is availle) to view the far-field data in 3D perspective.


8) Generate and use ItsHF area-coverage propagation data.

	This feature works in co-operation with the NTIA/ITS HF propagation software using
	the VOACAP, ICEPAC or REC533 model. This software is freely available on the internet.

	After installing this software, you should check the ItsHF 'main' folder setting 
	under 'Settings -> Folders -> ItsHF folder' on the Main (F2) window. Also check if
	all 6 options under 'Settings->ItsHF settings->Area Coverage/Point-to-Point' are 
	checked and if VOACAP is selected as the model to use.

	With this first try, we use the 3el-inverted-V.nec as our input file. First we run a
	standard 3D far field calculation, to determine the Phi angle for the main lobe. For
	this antenna this is 90 degrees (positive theta).

	After pushing the <F7> key again, we now select the 'ItsHF 360 degree gain table'
	option. If not already set, specify 90 degrees for the main beam angle (Phi-max) and
	select 'Map' as the plot-type you would like to see. Also check if the 'Span' selec-
	tion-box is set to 'Single-step'. Then click <Generate>.
	After running the nec2d(xs) engine and creating an ItsHF antenna-file, the ItsHF engine
	is automatically started (characterized by the counting number sequence). 

	When done, a color-full map is displayed, indicating propagation performance over 
	Europe for the antenna under test and for the specified parameter ('Param' control),
	or other region as specified by the 'Xmtr location' and 'Map' controls). In the ItsHF
	plot-window you can manually move and click the mouse to get specific distance and 
	param-values. Use the 'Parameter'menu-option to create a map for one of the other para-
	meters.

	The plot settings to create the map are saved in the '3el-inve.voa' file (truncated to
	eight char's) located in the '..ItsHFbc\areadata\4nec2' folder. You may start the ItsHF
	Area coverage program ('Run -> ItsHF area-coverage' on Main (F2) window) to open, view
	or modify this file and/or to run and create other user-specific Area-Coverage plots.

	In the '3el-inve.voa' file you will see that for the TX-antenna, '3el-inve.n13' is 
	set, indicating our NEC based antenna. This type-13 antenna-file is located in the 
	'..\ItsHFbc\antenna\4nec2' sub-folder. You may use 'Run -> ItsHF antenna view' to 
	check the pattern using the ItsHF antenna viewer 'HFant'.

	Each time a 'Area-Coverage' calculation is done by 4nec2, a new *.voa input file is
	created. This file is based on the information included in a default/template ItsHF
	input-file called 4NEC2.VOA placed in the ..\ItsHFbc\antenna\default folder.
	Most of the important ItsHF settings are available through the controls on the 
	'Generate (F7)' window. when <def> or <default> is selected, to settings as specified
	in the template-file are used. You may modify this template file for specific needs.

	When using the '360 degree Gain-table' option, a type-13 antenna file (*.n13) is pro-
	duced containing a 360*90 degree gain-table for a single frequency. This type of an-
	tenna-file is especially suited for Area-Coverage plots.

	When a Point-to-Point Graph type of plot is needed, one could better use the 'Gain @
	30 frequencies' option. This will produce  a 90 degree gain-table for the specified
	antenna direction (bearing) for all integer frequencies from 2 to 30 Mhz. The required
	direction is specified using the 'Xmtr' and 'Rcvr' location buttons.

	For Time- and Distance (point-to-point) plots you may use both '360 degree gain-table'
	(type 13) or 'Gain @30 freqencies' (type-14) antennas. When a type-13 antenna is used,
	howevert you are able to more precisely specify the working/design frequency for the
	antenna under test. 

	SWEEP area-coverage:

	With the 'Sweeper' function it is possible to let 4nec2 automatically generate a 
	specified range of area-plots for you. For instance, representing the area-coverage
	change when increasing the antenna height from 15 to 30 meters.

	To do this, again select the 3el-inverted-V.nec file as our antenna of interest and
	push <F12> to start the optimizer/sweeper. Select 'Sweeper' using the 'Function' 
	box and select 'Area-coverage' using the 'Option' box. Select 'hgh' as the variable
	to sweep and specify min=15 and max=30 (meters). Set 90 degrees as the Phi angle for
	the main-beam and specify 10 steps of 10% variable change, and click <Start>.

	During all the calculations, which will take some time, you will see the windows
	popping on and off the screen. During all these window flashing the ItsHF area-plots
	are automatically cut and pasted into the 4nec2 software. After some time a message-
	box shows up showing 'Sweep ready'.

	Clicking <OK> will show-up the so called 'picture-viewer' window in which all ItsHF
	plots have been copied. Using the scroll-bar, the left and right-arrow keys or the
	'1' to '9' number keys, you can scroll through or switch between all created plots.

	You are now able to evaluate the effect of changing antenna height on area-coverage.
	You will notice that for a height of around 21 meters the optimum F/B ratio is reached.
	This was the original height the antenna was optimized for.

	This 'picture-viewer' window is also used if, for a Map type of plot, the 'Span' se-
	lection box is set to a setting unequal '<def>' or 'single-step'. With these settings,
	multipe plots are generated which in turn are copied into the picture-viewer. When all
	calculations are done, you can use the scroll-bar to scroll through all the plots.

	Latest test-results on different systems show that this automatic cutting and pasting
	appears to be sensitive. If you should experience difficulties during this process,
	please contact me so I can deliver you an alternative.

9) Generate and use ItsHF point-to-point propagation data.

	Point-to-point propagation plots are automatically created if you select a 'Time',
	'Dist(ance)' or 'Graph' type of plot on the 'Generate (F7)' window. Its recommended
	to use the 'ItsHF Gain @30 frequencies' option when running (multi-frequency) point-
	to-point plots.
	When <Generate> is clicked, if required, the Nec engine is started and (new) ItsHF
	antenna and point-to-point files are created. Next, the ItsHF engine is automatically
	started to create the requested plot. 
	When the plot is visible you can use your mouse-pointer to click on the plot and see
	specific time/distance/frequency values. For Time- and Distance plots use the 'New 
	plot' menu-bar function to select an alternate time, frequency and/or parameter. 
	The number of time values to select between is determined by the 'Span' selection on
	the 'Generate (F7)' window.
	When running a 'Graph' type of plot, you must manually select the parameter to plot
	just before the plot is visualized on the screen.  Use the 'Parameters' menu-bar op-
	tion on the plot-window to select another parameter to plot.
 
	
	To be continued.....

	(it is suggested to periodically check the 'unofficial Nec-page' for new versions)


p.s.	I apologize for my English which is far from perfect, but nevertheless I hope this 
	document, including all the syntactical- and other errors, does deliver some usefull
	information.


Appendix A: 

	Example: Creating a T-antenna on a box using the Gometry editor

	The second example will give a brief description about one of many possibilities how 
	to create a much more complex 3D-model consisting of a T-antenne on a grid-type box.

	The below might seem as a lot of work, but once you 'get the point' you will see
	the rather straightforward use of available possibilities.

	a) 	Create a new design using'New' in the Geometry-editor 'File' menu.
	b) 	Change default frequency of 299.8 to 299.9 Mhz, indicating frequency is set.
	c) 	Select 'Rect-grid' from the 'Create' menu and specify a (highlighted) 'Y'-
		coordinate of 0.2 to create the back-side of the box (Y-axis pointing backwards)
	d)	Draw a rectangle from X=-0.2 and Z=+0.2 to X=+0.2 and Z=-0.2 meters, using 4 
		sections per side.

	e) 	One by one select left- and right outmost-wires and delete them, to avoid over-
		layed wires when attaching grids representing left- and right-side of the box.
	f) 	Select all left-over grid-lines again using the 'selection-box' method.

	g) 	Switch to XY-plane (view from above) and use <Ctrl>+C and <Ctrl>+V to copy and 
		paste selected wires to create a second (front) side of the box. 
	h) 	Move the new red-line, representing the new pasted 'grid' to an Y coordinate 
		of -0.2 meters and an X coordinate from -0.2 to +0.2 meters.
	i)	Switch to 3D-view, inspect structure and use 'File->Save as' to back-up the 
		new structure as for instance 'try1.nec'.

	j) 	Switch to YZ-plane, select 'Rect-grid ' in the 'Create' menu and set a (high-
		lighted) X-coordinate of 0.2 meters to create the right side of the box.
	k) 	Now draw a rectangle from Y=-0.2 and Z=0.2 to Y=+0.2 and Z=-0.2 meters, using 4 
		sections per side.
	l)	Switch to XY-plane (view from above) and use copy/paste to create the left side
		of the box and move the new 'grid' to an X-coordinate of -0.2 meters.
	m)	Switch to 3D view, inspect structure, if okay, backup using 'File->Save'

	n)	In 3D view, unselect by clicking anywhere near the structure while holding down
		the <Shift> key.
	o)	One by one select and delete all upper and lower wires to avoid overlayed wires 
		when adding the top- and bottom-sides of the box.
	
	p)	Switch to XY-plane, Use 'Create->Rect-grid' and set an Z-coordinate of 0.2 meter
		to create the upper side of the box and draw the required rectangle.
	q)	Switch to 3D-plane, use copy/paste to create the bottom side of the box and
		move the grid to the correct position.
	r)	Our box is now ready, backup it using 'File->Save'.
	
	s)	Set XZ plane and use Right mouse-button to shift structure down to lower half
		of the window.
	t)	Switch to 'Add-mode' and draw a wire from X=0 and Z=0.5 to X=0 and Z=0.2
	u)	Switch back to default 'Select-mode', select 3D-plane and locate mouse-pointer 
		on connection between wire and box.
	v)	Click right mouse-button for 'Edit' pop-up menu and use 'Disconnect end' and move
		end-2 to center of the upper-side of the box.	
	
	w)	Switch to 'Add-mode' and select XZ-plane to create two wires from X=-0.2 to X=0 
		and from X=0 to X=+0.2, both for a Z value of 0.5 meter. 
	x)	Select the 'Source' button and add a voltage source just above the connection
		for the vertical wire to the center of the box.
	y)	Our T-antenna on a box is now ready, save it or use <F7> to generate a far-field
		pattern. 
	
	As a check, compare your model with the T-box.nec file.