
	 














	                        YA YAGI ANALYZER




	             Copyright 1997 by Brian Beezley, K6STI
	                       All Rights Reserved




		YA Yagi Analyzer...............................1
		Using YA.......................................1
		F/B and F/R....................................3
		Frequency Menu.................................3
		Height Menu....................................3
		Elements Menu..................................4
		Taper Menu.....................................4
		Bracket Menu...................................5
		Boom Compensation..............................6
		Match Menu.....................................6
		Save Menu......................................8
		Algorithm Limitations..........................9
		Notepad.......................................10
		Graphs........................................10
		Patterns......................................10
		Options Menu..................................11
		Screen Colors.................................12
		Screen Print..................................12
		Index.........................................13

	---- YA YAGI ANALYZER ------------------------------------------

	        YA.EXE is a simple but accurate program for analyzing
	Yagi-Uda antenna designs on your PC.

	        YA analyzes Yagis hundreds of times faster than NEC- or
	MININEC-based antenna-modeling programs.  YA's modeling
	algorithm is more complex than the W2PV Yagi model, simpler than
	the MININEC model, and more accurate than either.  YA is
	calibrated to NEC, the high-accuracy Numerical Electromagnetics
	Code from the Lawrence Livermore National Laboratory.  YA and
	NEC typically are within 0.05 dB for forward gain, a dB or two
	for F/B, and a couple ohms for input impedance.  Radiation
	patterns calculated by YA and NEC are virtually identical for
	most designs.


	---- USING YA --------------------------------------------------

	        If you have an EGA or VGA display, you can execute YA
	directly.  For an HGC or CGA, first do the following:


	HGC      Load the HERCULES.EXE graphics driver.  To do
	         this, type HERCULES at the DOS prompt.  Since
	         this must be done just once per boot, it's often
	         convenient to load HERCULES from AUTOEXEC.BAT.

	CGA      Load GRAFTABL and GRAPHICS.  You can load
	         them from AUTOEXEC.BAT.  These DOS utilities
	         provide additional CGA fonts and let you print
	         CGA graphics screens.


	        YA stores information for Yagi designs in individual
	files.  Yagi files contain element dimensions, analysis
	frequencies, and other information.  You specify the name of a
	Yagi file when you start YA.  After YA loads the file, you can
	examine or modify the design.  You can save the current design
	in a file at any time.  Yagi files use the extension .YAG.

	        If you know which Yagi file you want, give the filename
	on the YA command line, for example, YA PV4 (the extension isn't
	needed).  Otherwise, type YA and Yagi files in the current
	directory will be listed.  To list Yagi files in a different
	directory, specify the directory name on the command line.

	        Select a file by moving the lightbar with the arrow
	keys, PgUp, PgDn, Home, or End.  Press Enter to select the
	highlighted file.  Alternatively, you can enter a filename by
	typing it.  As you type, the lightbar moves to the first
	filename that matches the characters entered.  Press Enter
	whenever the desired file is highlighted.




				       1

	        Select "Other" to enter a file or directory name not
	listed.  If you enter a directory containing Yagi files, YA
	lists them and you can select one.

	        Press Esc to hide the Main Menu to view the whole
	screen.  Press Esc to return to the Main Menu from a submenu.
	You can also return by pressing the command key a second time
	(but not from Save).  This feature is handy when making a quick
	check.

	        You can terminate data entry and return to the Main Menu
	with one keystroke by pressing Esc instead of Enter.  If you do
	this, whenever you return to the submenu the cursor will be
	positioned at the item last entered.  This makes it easy to
	change a parameter repeatedly to experiment with its effect.

	        You can exit most submenus (not Save or Notes) by
	pressing a valid command key.  YA will execute the command
	immediately, bypassing the Main Menu.  This is a quick way to go
	from one submenu to another.  Whenever you press a command key
	during data entry, YA accepts the data and then executes the new
	command.

	        Use an arrow key with numerical input to enter data and
	simultaneously move the cursor up, down, right, or left to
	another item.  Use the spacebar to enter data without advancing
	to another item.  This is particularly useful with the Match
	Menu and Bracket Menu to change a parameter value repeatedly to
	experiment with its effect.

	        To reduce screen clutter, YA does not label the numbers
	within Yagi patterns.  They have the following meaning:

	                           Frequency
	                          Forward Gain
	                      Front-to-Rear Ratio
	                        Input Impedance
	                      Standing-Wave Ratio
	                        Elevation Angle

	        YA defaults to a generalized definition of front-to-back
	ratio described in the next section.  YA displays elevation
	angle only for Yagis over ground.

	        The notation 12.7-j15.4 means a resistance of 12.7 ohms
	in series with a reactance of -15.4 ohms.  Z stands for
	impedance.  The letter w appended to boomlength means
	wavelengths.  The path and name of the current Yagi file appear
	in the lower-right screen corner.

	        Although YA doesn't require a math coprocessor, it will
	run up to twenty times faster when one is present.  YA will run
	several times faster if you disable your memory manager.




				       2

	---- F/B AND F/R -----------------------------------------------

	        YA uses a generalized notion of front-to-back ratio as a
	measure of pattern quality.  Conventional F/B is the ratio of
	forward power (at 0 degrees) to power radiated in the opposite
	direction (at 180 degrees).  YA's generalized F/B is the ratio
	of forward power to the peak power in the region 90 to 180
	degrees to the rear of the antenna.  This pattern-quality
	measure is called front-to-rear ratio.  The F/R backlobe region
	is the rear half-plane for azimuth patterns and free-space
	elevation patterns.  For elevation patterns of Yagis over
	ground, the backlobe region begins at the rear horizon and
	extends to the zenith.  In general, the F/R figure differs in
	each analysis plane.

	        Yagi designs maximizing conventional F/B may have large
	backlobes at angles other than 180 degrees.  These backlobes can
	cause unwanted signal pickup, but F/R takes them into account.
	YA uses F/R by default.  Use the Options Menu to select
	conventional F/B.


	---- FREQUENCY MENU --------------------------------------------

	        YA models Yagi designs at a spot frequency or over a
	frequency band.  You specify a single analysis frequency for
	spot-frequency designs, and low, middle, and high frequencies
	for designs covering a band.  YA models Yagis to 2 GHz.

	        You can add, change, or delete analysis frequencies with
	the Frequency Menu.  You must use one or three frequencies--YA
	doesn't allow two.  To change to a spot-frequency design, enter
	zero for the low or high frequency.


	---- HEIGHT MENU -----------------------------------------------

	        Use the Height Menu to specify antenna height above
	ground.  YA orients Yagis for horizontal polarization when
	modeling over ground.  Set height to zero to model a Yagi in
	free space.  YA computes forward gain, F/R, and the azimuth
	pattern at the elevation angle specified.

	        YA takes into account mutual impedances between Yagi
	elements and their ground images.  This lets you see the effect
	of ground proximity on azimuth patterns and input impedance.
	However, YA models perfectly conducting ground, not real earth
	with finite conductivity and dielectric constant.  Yagis over
	real earth may have several dB less gain overhead and up to 1 dB
	less gain near the horizon than the figures YA computes.
	Elevation-pattern nulls may be less deep.  Nevertheless, you can
	use YA to make accurate relative comparisons among Yagi designs
	over ground.




				       3

	---- ELEMENTS MENU ---------------------------------------------

	        Use the Elements Menu to change element positions and
	lengths.  YA displays element half-length, the distance from the
	center of the boom to element tip.  For tapered elements YA
	displays the lengths of electrically equivalent untapered
	elements.  These are not physical lengths and should not be used
	for antenna construction.  Use the Taper Menu to inspect and
	change physical lengths of tapered elements.

	        YA can model Yagis with up to 17 elements.  Use the Ins
	and Del keys to add or delete elements.  Press Del to delete the
	element at the cursor.  Press Ins to add an element below the
	cursor.  When you add or delete an inner element, YA respaces
	elements to avoid bunching or gaps.  When you add or delete an
	end element, YA does not respace and the boomlength changes.

	        YA expects every Yagi to have a reflector element.  You
	can model two-element Yagis with a driven element and director
	by placing a dummy reflector a great distance behind the two
	active elements.  This arrangement will satisfy YA while having
	negligible effect on the response of the two-element array.

	        YA accounts for antenna losses due to imperfect element
	conductivity and skin effect.  These losses usually are small
	for tubing elements at HF, but they can be significant for rod
	elements at VHF/UHF.  YA assumes all elements are made of 6061-
	T6 aluminum alloy.  6061-T6 material has a volume resistivity
	23% higher than that of 6063-T832 alloy and 51% higher than that
	of pure aluminum.


	---- TAPER MENU ------------------------------------------------

	        Fast Yagi-modeling algorithms represent each element as
	a thin cylinder of constant diameter.  A tapering algorithm is
	necessary to convert elements of tapered telescoping tubing to
	untapered cylindrical equivalents.  For practical purposes,
	tapered and untapered elements are electrically equivalent when
	their self-impedances are equal.  Tapered elements are always
	physically longer than their untapered equivalents.  Tapering
	must be accurately modeled to realistically characterize HF
	Yagis.

	        YA uses a modified version of the tapering algorithm
	developed by James Lawson, W2PV, from the ARRL book "Yagi
	Antenna Design."  The modified algorithm yields untapered
	equivalents with self-impedances much closer to those of the
	tapered originals.  It also better predicts the real-world
	performance of Yagis with heavily tapered elements.

	        YA can model Yagis with up to eight taper sections.  Use
	the Taper Menu to change the diameter or length of any section.
	For any length change except to the tip section itself, YA
	readjusts tip length to maintain an electrically equivalent
	design.  Use the Ins and Del keys to add or delete taper

				       4

	sections.  You can enter a taper length of zero for elements
	that don't use a particular tubing diameter.


	---- BRACKET MENU ----------------------------------------------

	        A conductive element-to-boom mounting bracket increases
	element effective diameter at the bracket.  The amount of
	increase depends on the size and shape of the bracket.  YA uses
	the equations of D. Jaggard to model flat, rectangular mounting
	plates and Hy-Gain element clamps.  For details of the method,
	see the ARRL book "Physical Design of Yagi Antennas" by Dave
	Leeson, W6QHS.

	        Use the Bracket Menu to define or modify a mounting
	bracket.  Select bracket type with the tab key.  After you enter
	bracket dimensions, YA calculates the length and diameter of an
	equivalent taper section.  The length of the section is the
	half-length of the bracket.  Its diameter is electrically
	equivalent to the element and bracket combined.

	        When you return to the Main Menu, YA updates all
	elements of the current design with the new taper section.
	Whenever the length of the existing first taper section is less
	than 5% of the element half-length, YA assumes that the section
	already represents a mounting bracket.  YA will modify the
	section instead of adding a new one.

	        If you enter zero for a bracket dimension so that YA
	lists "None" for the equivalent taper, when you return to the
	Main Menu YA removes the first taper section if it represents a
	mounting bracket (length less than 5% of the element half-
	length).

	        If the Yagi uses mounting brackets of more than one
	size, calculate equivalent taper sections with the Bracket Menu
	and add them by hand to individual elements with the Taper Menu.
	(YA uses reflector tapering to calculate the numbers displayed
	in the Bracket Menu.  You may need to temporarily modify the
	taper schedule of this element to do calculations for other
	elements.)  Use a taper length of zero for elements that don't
	use a particular taper diameter.

	        To avoid disrupting a complex taper schedule entered by
	hand, YA will not update the taper schedule when you leave the
	Bracket Menu if the length of the first taper section is zero
	for any element.  It also won't update if some elements have
	mounting brackets and others do not.

	        The length of a mounting bracket is its dimension along
	the element.  Enter the total length (both sides of the boom).
	The width of a bracket is its dimension perpendicular to the
	element.  The thickness of a Hy-Gain clamp is the total
	thickness of the flat part.



				       5

	        It's important to take element mounting into account
	when modeling Yagis.  Large mounting brackets may significantly
	alter antenna characteristics.  In extreme cases they can move a
	desired response completely outside a band.  Small brackets can
	upset a carefully optimized pattern at a spot frequency.
	However, mounting methods that use compact hardware no larger
	than the element diameter generally require no correction.


	---- BOOM COMPENSATION -----------------------------------------

	        When an element is close to or passes through a
	conductive boom, its electrical length changes.  YA does not
	model this boom effect, but you can use the information in this
	section to compensate manually.  All correction values apply to
	element half-lengths.  Apply the corrections by increasing
	calculated element lengths when constructing a Yagi.
	Conversely, to model boom effects you must shorten measured
	element lengths.

	        For elements mounted on flat plates in contact with a
	boom, W2PV found that element half-lengths should be corrected
	by 3% of the boom diameter.  He states that this small effect
	diminishes rapidly as the element is spaced away from the boom,
	even by a small distance.

	        For noninsulated through-the-boom mounting, measurements
	by Guenter Hoch, DL6WU, were curve-fit by Ian White, G3SEK, to
	yield the following boom-correction formula:

	               C = (12.5975 - 114.5 * B) * B * B

	        C is the element half-length correction and B is boom
	diameter, both in wavelengths.  * means multiply.  For example,
	a 0.01-wavelength-diameter boom requires element half-lengths to
	be corrected by 0.00115 wavelength.  The experimental data
	underlying this formula came from booms with diameters smaller
	than 0.055 wavelength; the formula isn't valid for larger booms.
	G3SEK says that the correction required for insulated through-
	the-boom mounting is close to 50% of C.


	---- MATCH MENU ------------------------------------------------

	        The Match Menu lets you design a variety of matching
	networks.  Use the tab key to select one of the following
	network types:


	1.  Perfect Match

	        The perfect match is an idealized matching network.
	Because it's always perfectly matched at one frequency, it's
	very handy.  You can set this frequency in the Match Menu.  SWR
	is always 1 at the match frequency.  YA uses the antenna input
	impedance at the match frequency as the SWR reference impedance

				       6

	at all frequencies.  This effectively models a perfectly
	broadband matching network.  Therefore, SWR variation using the
	perfect matching network reveals the inherent impedance-
	bandwidth properties of the antenna.


	2.  Hairpin Match

	        The hairpin match is an L-network using distributed
	reactances.  The driven element is shortened from its resonant
	length to raise the equivalent parallel input resistance to that
	of the feedline.  The hairpin acts as a shunt inductance to
	cancel the capacitive reactance of the shortened driven element.
	Hairpin matches are commonly fed with coax through a balun.  YA
	models the hairpin as a transmission line of parallel rods.

	        You specify rod diameter, rod length, and center-to-
	center rod spacing.  You can also specify balun-lead length.
	Enter the length of one lead from the axis of the balun to the
	element-attachment point.  YA assumes the leads use #12 wire.
	At HF, YA models the leads as fanning out from a spacing of 1.5"
	at the balun to the hairpin-rod spacing at the element.  For
	frequencies above 30 MHz, YA assumes the leads fan out from
	0.15".  This lead spacing is typical of 3/8"-diameter coax
	(presumably loaded with a few ferrite beads).

	        You can specify the shunt capacitance between driven-
	element halves.  This is particularly useful with Hy-Gain
	element clamps.  Use 26.5 pF for 20-meter clamps and 9.5 pF for
	15- and 10-meter clamps.

	        Hy-Gain calls their version of the hairpin match a Beta
	match.  It uses two rods which straddle the boom and a shorting
	strap that connects all three together.  The presence of the
	boom has a negligible effect on hairpin inductance, so a Beta
	match is electrically equivalent to a conventional hairpin
	match.

	        NOTE:  When using a hairpin match, measure driven-
	element half-length from the point where the feedline and
	hairpin attach to the element, not from the center of the boom.


	3.  Gamma Match

	        YA uses equations developed by Harold Tolles, W7ITB, to
	model gamma matches.  You specify gamma-rod diameter, rod
	length, center-to-center spacing from the driven element, and
	series capacitance.  To model lead inductance, specify the lead
	length from the gamma rod to the coax connector.  YA assumes the
	lead uses #12 wire.  When the lead runs parallel to the driven
	element, include its length as part of the gamma rod rather than
	specifying it separately.




				       7

	4.  T Match

	        A T match is a balanced gamma match.  Rod length and
	capacitance values apply for each side of the driven element.
	Some T matches are fed with 50-ohm coax through a 4:1 balun.
	Enter a feed impedance of 200 ohms for these systems (which
	often have negligible lead length).  You can also feed a T match
	with wire leads from a 1:1 balun.  YA makes the same assumptions
	about these balun leads as it does for a hairpin match.  YA
	assumes the distance between T-match rod ends is half their
	distance to the driven element.  To model a T match without
	capacitors, enter a high capacitance value.  To model a folded
	dipole, extend the T-match rod to the end of the element.

	        Gamma- and T-match rods increase the effective diameter
	of the inner part of a driven element.  Because YA does not
	model this effect, you may need to compensate by increasing
	driven-element length when constructing a Yagi.

	        YA uses a velocity factor of 0.975 for the transmission
	lines formed by gamma- or T-match rod and driven element,
	hairpin rods, and balun leads.  For driven-element diameter, YA
	uses a weighted logarithmic average of the diameters of the
	taper sections spanned by gamma- or T-match rods (diameters are
	weighted by taper-section length).  YA draws rod length to scale
	on the Yagi sketch, but not rod spacing.

	        Matching-network performance depends critically on a
	number of physical parameters that are difficult to measure and
	to model accurately.  Calculated and actual matches may differ
	due to input-impedance modeling error, series- or shunt-
	capacitance estimation error, lead-spacing variation, proximity
	of other antennas or guy wires, etc.  When constructing a Yagi,
	always make the matching network adjustable!


	---- SAVE MENU -------------------------------------------------

	        Use the Save command to save the current Yagi design.
	You can specify path and filename.  If you enter the name of a
	Yagi file that already exists, YA asks permission before
	overwriting it.  For fast periodic saves, press Enter to
	overwrite the last file saved (YA doesn't ask permission).  When
	no file has been saved, YA saves the design in SAVE.YAG.  YA
	does not save matching networks or mounting-bracket dimensions.

	        In case you forget to save a design, YA automatically
	saves the current design in the file OUT.YAG whenever you exit
	the program.  You can recover the design by specifying OUT.YAG
	as an input file.







				       8

	---- ALGORITHM LIMITATIONS -------------------------------------

	        YA closely predicts actual antenna performance as long
	as you accurately characterize element tapering and mounting and
	you follow the guidelines in this section.

	        YA is calibrated to NEC, the Numerical Electromagnetics
	Code.  MININEC-based antenna-analysis programs may give
	different results.  The MININEC algorithm has an inherent
	frequency-offset error.  MININEC gives results similar to those
	of YA and NEC but at a frequency up to 2% higher, depending on
	element diameter.

	        YA closely tracks NEC for element diameters up to 0.01
	wavelength (0.27" at 432 MHz).  Yagis with thicker elements may
	exhibit some frequency offset from calculated designs, although
	YA gives reasonable agreement with NEC for diameters up to about
	0.04 wavelength.

	        YA uses a narrowband modeling algorithm.  Accuracy may
	degrade at frequencies more than about 5% away from the central
	design frequency.

	        YA models with input impedances of a few ohms are not
	likely to be accurate.  At these impedance levels element
	currents are very large and fields nearly cancel.  This
	condition greatly magnifies small model inaccuracies.  Low-
	impedance Yagis should be avoided for practical reasons as well.
	Dimensions become critical, skin effect can cause considerable
	loss, impedance matching becomes difficult, and bandwidth is
	severely restricted.

	        Input-impedance accuracy decreases for maximum-gain or
	long-boom designs.  YA is typically a couple ohms high for
	maximum-gain designs with impedances under 10 ohms.  YA is
	typically a few ohms low for designs with a dozen or more
	elements and impedances in the 20- to 30-ohm range.

	        Modeling accuracy may degrade for elements spaced closer
	than about 0.05 wavelength.  In practice, HF elements spaced
	this close may move enough in the wind to affect the response of
	critical designs.  Accuracy may decrease somewhat for Yagis with
	element half-lengths shorter than about 0.19 wavelength.
	Elements this short normally aren't used for designs of 17 or
	fewer elements.

	        To prevent gross modeling errors, YA won't let you enter
	element half-lengths shorter than 0.15 wavelength or longer than
	0.3 wavelength.  It won't let you position elements closer than
	0.03 wavelength.  Finally, it won't let you enter taper
	diameters greater than 0.05 wavelength.






				       9

	---- NOTEPAD ---------------------------------------------------

	        You can enter, edit, and display design notes with the
	Notes command.  YA displays the Yagi title at the top of the
	notepad and you can edit it, too.  The title and notes are saved
	in all output files.

	        The notepad editor automatically wraps words within a
	paragraph.  A blank line or a line with leading space begins a
	new paragraph.  Use the arrow keys, Home, End, PgUp, and PgDn to
	move the cursor.  Use Del or Backspace to delete characters and
	Alt-D to delete a line.  Use PrtSc to print the notepad screen.


	---- GRAPHS ----------------------------------------------------

	        YA graphs forward gain, F/R, SWR, and impedance curves
	versus frequency.  Regular command keys are active while viewing
	graphs.  For example, you can press M and G to alternate between
	the Match Menu and graphs when adjusting a matching network.  F5
	changes screen colors, while PrtSc prints the screen.

	        YA scales graphs automatically.  The F/R or F/B curve
	reflects the backlobe region selected in the Options Menu.  The
	impedance curve graphs input resistance.


	---- PATTERNS --------------------------------------------------

	        YA displays patterns using the standard ARRL log-dB
	polar scale.  Half-scale is about 12 dB down and quarter-scale
	is about 24 dB down.  You can directly compare YA patterns with
	those in ARRL publications since both use the same scale.  To
	reduce screen clutter, YA draws pattern sketches without grids
	or scale markings.  The sketches have 5-degree resolution.

	        Use the Plot command to generate high-resolution
	patterns with grids, scale markings, and annotation.  YA
	calculates these patterns at the middle analysis frequency with
	1-degree resolution.  The Plot command generates a plot file and
	then displays it.  YA saves patterns in files so that you can
	review and compare them later.  A plot file uses the Yagi
	filename and the extension .PLT.  If you plot, change antenna
	geometry, and press P again, YA overwrites the plot file with
	new patterns.  But if you press Alt-P, YA generates a new plot
	file.  Each new file has an incrementing digit appended to its
	name.  Use Alt-P to avoid overwriting plot files generated
	earlier in a session.  (For both P and Alt-P, YA writes a plot
	file only when the pattern has changed.)

	        You can review a plot from DOS by typing YA PLOT.  This
	bypasses the analysis part of YA and lists plot files in the
	current directory.  Specify a directory name to list plot files
	in a different directory.  You can specify the name of a plot
	file, for example, YA PLOT PV4, to display a pattern
	immediately.

				       10

	        Use the O key to overlay two patterns.  YA displays
	filenames instead of plot titles for overlays.  YA coordinates
	overlay annotation with patterns by color for EGA/VGA systems.

	        YA identifies free-space patterns as E-Plane or H-Plane.
	It uses the annotations Azimuth or Elevation for over-ground
	patterns.

	        Dots in the sparse radial lines are spaced 2 dB apart.
	Dots in the outer two circles are spaced 1 and 2 degrees apart.
	These calibrations allow you to read directivity values from
	plots with good accuracy.

	        YA plots are perfectly circular on monitors with
	standard 4:3 aspect ratio.  Adjust your monitor's vertical-
	height control to correct elliptical plots.


	---- OPTIONS MENU ----------------------------------------------

	        The Options Menu lets you control some additional
	aspects of YA.

	        The E-plane is the plane containing Yagi elements.
	Select this plane to analyze the azimuth pattern of a Yagi over
	ground.  The H-plane is the plane perpendicular to the elements.
	Select this plane to analyze the elevation pattern of a Yagi
	over ground.

	        YA displays gain figures in dBi by default.  Gain in dBi
	is antenna response compared with that of an isotropic radiator
	in free space.  An isotropic antenna radiates uniformly in all
	directions.  Select dBd to compare antenna response with that
	broadside to a free-space, half-wave dipole.  Gain figures are
	2.15 dB lower when expressed in dBd.

	        YA uses a backlobe region of 90 to 180 degrees for the
	pattern-quality figure by default (F/R).  For conventional F/B,
	select a backlobe region of 180 degrees.

	        YA defaults to a 24-pin printer.  Select Laser for
	DeskJet printers.  YA does not print color images.

	        YA uses units of inches by default.  Select mm to use
	millimeters.  YA reads Yagi files defined either way and
	converts file dimensions to the units currently selected.

	        YA automatically saves all settings in the Options Menu
	(and all screen colors for EGA/VGA systems) when you exit the
	program.  The settings are saved in the YA.INI initialization
	file.  If this file is present when YA begins execution, it sets
	the options and colors accordingly.  Delete YA.INI to use
	default options and colors.




				       11

	---- SCREEN COLORS ---------------------------------------------

	        Press F5 to change screen colors for EGA and VGA
	systems.  Use the left-arrow and right-arrow keys to select a
	screen item (an item blinks once when selected).  Then use the
	up-arrow and down-arrow keys to cycle forward and backward among
	the 64 available colors.  Press S to save color codes in the
	YA.INI file.  Use F5 to change colors for any screen.  YA saves
	colors for all screens whenever it saves those for one.


	---- SCREEN PRINT ----------------------------------------------

	        YA prints monochrome screen images on most printers (but
	not PostScript printers).  For EGA, VGA, and HGC systems, use
	the Options Menu to specify and save printer type.  For CGA
	systems, load the DOS GRAPHICS program before starting YA.  See
	your DOS manual to specify printer type when using GRAPHICS.
	Press PrtSc to print any screen.






































				       12

	                             INDEX


	#12 wire  7
	5% of the element half-length  5
	6061-T6  4
	6063-T832  4

	Accuracy  1, 9
	Algorithm Limitations  9
	Alt-D  10
	Alt-P  10
	Aluminum  4
	Always make the matching network adjustable!  8
	Arrow keys  1, 10
	AUTOEXEC.BAT  1
	Azimuth  11

	Backlobe region  3
	Backspace  10
	Balun  8
	Balun-lead length  7
	Blink  12
	Boom Compensation  6
	Boom-correction formula  6
	Bracket Menu  5

	CGA  1, 12
	Color  10, 11
	Command line  1
	Conductivity  3
	Conventional F/B  3
	Current directory  1

	DBd  11
	DBi  11
	Del  4, 10
	Dielectric constant  3
	Directory  1, 10
	DL6WU  6
	Driven-element diameter  8
	Dummy reflector  4

	E-Plane  11
	Effective diameter  8
	EGA  1, 11, 12
	Element conductivity  4
	Elements Menu  4
	Elevation  11
	Elevation angle  3
	End  1, 10
	Enter  1, 2, 8
	Esc  2

	F/B  3
	F/R  3

				       13

	F5  10, 12
	Folded dipole  8
	Forward gain  1
	Free space  3
	Frequencies above 30 MHz  7
	Frequency band  3
	Frequency-offset error  9

	G3SEK  6
	Gamma match  7
	GRAFTABL  1
	GRAPHICS  1, 12
	Graphs  10
	Ground  3

	H-Plane  11
	Hairpin match  7
	Height Menu  3
	HERCULES.EXE graphics driver  1
	HGC  1, 12
	Hide the Main Menu  2
	High-resolution patterns  10
	Highlighted file  1
	Hoch  6
	Home  1, 10
	Hy-Gain element clamps  7

	Idealized matching network  6
	Impedance  2, 3, 4, 6, 8, 9, 10
	Initialization file  11
	Ins  4
	Insulated through-the-boom mounting  6
	Isotropic antenna  11

	Jaggard  5

	Lawrence Livermore National Laboratory  1
	Lawson  4
	Lead length  7
	Leeson  5
	Lightbar  1
	Logarithmic average  8

	Main Menu  2
	Match frequency  6
	Match Menu  6
	Math coprocessor  2
	Memory manager  2
	MININEC  1, 9
	Mounting bracket  5
	Mutual impedance  3

	NEC  1, 9
	Notes  10
	Numerical Electromagnetics Code  1, 9


				       14

	Options Menu  11
	Other  2
	OUT.YAG  8
	Overlays  11

	Peak power  3
	Perfect match  6
	PgDn  1, 10
	PgUp  1, 10
	Plot file  10
	PLT  10
	Polar scale  10
	Polarization  3
	Printer  11, 12
	PrtSc  10, 12

	Quick check  2

	Respaces elements  4
	Return to the Main Menu  2
	Rod diameter  7
	Rod length  7
	Rod spacing  7

	Save Menu  8
	SAVE.YAG  8
	Self-impedance  4
	Shunt capacitance  7
	Skin effect  4, 9
	Spacebar  2
	Spot frequency  3
	Submenu  2
	SWR  6
	SWR reference impedance  6

	T match  8
	Tab key  5, 6
	Taper Menu  4
	Tapering algorithm  4
	Terminate data entry  2
	Through-the-boom mounting  6
	Tolles  7
	Two-element Yagis  4

	Velocity factor  8
	VGA  1, 11, 12

	W2PV  1, 4, 6
	W6QHS  5
	W7ITB  7
	White  6

	YA PLOT  10
	YA.INI  11, 12
	Yagi files  1
	Yagi title  10

	Z  2
				       15

