how to draw a spiral in autocad

You can use AutoCAD because this program knows .dwg format. Also probably you can use .dxf format that a lot of EM software’s can recognize.

Can I just enter the spiral equation and get Autocad to draw the log spiral geometry for me. If not, is there any special software for this purpose?

Added after 6 minutes:

Attached is the .jpg format of the log spiral drawing I am trying to draw. Can anyone teach me how do I generate this gepmetry in *.dwg or *.dfx format.
thks in advance.

you must write a program by youself.

or plot the spiral points one by one.....

You have lot of options...
Use autocad or any good layout editors then export it as DXF file..

Then Simulate using Electromagnetic Simulators like Sonnet, IE3d, etc...

or Completely draw the log spiral layout & simulate in a single tool like AWR Microwave Office (Laout+EM Simulator)....

I attached typical Log spiral DXF file in compressed zip file for you...

do you have the autolisp program of log spiral antenna?

The following routine will draw you a 100-segment Archimedean spiral given by the polar equation

r=A*ang^(1/nn)

where the polar angle "ang" sweeps 0 rad to 3*pi rad.

When you draw the spiral simply select the curve, use "_pedit" command and then "w" to assign a track width.

;This code draws an Archimedean Spiral
(defun c:spiral (/ seg ang cnt rad x y z point)
(setq seg 100) 
(setq nn 0.6)
(setq AA 0.1)
(setq ang (/ (* 3 pi) seg)) 
(setq cnt 0)
(command "_pline")
(repeat (1+ seg)
(setq x (* AA (expt (* cnt ang) (/ 1 nn)) (cos (* cnt ang))))
(setq y (* AA (expt (* cnt ang) (/ 1 nn)) (sin (* cnt ang))))
(setq point (list x y))
(command point)
(setq cnt (1+ cnt))
)
(command "")
(princ)
(command "._zoom" "E")
)

hi ozgur_io

thanks much!
if this code make a planner or linear spiral ?
if we want that this code automatically make a dxf code what should we do?

Above code gives you a 1D spiral curve. However by defining the width you can make it a 2D planar spiral strip.

I'm not an expert on AutoCAD lisp routines so I don't know. I always do it manually...

hi ozgur_io
thanks for your help!

if we can change any arameter in exported object in hfss or not? any way exist?

Once imported, you cannot change any parameter in the layout. You can modify the objects by adding or substracting other objects but you cannot change the spiral parameters.

then i thinks that we should write a parametric Autolisp Code in Autocad in order to have Semi-parametric Simulation in HFSS!

Hi,

I am having difficulties in trying to draw out the geometry of the log spiral antenna. I wanted to produce a mask for the log spiral antenna geometry using matlab program. Can somebody help to write a code.

Thanks!

Linas8
you should only use the method which ozgur_io suggest above!