.PS
cct_init

# Usual defs...
qrt=dimen_/4;
hlf=dimen_/2;
dim=dimen_;

linethick_(1.5)
line from (0,0.1*dim) up_ 2* dim
Dtop:Here
line from (0,-0.1*dim) down_ 2* dim
Dbot:Here
linethick_() #default 
dimension_(from Dtop to Dbot,-1.5*dim,"L",hlf,5mm__)

# y is at (0,dim)
move to (0.05*dim,0.9*dim)
ts=0.1*dim
right_; line to rvec_(0,2*ts) then to rvec_(-ts,2*ts) then to rvec_(-ts,0) \
  then to Here
DyBot:(0,-Here.y)
dimension_(from (0,0) to (0,Here.y+ts),hlf,$y$,qrt)
dimension_(from DyBot to DyBot-(0,2*ts),-hlf,$dy$,0.45*dim)

move to (0.05*dim, -1.1*dim)
right_; line to rvec_(0,2*ts) then to rvec_(-ts,2*ts) then to rvec_(-ts,0) \
  then to Here

rl=3*dim;
ra=atan2(1,3)
P:(rl*cos(ra),rl*sin(ra))
line from (0,0) to P; "$r_0$" at last line.center below_ ljust_
line from (0,dim) to P+(0,dim); "$r=r_0 - y\cos\theta$" at last \
  line.center below_ ljust_
line from (0,-dim) to P-(0,dim); "$r^\prime=r_0 + y \cos\theta$" at last \
  line.center below_ ljust_
"(P) at $\infty$" at P+(hlf,0) ljust_


hyp=1*dim*cos(ra);
line dotted from (0, dim) down_ hyp*cos(ra) right_ hyp*sin(ra)
dimension_(from Here to (0,0), qrt)
"$y\cos\theta$" at (-0.2*dim, -0.35*dim) rjust_

#arc <-> cw radius 0.5*dim from (0,1.5*dim) to \
#  (0, 1*dim)+(hlf*cos(ra), hlf*sin(ra))
#"$\theta$" at (0.2*dim, 1.2*dim)  
move to (0,dim)
Y:Here
rl = 0.75*dim
arcdimension_(cw radius rl from Y+(0,rl) to \
  Y+(rl*cos(ra), rl*sin(ra)),,"$\theta$",2mm__ )  


spline from Dtop right_ 0.6*dim down_ dim then right_ \
  0.15*dim down_ dim dashed
spline from Dbot right_ 0.6*dim up_ dim then right_ \
  0.15* dim up_ dim dashed
  right_
"$I=I_0\sin\beta(L/2-y)e^{j\omega t}$" at (0.5*dim,2.2*dim) ljust_

# line -> from (hlf,2.0*dim) down_ 0.2*dim left_ 0.3*dim

right_
"$I=I_0\sin\beta(L/2+y)e^{j\omega t}$" at (hlf,-1.5*dim) ljust_

"\tiny Sinusoidal" at (2.5*dim,-2.5*dim)
.PE