.PS
cct_init

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

Org:Here
dot(,1mm__)
"1" at Org+(-3mm__,4mm__)
L1:line from Org right_ 4*dim
dot(,1mm__)
"2" at L1.end+(3mm__,4mm__)
line from L1.end right_ dim; " $\theta=0^\circ$" ljust_
move down 2.5*dim
dimension_(from (L1.start,Here) to (L1.end,Here),,$d=\lambda/2$,13mm__)
line from L1.start left 

linethick_(2)
#linethick_(1.5)
line from (0,-dim) to (0,dim)
line from L1.end+(0,-dim) to L1.end+(0,dim)
linethick_();

# Define \alpha: say 30\degrees from zenith...
len = 1.5*dim
theta = pi_/3 # complement.
line from Org to (len*cos(theta),len*sin(theta))
# Neat trick to define arcspec: produces an error, but works :-)
A1:arcd((0,0),1.25*dim,60,90,invis)
arcdimension_(A1,,$\alpha$,2.5mm__,,<-)

# Define \theta
theta = pi_/6
line from L1.center to L1.center+(len*cos(theta),len*sin(theta))
A1:arcd(L1.center,1.25*dim,0,30,invis)
arcdimension_(A1,,$\theta$,2.5mm__,,->)

# Array Pattern
move to L1.center
for theta = 0 to twopi_ by 0.05 do { # roughly 100 points...
  e = abs(cos(pi_/2*cos(theta)))
  line to L1.center+(e*cos(theta),e*sin(theta))
}

# Element pattern, complementary angle, so
# sin(\alpha)=cos(90-\alpha=\theta) :-) (moving centre to L1.c)
move to L1.center
for theta = 0 to twopi_ by 0.05 do {
  e = abs(cos(theta))
  line to L1.center+(e*cos(theta),e*sin(theta))
}

# Pattern Multiplication of the above...
move to L1.center
for theta = 0 to twopi_ by 0.05 do {
  e = abs(cos(theta)*cos(pi_/2*cos(theta)))
  line to L1.center+(e*cos(theta),e*sin(theta))
}

# Enforce direction vectors: 
right_
# and compute lines. Try this with a mouse...
"$E=\displaystyle E_0\left[\cos\left(\frac{\pi}{2}\cos\theta\right)\right]$" \
   ljust at L1.center+(15mm__,25mm__) 
# choose 75\degrees   
theta = dtor_*75
e = abs(cos(pi_/2*cos(theta)))
line outlined "red" -> to L1.center+(e*cos(theta), e*sin(theta))   

"$E=k\sin\alpha$" at L1.center+(1.5*dim,1.2*dim) ljust
theta = dtor_*45
e = abs(cos(theta))
line outlined "red" -> to L1.center+(e*cos(theta), e*sin(theta))   

# linebreaking this, even with \ introduces space!!!
"$E=\displaystyle E_0\left[\cos\left(\frac{\pi}{2}\cos\theta\right)\right]\times k\sin\alpha$" \
   at L1.center+(dim,-2*dim) ljust
theta = dtor_*(-55) # Must bracket: Unitary minus not allowed :-)
e = abs(cos(theta)*cos(pi_/2*cos(theta)))
line outlined "red" -> to L1.center+(e*cos(theta), e*sin(theta))   

"\tiny PatMult" at (4.5*dim,-3*dim)
.PE