f0 = 5760 # [MHz] Frequency
N = 10 # Number of slots
Z_F0=120.0*pi
c0=2.997831e8
lambda_0= C0/f0/1e6
print 'Freespace wavelength in: %6.2f mm' % (lambda_0*1e3)
print 'Cutoff value for a: %6.2f mm' % (lambda_0*1e3/2)
print 'Optimum width for a: %6.2f mm' % (lambda_0*sqrt(3.)*1e3/2)
Freespace wavelength in: 52.05 mm Cutoff value for a: 26.02 mm Optimum width for a: 45.07 mm
a = 43.8 # [mm] waveguide width
b = 23.9 # [mm] waveguide height
lambda_c=2.0*a/1e3
lambda_h= lambda_0 / sqrt(1.0 - (lambda_0/lambda_c)**2)
print 'lambda_h: %3.2f mm' % lambda_h
g= 10*log10(N * lambda_h/lambda_0)
print 'Approximate antenna gain: %3.1f dBi' % g
dtheta=50.7 * lambda_0 / N / lambda_h * 2.0
print 'Beamwidth: %3.1f deg' % dtheta
# calculate offset from center
x = 1e-3 * a/pi*arcsin(sqrt(lambda_0*b/(N*3.5*lambda_h*a*cos(pi*lambda_0/2.0/lambda_h)**2)))
print 'slot offset from center: %6.2f mm' % (x*1e3)
# slot width
sb = lambda_h / 30
print 'slot width: %6.2f mm' % (sb*1e3)
# compute slot length
# use figure 7 and interpolate
x_23cm = f0/1270 * x
sx=[ 0, 8.6, 10, 20, 29 ] # x in mm
sl=[ .475, .491, .494, .519, .55] # L/lambda_0
L = interp(x_23cm*1e3,sx,sl)
print 'slot length: %6.2f mm' % (L*1e3*lambda_0)
# calculate slots
print ''
print ' Slot No Distance'
print '----------------------------------------'
for i in range(N-1):
print ' %d %6.2f mm' % ( i+1 ,1e3*(lambda_h/4+lambda_h/2*i) )
lambda_h: 0.07 mm Approximate antenna gain: 11.0 dBi Beamwidth: 8.1 deg slot offset from center: 5.08 mm slot width: 2.21 mm slot length: 27.50 mm Slot No Distance ---------------------------------------- 1 16.58 mm 2 49.73 mm 3 82.89 mm 4 116.05 mm 5 149.20 mm 6 182.36 mm 7 215.51 mm 8 248.67 mm 9 281.83 mm