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#!/usr/bin/env python
# calctenna
# antenna calculator
# 2020-12-19
# Oliver Meckmann
import argparse
import unittest
import sys
class Tests(unittest.TestCase):
def test_calc(self):
self.assertEqual(calc(100e6, 0.951),
(2.99792458, 1.49896229, 0.749481145, 0.7127565688949999))
def run_argparse():
argparser = argparse.ArgumentParser()
argparser.add_argument(
'-V',
'--velocity-factor',
metavar='velocity_factor',
default='0.951'
)
argparser.add_argument(
'-q',
'--quiet',
help='print only result',
action='store_true'
)
argparser.add_argument(
'frequency',
metavar='frequency',
help='desired frequency in Hz (e.g. 144800000 or 433e6, ...)',
nargs='?'
)
argparser.add_argument(
'-t',
'--tests',
help='run unit tests and exit',
action='store_true'
)
args = argparser.parse_args()
if not args.frequency:
argparser.print_usage()
return args
def check_input(frequency, velocity_factor):
try:
f = float(frequency)
except:
print("Sorry, frequency input invalid or missing")
return False
if f <= 0.0:
print("Sorry, frequency must be > 0")
return False
try:
V = float(velocity_factor)
except:
print("Sorry, velocity factor input invalid")
return False
if V < 0.0 or V > 1.0:
print("Sorry, velocity factor can only be between 0.0 and 1.0")
return False
return True
def calc(frequency, velocity_factor):
c = 299792458 # speed of light
wavelength = float(c) / float(frequency)
wavelength_2 = wavelength/2
wavelength_4 = wavelength/4
dipole_leg_length = wavelength/4 * float(velocity_factor)
return (wavelength, wavelength_2, wavelength_4, dipole_leg_length)
if __name__ == '__main__':
args = run_argparse()
if args.tests:
# override args for unittest: argv[0] to have name in test output
unittest.main(argv=[sys.argv[0], '--verbose'], exit=True)
if not check_input(args.frequency, args.velocity_factor):
exit()
(wavelength, wavelength_2, wavelength_4, dipole_leg_length) = \
calc(args.frequency, args.velocity_factor)
if not args.quiet:
print("Desired Frequency: " + str(args.frequency) + " Hz")
print("Wavelength: %.3f m" % wavelength)
print("Wavelength / 2: %.3f m" % wavelength_2)
print("Wavelength / 4: %.3f m" % wavelength_4)
print("Velocity factor: " + str(args.velocity_factor))
print("-> Dipole leg length (lambda/4): ", end='')
print("%.3f m" % dipole_leg_length)
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