path: root/calctenna.py

#!/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):
        antenna_data = AntennaData(100e6, 0.951)
        calc(antenna_data)
        self.assertEqual(antenna_data.dipole_leg_length_m, 0.7127565688949999)

class AntennaData():
    def __init__(self, frequency_hz, velocity_factor):
        self.frequency_hz = frequency_hz
        self.velocity_factor = velocity_factor
        # fill me
        self.wavelength_m = 0
        self.wavelength_2_m = 0
        self.wavelength_4_m = 0
        self.dipole_leg_length_m = 0

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_hz, velocity_factor):
    try:
        f = float(frequency_hz)
    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

# fill struct
def calc(antenna_data):
    c = 299792458.0 # speed of light
    antenna_data.wavelength_m = c / antenna_data.frequency_hz
    antenna_data.wavelength_2_m = antenna_data.wavelength_m/2
    antenna_data.wavelength_4_m = antenna_data.wavelength_m/4
    antenna_data.dipole_leg_length_m = antenna_data.wavelength_4_m \
            * antenna_data.velocity_factor

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()

    # check_input OK -> float()
    antenna_data = AntennaData(float(args.frequency), float(args.velocity_factor))
    calc(antenna_data)

    if not args.quiet:
        print("Desired Frequency: " + str(antenna_data.frequency_hz) + " Hz")
        print("Wavelength: %.3f m" % antenna_data.wavelength_m)
        print("Wavelength / 2: %.3f cm" % (antenna_data.wavelength_2_m*100))
        print("Wavelength / 4: %.3f cm" % (antenna_data.wavelength_4_m*100))
        print("Velocity factor: " + str(antenna_data.velocity_factor))
        print("-> Dipole leg length (lambda/4): ", end='')
    print("%.3f cm" % (antenna_data.dipole_leg_length_m*100))