# -*- coding: utf-8 -*- VERSION = 20180914 ''' DESCRIPTION This LPDA calculator is based on the design procedure as described by L. B. Cebik, W4RNL (SK) in the 21st edition of The ARRL Antenna Handbook. USAGE See: http://hamwaves.com/lpda/en/index.html COPYRIGHT Copyright (C) 2014-2018 Serge Y. Stroobandt This program is free software: you can redistribute it and/or modify it under the terms of the GNU General Public License as published by the Free Software Foundation, either version 3 of the License, or (at your option) any later version. This program is distributed in the hope that it will be useful, but WITHOUT ANY WARRANTY; without even the implied warranty of MERCHANTABILITY or FITNESS FOR A PARTICULAR PURPOSE. See the GNU General Public License for more details. You should have received a copy of the GNU General Public License along with this program. If not, see . CONTACT ON4AA xdg-open mailto:$(echo c2VyZ2VAc3Ryb29iYW5kdC5jb20K |base64 -d) ''' ### IMPORTS ### from browser import document from browser.html import OPTION from math import floor, log, sqrt import time ### GLOBALS ### c = 299792458.0 ### FUNCTIONS ### def update_range(event): id = event.target.id.replace('range.','') value = event.target.value document[id].value = value calculate(event) def update_diam_N(event): diam_N = float(document['diam_N'].value) if(document['SI'].checked): document['diam_N'].value = '%.2f' % (diam_N * 25.4) if(document['imperial'].checked): document['diam_N'].value = '%.4f' % (diam_N / 25.4) calculate(event) def subscript(integer): return ''.join([chr(8320+int(i)) for i in str(integer)]) def calculate(event): document['txt'].clear() if(document['SI'].checked): conv = 1.0 unit = 'm' if(document['imperial'].checked): conv = (12 * 0.0254)**-1 unit = 'ft' try: f_1 = float(document['f_1'].value) * 1E6 f_n = float(document['f_n'].value) * 1E6 if(f_n >= f_1): t = time.time() document['txt'] <= 'LPDA — https://hamwaves.com/lpda/ — v{}\n'.format(VERSION) document['txt'] <= time.strftime(' LPDA design %Y-%m-%d %H:%M\n', time.localtime(t)) document['txt'] <= '\nINPUT\n' document['txt'] <= ' Lowest frequency f₁ = %s MHz\n' % document['f_1'].value document['txt'] <= ' Highest frequency fₙ = %s MHz\n' % document['f_n'].value if(document['SI'].checked): diam_N = float(document['diam_N'].value)*1E-3 document['txt'] <= ' Diameter of the shortest element ⌀ = %s mm\n' % document['diam_N'].value if(document['imperial'].checked): diam_N = float(document['diam_N'].value)*0.0254 document['txt'] <= ' Diameter of the shortest element ⌀ = %s inch\n' % document['diam_N'].value Zc_in = float(document['Zc_in'].value) document['txt'] <= ' Characteristic input impedance Zc_in = %.f Ω\n' % Zc_in B = f_n/f_1 document['B'].value = '%.3f' % B tau = float(document['tau'].value) document['txt'] <= ' Taper τ = %.3f\n' % tau sigma_opt = 0.243 * tau - 0.051 document['range.sigma'].max = '%.3f' % sigma_opt document['sigma_opt'].value = '%.3f' % sigma_opt sigma = float(document['sigma'].value) if(sigma > sigma_opt): document['sigma'].value = '%.3f' % sigma_opt document['txt'] <= ' Optimal relative spacing σₒₚₜ = %.3f\n' % sigma_opt document['txt'] <= ' Chosen relative spacing σ = %.3f\n' % sigma document['txt'] <= '\nRESULTING DESIGN\n' cot_alpha = 4 * sigma * (1 - tau)**-1 document['cot_alpha'].value = '%.3f' % cot_alpha B_ar = 1.1 + 7.7 * (1 - tau)**2 * cot_alpha document['B_ar'].value = '%.3f' % B_ar B_S = B * B_ar document['B_S'].value = '%.3f' % B_S N = 1 + log(B_S) / log(tau**-1) if(N-floor(N) > 0.3): N = int(N) + 1 else: N = int(N) document['N'].value = N document['txt'] <= ' Number of elements ⌊N⌉ = %d\n' % N ell = [] ell_tot = 0. document['ell'].clear() document['txt'] <= ' Dipole element lengths:\n' lambda_1 = c / f_1 ell.append(0.5 * lambda_1) ell_tot += ell[0] document['ell'] <= OPTION('ℓ%s = %.3f %s' % ('₁', conv * ell[0], unit), value = 1) document['txt'] <= ' dipole ℓ%s = %.3f %s\n' % ('₁', conv * ell[0], unit) for i in range(1,N): ell.append(tau * ell[i-1]) ell_tot += ell[i] document['ell'] <= OPTION('ℓ%s = %.3f %s' % (subscript(i+1), conv * ell[i], unit), value = i+1) document['txt'] <= ' dipole ℓ%s = %.3f %s\n' % (subscript(i+1), conv * ell[i], unit) document['ell'] <= OPTION('ℓₜₒₜ = %.3f %s' % (conv * ell_tot, unit)) document['txt'] <= ' Sum of all dipole lengths ℓₜₒₜ = %.3f %s\n' % (conv * ell_tot, unit) d = [] L = 0. document['d'].clear() document['txt'] <= '\n Distances between the element centres\n' document['txt'] <= ' and their position along the boom:\n' for i in range(N-1): d.append(0.5 * (ell[i] - ell[i+1]) * cot_alpha) L += d[i] document['d'] <= OPTION('d%s,%s = %.3f %s, i.e. ℓ%s @ %.3f %s' % (subscript(i+1), subscript(i+2), conv * d[i], unit, subscript(i+2), conv * L, unit), value = i+1) document['txt'] <= ' d%s,%s = %.3f %s, i.e. ℓ%s @ %.3f %s\n' % (subscript(i+1), subscript(i+2), conv * d[i], unit, subscript(i+2), conv * L, unit) document['L'].value = '%.3f %s' % (conv * L, unit) document['txt'] <= ' Boom length L = %.3f %s\n' % (conv * L, unit) ell_Z_term = 0.125 * lambda_1 document['ell_Z_term'].value = '%.3f %s' % (conv * ell_Z_term, unit) document['txt'] <= '\n Length of the terminating stub ℓ_Zterm = %.3f %s\n' % (conv * ell_Z_term, unit) #Cebik Zc_N = 120 * (log(ell[N-1] / diam_N) - 2.25) document['Zc_N'].value = '%.1f Ω' % Zc_N sigma_mean = sigma / sqrt(tau) Zc_feed = Zc_in**2 * (8 * sigma_mean * Zc_N)**-1 Zc_feed += Zc_in * sqrt( (Zc_in**2 * 0.015625 * sigma_mean**-2 * Zc_N**-2) +1) document['Zc_feed'].value = '%.1f Ω' % Zc_feed document['txt'] <= ' Required characteristic impedance of the feeder\n' document['txt'] <= ' connecting the elements Zc_feed = %.1f Ω\n' % Zc_feed document['txt'] <= '\nDONATE\n' document['txt'] <= ' If this calculator proved any useful to you,\n' document['txt'] <= ' please, consider making a one-off donation\n' document['txt'] <= ' towards keeping me and the server up and running.\n' document['txt'] <= ' Thank you!' else: raise ValueError except: document['txt'].clear() outputs = ['B', 'sigma_opt', 'cot_alpha', 'B_ar', 'B_S', 'N', 'L', 'ell_Z_term', 'Zc_N', 'Zc_feed'] for i in range(len(outputs)): document[outputs[i]].value = '' document['ell'].clear() document['d'].clear() ### MAIN ### document['brython'].style.display = 'initial' calculate(None) ### EVENT HANDLERS ### inputs = ['f_1', 'f_n', 'diam_N', 'Zc_in'] for i in range(len(inputs)): document[inputs[i]].bind('focus', calculate) document[inputs[i]].bind('input', calculate) document['SI'].bind('change', update_diam_N) document['imperial'].bind('change', update_diam_N) document['range.tau'].bind('change', update_range) document['range.sigma'].bind('change', update_range)