A New Approximate Method for Lightning-Radiated ELF/VLF Ground Wave Propagation over Intermediate Ranges

<div>The (a) amplitude and (b) phase angle of attenuation functions (<i>σ</i> = 0.01 S/m and <i>d</i> = 1500 km). <svg height="11.9316pt" id="M97" style="vertical-align:-3.2957pt" version="1.1" viewbox="-0.0498162 -8.6359 28.7973 11.9316" width="28.7973pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M962 650H739L732 622L760 619C812 613 819 604 798 552C760 457 671 267 606 131H604L511 638H480L237 131H233L183 554C177 607 183 614 226 619L248 622L257 650H24L17 622C88 615 92 611 103 524L173 -11H203L450 491H453L543 -11H575L839 529C882 609 886 613 953 622L962 650Z" id="g113-88"></path></g><g transform="matrix(.0091,0,0,-0.0091,10.777,3.132)"><path d="M969 650H746V617C823 609 825 598 814 540C798 470 743 278 700 144H698C638 319 581 476 525 641H491C440 478 384 317 329 145H327C283 286 245 418 205 553C192 601 192 609 267 617V650H20V617C80 609 98 602 122 522C177 343 233 172 285 -9H321C372 152 428 309 485 485H487C542 330 604 151 660 -9H696C779 269 841 460 862 521C891 599 900 609 969 617V650Z" id="g58-85"></path></g><g transform="matrix(.0091,0,0,-0.0091,18.854,3.132)"><path d="M442 39L431 68C420 63 406 57 394 57C377 57 359 71 359 118V301C359 353 349 393 314 424C291 443 261 451 230 451C171 438 107 401 79 381C59 366 46 355 46 340C46 316 72 295 91 295C106 295 117 303 122 319C131 350 139 371 152 384C163 397 178 404 197 404C246 404 281 365 281 293V278C260 262 186 232 124 213C69 194 41 161 41 112C41 47 92 -12 163 -12C195 -12 243 25 283 51C288 35 293 22 308 7C319 -4 339 -12 354 -12L442 39ZM281 87C262 68 226 51 199 51C169 51 129 74 129 126C129 162 151 181 190 198C211 208 259 229 281 240V87Z" id="g58-95"></path></g><g transform="matrix(.0091,0,0,-0.0091,22.858,3.132)"><path d="M138 535C169 535 191 560 191 589C191 620 168 644 139 644S85 620 85 589C85 560 110 535 138 535ZM257 0V30C192 35 185 43 185 109V453C142 435 94 422 40 414V386C101 378 104 372 104 311V109C104 41 97 35 33 30V0H257Z" id="g58-103"></path></g><g transform="matrix(.0091,0,0,-0.0091,25.251,3.132)"><path d="M303 37L293 66C280 59 256 49 231 49S173 63 173 143V396H281C294 404 298 428 287 439H173V575L158 577L92 509V439H46L17 408L22 396H92V107C92 27 128 -12 192 -12C203 -12 218 -9 237 2L303 37Z" id="g58-114"></path></g></svg> is the attenuation function proposed by Wait [<a href="/journals/ijap/2018/9353294/#B3">3</a>, <a href="/journals/ijap/2018/9353294/#B4">4</a>], accounting for the effect of earth conductivity and curvature. Attenuation function <svg height="14.1649pt" id="M98" style="vertical-align:-5.529pt" version="1.1" viewbox="-0.0498162 -8.6359 16.4298 14.1649" width="16.4298pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M962 650H739L732 622L760 619C812 613 819 604 798 552C760 457 671 267 606 131H604L511 638H480L237 131H233L183 554C177 607 183 614 226 619L248 622L257 650H24L17 622C88 615 92 611 103 524L173 -11H203L450 491H453L543 -11H575L839 529C882 609 886 613 953 622L962 650Z" id="g113-88"></path></g><g transform="matrix(.0091,0,0,-0.0091,10.777,3.132)"><path d="M525 275C525 381 464 451 380 451C338 451 289 439 241 405C158 347 127 277 106 152C51 -168 37 -216 24 -242L28 -257C42 -256 92 -247 117 -222C126 -213 134 -193 150 -69L166 32C184 10 211 -12 245 -12C276 -12 332 8 384 46C458 100 525 176 525 275ZM436 260C436 131 366 41 267 41C246 41 208 51 175 82C181 125 187 162 195 200C220 322 257 400 328 400C398 400 436 338 436 260Z" id="g50-239"></path></g></svg> only accounts the effect of the earth curvature and <svg height="11.927pt" id="M99" style="vertical-align:-3.291101pt" version="1.1" viewbox="-0.0498162 -8.6359 16.6764 11.927" width="16.6764pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M962 650H739L732 622L760 619C812 613 819 604 798 552C760 457 671 267 606 131H604L511 638H480L237 131H233L183 554C177 607 183 614 226 619L248 622L257 650H24L17 622C88 615 92 611 103 524L173 -11H203L450 491H453L543 -11H575L839 529C882 609 886 613 953 622L962 650Z" id="g113-88"></path></g><g transform="matrix(.0091,0,0,-0.0091,10.777,3.132)"><path d="M558 454L532 470C512 451 497 442 465 442C421 442 376 450 318 450C146 450 24 313 24 164C24 46 91 -12 183 -12C317 -12 439 105 439 247C439 306 428 346 382 385L383 389C414 384 450 379 485 379C517 379 539 412 558 454ZM357 273C357 191 313 28 205 28C149 28 111 79 111 160C111 266 175 396 280 396C298 396 328 386 341 357C353 331 357 315 357 273Z" id="g50-240"></path></g></svg> only accounts the effect of the earth conductivity. <svg height="14.1649pt" id="M100" style="vertical-align:-5.529pt" version="1.1" viewbox="-0.0498162 -8.6359 72.298 14.1649" width="72.298pt" xmlns="http://www.w3.org/2000/svg" xmlns:xlink="http://www.w3.org/1999/xlink"><g transform="matrix(.013,0,0,-0.013,0,0)"><path d="M962 650H739L732 622L760 619C812 613 819 604 798 552C760 457 671 267 606 131H604L511 638H480L237 131H233L183 554C177 607 183 614 226 619L248 622L257 650H24L17 622C88 615 92 611 103 524L173 -11H203L450 491H453L543 -11H575L839 529C882 609 886 613 953 622L962 650Z" id="g113-88"></path></g><g transform="matrix(.0091,0,0,-0.0091,10.777,3.132)"><path d="M262 451C169 451 38 375 38 210C38 98 121 -12 261 -12C360 -12 481 64 481 227C481 351 386 451 262 451ZM249 414C337 414 385 320 385 204C385 70 333 25 272 25C189 25 134 117 134 241C134 355 189 414 249 414Z" id="g58-109"></path></g><g transform="matrix(.0091,0,0,-0.0091,15.399,3.132)"><path d="M527 54L498 55C459 56 451 63 451 114V445C436 442 413 438 384 435C353 432 318 430 291 429V402L328 396C361 390 370 387 370 331V101C336 70 300 54 262 54C217 54 173 78 173 166V300C173 361 173 412 176 445C160 442 132 438 105 434C77 431 52 430 29 429V402L59 395C83 390 92 385 92 331V141C92 30 150 -12 218 -12C246 -12 266 -4 295 13C324 29 346 47 370 64V-6L376 -12C396 -7 421 1 448 8C476 15 504 21 527 24V54Z" id="g58-115"></path></g><g transform="matrix(.0091,0,0,-0.0091,20.322,3.132)"><path d="M185 344V453C137 433 92 421 41 413V386C100 378 104 375 104 310V106C104 41 97 35 33 30V0H268V30C190 35 185 41 185 107V283C206 340 240 371 267 371C282 371 296 364 310 351C316 344 325 343 336 348C357 357 369 378 369 399C369 424 345 451 310 451C262 451 219 397 187 344H185Z" id="g58-112"></path></g><g transform="matrix(.013,0,0,-0.013,27.96,0)"><path d="M535 323V373H52V323H535ZM535 138V188H52V138H535Z" id="g117-34"></path></g><g transform="matrix(.013,0,0,-0.013,39.222,0)"><path d="M962 650H739L732 622L760 619C812 613 819 604 798 552C760 457 671 267 606 131H604L511 638H480L237 131H233L183 554C177 607 183 614 226 619L248 622L257 650H24L17 622C88 615 92 611 103 524L173 -11H203L450 491H453L543 -11H575L839 529C882 609 886 613 953 622L962 650Z" id="g113-88"></path></g><g transform="matrix(.0091,0,0,-0.0091,50,3.132)"><path d="M558 454L532 470C512 451 497 442 465 442C421 442 376 450 318 450C146 450 24 313 24 164C24 46 91 -12 183 -12C317 -12 439 105 439 247C439 306 428 346 382 385L383 389C414 384 450 379 485 379C517 379 539 412 558 454ZM357 273C357 191 313 28 205 28C149 28 111 79 111 160C111 266 175 396 280 396C298 396 328 386 341 357C353 331 357 315 357 273Z" id="g50-240"></path></g><g transform="matrix(.013,0,0,-0.013,55.759,0)"><path d="M962 650H739L732 622L760 619C812 613 819 604 798 552C760 457 671 267 606 131H604L511 638H480L237 131H233L183 554C177 607 183 614 226 619L248 622L257 650H24L17 622C88 615 92 611 103 524L173 -11H203L450 491H453L543 -11H575L839 529C882 609 886 613 953 622L962 650Z" id="g113-88"></path></g><g transform="matrix(.0091,0,0,-0.0091,66.536,3.132)"><path d="M525 275C525 381 464 451 380 451C338 451 289 439 241 405C158 347 127 277 106 152C51 -168 37 -216 24 -242L28 -257C42 -256 92 -247 117 -222C126 -213 134 -193 150 -69L166 32C184 10 211 -12 245 -12C276 -12 332 8 384 46C458 100 525 176 525 275ZM436 260C436 131 366 41 267 41C246 41 208 51 175 82C181 125 187 162 195 200C220 322 257 400 328 400C398 400 436 338 436 260Z" id="g50-239"></path></g></svg> is the attenuation function calculated using our approximate method.</div>

International Journal of Antennas and Propagation

fig6

Figure 6

Figure 6: A New Approximate Method for Lightning-Radiated ELF/VLF Ground Wave Propagation over Intermediate Ranges 