""\ \ A Mixed-Path Groundwave Field-Strength Prediction Virtual Tool for Digital Radio Broadcast Systems in Medium and Short Wave Bands Levent Sevgi D ni versi, Electronics and Communication Engineering Department Zeamet Sok. è 2 AClbadem/Kadlkoy, 2 I stanu l , Turkey E-mail: Isevgi@dogus.edu.tr Abstract The emerging digital technologies for the communication bands from LF up to VHF - bands traditionally used by analog radio systems - necessitate reVisiting early analtical propagation methods, and urge engineers to develop novel propagation prediction tools. Eit analtical propagati on techniques are based on ray-mode approaches d the Millington curve-fitting approach for mixed-path p ropagation. These have been endorsed and are used  related I (formerly, CCIR) Recommendations. These techniques are sssd, i ch ar a teristic examples produced via a newly introduced MF/HF groundwave propagation prediction vitual tool (GPV). Kewords: Broadcasting; land mobile radio ellular systems; digital audio broadcasting; dig i tal radio; electromagnetic propagation; electromagnetic scatering; electromagnetic surface ;ro wave propagation; HF rdoro paio; radio propagation; ray tracing; mode matching methods; ray-mode approximations; hybrid methods; analytical techniques; numerical analysis; suface impedance modeli ng 1. Introduction G rod-wa propagation has long b oe othe iport opions foredium- and log-range cunicaton.  addi tio to the classical H broadcast and communication sys tems, erging  a H adar tehnologes [, 2] nd nteli gent tansportation systems [3] require understanding opropaga ton characteritic oer e Þh's suae alonƦeaistic poa gat i on paths. Digital adio odile (DM) i s oe othese new telges ,] for hortwae to long-wave systms,endorsed y inttnal standrs organizations such as   and é Some applications nclde 255-28. Hz aeronautical broadat system, 283.-31K karitebeaons, 405-415 adio  (direction ndng), 615-526.U Hz maritime radio tle graphy, et. e oectie ot his tutorial is to revisit propagation-predic tion ehods based on anlytal approaces , toether it har aceristc eample, inludin mulple id-ath popagation senais, produced wth a newly inrodued, user-riendly groundwave propagationirtal too() [_. The Millington  can e donloaded om http:// ww3.dogus.edu.trllsev gi. e ed-srength pedion or digital sond roadcasting systes is vredby-ecomendation-132! [6] and  EEEaaa ë  ê 06 161 [7], and pints out thsagofemendation -368- 8] for he oundave ield-strength prediction n te M band. Recommendation P-36- fuly coers both m and d grondae-propaaton prolem. It gves a set o curves or prdctd el strength asa con ofdite o ver tcaly poariedae n th Mï and  ands or variet ol ues of groundcondutvty, a, and relative permittivity,  . ese cues are valid for a certai range o antenna heights, u   = 1.2a1/2 . 3 / 2   60,1., and for non-a oiudnal pahs with obstacles not higher than a wavelenh (,.) nd not lose to either the transmitter or t receivr tha n 0 m. A irtual ol f or realistic propagaion suation st incude all eevant satring omponen (.g., multip reec tins  reractions, edge!tip difractions, surf ace and/o lay waves, tc.) that acounto he path loss beteen ay twopoins in a three-densonal (3Í) d i gi tal l parameterized enonment. In prviou plictions [9-11], available anaytic models or ground-wave propagation were listed in hronologca order, and the dealied conditons under whih th appy ere dissed. ºmong them, pecil attention was given to the (ray-optical) pls (surface-wave) model oorto 12], and to t surfac-gided mode mode oait [13. he poblemhas also been discsedn [@, which rפnœ a nic t and nt  ide-ranin survey of radowae propagation an atnna modeling.  eld regth predic ion algoritn was designed [9] to dynmialy home in on the est hyridaion the orton and ait analytic SS22$22EEE 