Radiation Pattern of a Vertical Dipole over Sea and Setup for Measuring thereof

Abstract

Original scientific paperIn this paper, a compact setup for measuring the radiation pattern of an arbitrary positioned antenna above the sea surface is presented. The antenna of interest was a vertical half-wave dipole. Due to impracticalities concerning the measurements using seaborne platforms, the setup was based around a shallow pool filled with actual sea water. The transmitting antenna-under-test (AUT) and the receiving antenna stands were placed on the solid ground, at the opposite sides of the pool, thus ensuring the stable platforms as well as the wave path over sea. The need for precise positioning of the receiving antenna along the circular path was avoided and the straight measurement line was used instead, yielding further simplification of the method. Both antennas were realized as printed half-wave dipoles. The measurements were carried out in ISM frequency band at 2.48 GHz. The chosen frequency enabled the realization of a compact setup for elevation radiation pattern measurements for AUT heights up to 2λ above the sea surface. The measurement results were compared to the theoretical and simulation results for a half-wave dipole over sea, showing a good agreement. Detailed evaluation of the measurement uncertainty was undertaken, indicating the critical points in the realized setup.Key words: Antenna above sea surface, Lossy dielectric ground plane, Radiation pattern measurement setup, Vertical half-wave dipole Dijagram zračenja vertikalnog dipola iznad mora i mjerni postav za njegovo mjerenje. U ovom radu predstavljen je kompaktni postav za mjerenje dijagrama zračenja proizvoljno postavljene antene iznad površine mora. Predmet analize je vertikalni poluvalni dipol. S obzirom na nepraktičnost mjerenja na plovećoj platformi, postav se temelji na plitkom bazenu napunjenom stvarnom morskom vodom. Stativi za ispitivanu odašiljačku antenu i prijamnu antenu postavljeni su načvrstom tlu na nasuprotnim stranama bazena, tako da se antene nalaze na stabilnim platformama, a putanja vala se nalazi u potpunosti iznad mora. Dodatna značajka predložene metode jest pravocrtno pomicanje prijamne antene tijekom mjerenja dijagrama zračenja. Time je izbjegnuta potreba preciznog pozicioniranja po kružnoj putanji, što je dovelo do dodatnog pojednostavnjenja metode. Obje antene izraîene su kao poluvalni dipoli u planarnoj tehnologiji. Mjerenja su provedena na ISM frekvenciji od 2.48 GHz. Odabrana frekvencija omogućuje izradu kompaktnog postava za mjerenje vertikalnog dijagrama zračenja za visine odašiljačke antene do 2λ iznad morske površine. Mjerni rezultati pokazuju dobro slaganje s analitičkim rezultatima i rezultatima simulacije za poluvalni dipol iznad mora. Provedena je i prikazana detaljna procjena mjerne nesigurnosti, kao pokazatelj kritičnih točaka u realiziranom postavu.Ključne riječi: antena iznad mora, dielektrik s gubicima, uzemljena ravnina, mjerni postav za mjerenje dijagrama zračenja, vertikalni poluvalni dipol

Human Exposure to Field Radiated by Vertical Dipole Antenna over a Lossy Half-Space using Analytical Approach

“…Thin wire radiation above a lossy half space was originally introduced by Sommerfeld in 1908 [3] and has been the subject of interest of many researches [3][4][5][6][7][8][9], mainly because of many applications, such as wireless telecommunications [7,10], bioelectromagnetic, or surface wave propagation [11]. Moreover, small and directional antennas are used in 5G networks [12].…”

“…Approximation which enables analytical solution of the field integrals as well as numerical approach uses Fresnel Reflection Coefficients Method (RCM). The use of RCM is related to the first term in the asymptotic expansion of the Sommerfeld integrals, which saves considerable computational time [5].…”