The Electric Field at the Ground Plane Near a Top-Loaded Monopole Antenna with Special Regard to Electrically Small L- and T-Antennas

The present a rt icle deals with t he calculation of t he electric field strength at t h e ground p lane near electrically small top-loaded a ntenn as having a known current distribution, with s pecial reference to Land T-a ntennas . The formulas a nd numerical values obtained here fo), t his component may be used in calculating t he contribu t ion to t he ground losses around a n a ntenna of t he above-mentioned type due to t he vertical component of t he eart h clll'rent. An exact ex pression involving an integral has been obta ined for the electri c field strength at the ground plane due to t he current in a linear an te nn a having an ar bitrary inclination . If the length a nd t he height of the a ntenna is small compared to the wavelength, and if t he current distribu t ion on the a nten na can be expressed by a fini te number of te rms of a power series, it is t heoretically poss ible to obtain a closed exp ress ion for t he fi eld at t he ground plane. H owever, only in special cases does t his expression become sufficiently simple to be of practical value for n umeri cal calculations. 'Working formula have bcen obta ined a nd numeri cal calculations carried out for t hE' n ear zone fi eld of an electrically small ver t ic!) l or hori zo ntal a nte nna with a linea r current d istribu tion. Based on t heSe res ult, a calculation has been made of the electri c fi cld s t rength at the ground plane near electri cally small La nd T-antenn as. Also the re lative eontribut io ll to thIS component due to th e top loading has been calculated.