Designing of a multi-frequency vibrator antenna on meander line with resonant loads and fragmented “floating ground”

Abstract

Problem definition. Many VHF communication devices include multi-frequency vibrator antennas, among which a special place is occupied by the vibrator antennas with reactive loads as the most compact and simplest to produce. However, inductive loads usually used in practice don’t provide current cut-off at higher operating frequencies, which results in deformations of radiation patterns, and resonant circuits loads don’t provide sufficient shortening of the vibrator antenna due to appearance of shunt inductances. There is a need to formulate the new idea of the designing the multi-frequency vibrator antenna, which has absolutely another mechanism of work, is needed. Purpose. The purposes of this article are: to suggest the idea of the design the multi-frequency vibrator antennas, based on hybrid of meander line with parallel LC-circuits and fragmented “floating ground”; to form an equivalent scheme for calculating characteristics; to develop a methodology for calculating this type of antennas characteristics (input impedance, VSWR, current distributions over the vibrator and far-field radiation patterns); to do the calculation of characteristics of the monopole antenna on meander line with loads and to make an experimental check of the theoretical results. Results. A design of the multi-frequency vibrator antenna on meander line with parallel LC-circuits loads and fragmented “floating ground” is shown. An equivalent scheme for calculating antenna characteristics is given, an algorithm of calculation of input characteristics and current distributions over the antenna (both meander and “floating ground”) is described. The calculation of input impedance, VSWR, current distributions and radiation patterns of the vibrator antenna with two LC-circuits loads in meander line is done. An experimental check of the theoretical results in VSWR and far-field radiation patterns is made. Applicability of the proposed idea and methodology for the design the multi-frequency vibrator antennas on meander line is shown by analyzing calculated and experimental data. Practical significance. The results of this work can be used to design the multi-frequency VHF vibrator antennas with resonant loads, which have the identical radiation patterns at all operating frequencies.