Near-field to far-field transformation applied to UHF antennas over lossy ground

Abstract

This paper deals with a near-field to far-field transformation able to predict the radiation of UHF antennas located over a lossy ground. From in-situ near-field measurements, an equivalent set of dipole sources is obtained as a model of the characterized antenna. The paper details the main steps of the transformation and describes the specific experimental set-up designed for the application. Simple directional antennas (monopoles array) as well as more complex omnidirectional antennas (like a biconical antenna as a scaled-down model of a HF antenna) have been tested in realistic environments. This approach is very efficient for separating the contributions of the radiated waves: the sky wave and the surface wave.

Design of multi-band and high radiation intensity piezoelectric antenna based on external circuit

“…Figure 5(a) shows the electric field distribution of the near field of the piezoelectric antenna simulated by COMSOL, and Fig. 5(b) shows the electric field distribution of the far field of the piezoelectric antenna obtained by using the near-far field transformation theory [26]. From the electric field distribution of the near-field and far-field of the original piezoelectric antenna in Fig.…”

SimROS: a simulator for the design of HF surface wave radar - Application to maritime target detection

“…The modelling of the antennas in SimROS is performed through a model of the radiating structures obtained by means of a set of equivalent dipoles stored in a library [2]. This choice allows to pre-process the complete modelling of the antenna with its environment (beach, cliff...) outside the code in order to not degrade the computation time.…”

Simulations on the effects of an optimized bowtie dipole antenna with an adaptive FIR filter

“…Some TV channels make use of frequencies in the ultra high frequency (UHF) range, cellphones make use of frequencies in the UHF range as well, and radar makes use of frequencies in the UHF range too [3]- [5]. The UHF range has a variety of purposes [6] and radio makes use of frequencies in either the low frequency (LF), medium frequency (MF), or high frequency (HF) range for shortwave, AM radio, FM radio [7]. One of the most common types of antennas used for signal propagation and reception is the dipole antenna.…”