A study on the effect of building on the HF direction finding
The effect of new building on the high-frequency (HF) direction finding (DF) is analyzed. Commercially available software is used to get array manifold of the HF DF system taking the effect of the new building into account. The terrain, building and the array antenna system are modeled. The new building near the antenna system is also modeled to see whether it actually has an effect on the performance of the DF system. Interferometer DF algorithms has been employed.
The Effect of Ground Reflections and Scattering on an Interferometer Direction Finder
The azimuth and elevation angles of an airborne beacon transmitter can be determined using a direction finder comprised of two orthogonal interferometers located near the earth's surface. In this paper we consider the reflection of the incident electromagnetic field by the earth's surface and the resultant effect on the direction-finding system. The analysis yields an upper bound or limit to the interferometer phase error and the corresponding error in bearing angle that can result because of specular reflection and diffuse scattering.
Rigorous analysis of probe-fed printed annular ring antennas
This paper presents calculated and measured results for the input impedance and radiation performance of probe-fed printed annular ring antennas. Geometries featuring stacked rings as well as shorting posts are considered. A numerical model is presented that is based on a full-wave spectral-domain moment-method solution. In this solution, a specialized attachment mode-expansion function is used to model the connection between the probe feed and the printed ring. Measured results are presented and compare well with the theory. Annular rings are found to have certain advantages over circular and rectangular microstrip antennas.