arXiv subjects

Mikko Karkkainen

Publications and source records attributed to Mikko Karkkainen.

2 recordsLinked to original sources

arXiv2005

Improving antenna near-field pattern by use of artificial impedance screens

An antenna prototype utilizing artificial impedance surfaces to control the near field distribution is described. The antenna is a folded dipole placed above a finite-size artificial impedance surface. We have found that the field screening is most effective if the surface is a metal conductor. However, to achieve a reasonable value of the radiation resistance the dipole should be located far off the screen. If the surface is a magnetic wall, the antenna design is more compact, but the field behind the screen is large. Here we realize a compromise solution using an inductive surface of a moderate surface impedance, which allows realization of an effective near-field screen with still a reasonably low-profile design.

physics.class-ph↗

arXiv2005

Light-Weight Base Station Antenna with Artificial Wire Medium Lens

In this paper we study the possibility of utilizing a loaded wire medium as an artificial material for beam shaping element in base station antenna applications. The wires in the lattice are loaded with a proper capacitive impedance to come up with a structure effectively operating as a dielectric lens at the UMTS (Universal Mobile Telecommunications System) frequency range. It is proven with full-wave simulations that the interpretation of a finite size wire lattice as a dielectric lens is physically sound even with a moderate number of lattice periods. A prototype having a mechanically reconfigurable beam width is constructed and measured. It is shown that very promising performance can be achieved with a rather simple structure and a cheap manufacturing process.

physics.class-ph↗