DESIGN OF A TWO-BAND PLANAR YAGI ANTENNA

Abstract

Modern development of antenna and microwave devices takes place is closely interconnected with many fields of science and techniques. Antennas are most important functional components of different radioengineering systems. The complication of radio electronic apparatus applied in communication systems and its requirement of miniaturization  lead to the problem of decreasing the antenna sizes.  In that respect, antennas made by the technology of printed circuit boards are more perspective and find wide application owing to their numerous advantages: thin profile, small mass, easy preparation opportunity, integration in a microwave circuit.  A typical structure of printed circuit board antennas is a dielectric layer placed on the conductor.

 Two structures of printed yagi antennas are presented: a single-band, and created by it a two-band antenna. The mentioned antennae are modelled and the calculation of their characteristics are carried out by using one of the most powerful modern programs of electrodynamic simulation, the FEKO, which represents a new approach to the design of three-dimensional microwave devices.

 A two-band printed Yagi antenna is developed. As an active element for the given antenna, the antipodal Vivaldi structure is developed. The antipodal Vivaldi structure is described. The phase center of the two-band printed Yagi antenna active element is determined. Passive elements are placed towards the phase centre.

 The single-band and two-band antenna calculation results are presented in the form of graphs. The patterns of the mentioned antennas in the E and H planes in the polar form are presented. The value of the main lobe of the pattern at half power is calculated. The frequency dependences of the voltage standing wave ratio (VSWR), and the gain of these antennas in the operating frequency range 2.04…2.47GHz and 5.13…6.32 GHz are presented.