L. Freytag

Omnidirectional dielectric electromagnetic band gap antenna for base station of wireless network

Base stations need omnidirectional antennas with high gain and small size. The authors present an electromagnetic band gap (EBG) antenna which has an omnidirectional pattern in the azimuth plane and a low beamwidth in the elevation plane. This antenna, called a coaxial EBG antenna, works at 5.8 GHz and has been designed to have a gain equal to 9 dB. A study of this antenna with two types of excitation, that is to say with a wire-patch antenna and with two planar dipoles, has shown that the results in terms of gain and bandwidth are equivalent. Nevertheless, a certain advantage is given to the excitation by two planar dipoles in terms of side lobes. On the contrary, the wire-patch antenna gives a better omnidirectionality.

Cosecant-squared pattern antenna for base station at 40 GHz

We present a very small and very low cost antenna which realizes a cosecant-squared pattern. This base station antenna has been developed within the framework of the European project BROADWAN (Broadband services for everyone over fixed Wireless Access Networks). The antenna has been designed to work at 41 GHz, the frequency of the LMDS system. It permits us to resolve a problem of wireless links, that is the presence of a power gap in the area near the base station. This antenna is an array of eight printed patches with different weightings to form the desired diagram. The amplitude and phase distribution produces the best pattern with a maximum of gain (15 dB).

Design of a Cosecant-Squared Pattern Antenna Fed by a New Butler Matrix Topology for Base Station at 42 GHz

The purpose of this letter is to offer new performance characteristics to base station antennas. The proposed antenna is developed for the European project BROADWAN framework. We propose a new switched beam antenna array based on the 5 times 8 novel Butler matrix topology which provides a cosecant squared elevation pattern. In this letter, the implementation of the beamforming network and the cosecant squared feed lines at 42 GHz are detailed and a comparison between simulated and experimental results is presented.

New development around omnidirectional electromagnetic band gap antennas

The omnidirectional electromagnetic band gap (EBG) antenna has already been presented (Freytag, L. et al., 2004 URSI EMTS Int. Symposium on EM Theory, vol.1, p.600, 2004; 2004 IEEE AP-S Int. Symp. vol.1, p.815, 2004). It is composed of a metallic center core surrounded by concentric dielectric tubes. The performance of this new type of EBG antenna is very interesting, with high gain and low side lobes. The gain variations in the azimuth plane are also very low. This antenna is suited to base stations of wireless networks in order to cover large cells with only one antenna. The paper presents the performance that can be obtained with this type of antenna in terms of gain and radiation bandwidth versus EBG materials used. We also give a method to improve the performance; the results obtained with a prototype are presented.

Multilayer switched beam antenna with cosecant-squared elevation pattern for communication systems

The purpose of this paper is to offer new performances to the base station antennas. We propose a new switched beam antenna array based on the 5 times 8 novel Butler matrix topology and providing a cosecant squared elevation pattern. In this paper, the implementation of the beamforming network and the cosecant squared feeding lines at 42 GHz are detailed and some results are presented. The antenna has been fabricated to validate our simulations and the measure process is in progress.

Dielectric and metallic Electromagnetic Band Gap antennas for omnidirectional coverage of telecommunication networks

This paper presents omnidirectional metallic EBG (Electromagnetic Band Gap) antennas. The composition of the structure is explained and some typical radiation patterns in the principal planes of the antenna are shown. The performances of the antenna in terms of directivity and radiation bandwidth are defined function of the EBG material composition and of the height of the antenna. Finally, a comparison between dielectric and metallic EBG antennas is presented in order to bring to the fore the advantages of metallic structures.