Dual-band Butler matrix for WLAN systems

This paper shows the design of a dual-band Butler matrix aimed to cover the bands corresponding to the standards IEEE802.11a/b, with particular interest in WLAN systems, at the 2.4 GHz and 5 GHz bands. Measurements of the individual dual-band components which compose the Butler matrix are presented. Those components are: quadrature hybrid and 0 dB coupler. The phase shifter design is also described. A final design of the Butler matrix is proposed and measured. Over the proposed frequency range, the Butler matrix exhibits phase errors and couplings of within 13.5/spl deg/ and - 6.7 /spl plusmn/ 0.8 dB, respectively. A performance prediction of the Butler matrix connected to an array of isotropic and perfectly matched antennas separated half-wavelength in air is also briefly commentedPeer Reviewe

Dual-band planar quadrature hybrid with enhanced bandwidth response

This paper presents the theory, design procedure, and implementation of a dual-band planar quadrature hybrid with enhanced bandwidth. The topology of the circuit is a three-branch-line (3-BL) quadrature hybrid, which provides much larger flexibility to allocate the desired operating frequencies and necessary bandwidths than other previously published configurations. A performance comparison with other dual-band planar topologies is presented. Finally, a 3-BL quadrature hybrid for dual band (2.4 and 5 GHz) wireless local area network systems was fabricated, aimed to cover the bands corresponding to the standards IEEE802.11a/b. The measurements show a 16% and 18% bandwidth for the lower and upper frequency, respectively, satisfying and exceeding the bandwidth requirements for the above standards.Peer Reviewe

Optimization of linear multielement antennas for selection combining by means of a Butler matrix in different MIMO environments

An optimized linear multielement antenna (MEA) is presented for selection combining schemes that improves the selection diversity gain and selection diversity capacity in medium and low multipath environments, with respect to the performance achieved with a simple uniform linear array (ULA) using omnidirectional antennas, while it performs equally as well as a ULA in highly scattered environments. An analytical investigation based on the analysis of the correlation coefficients, together with simulations and extensive measurements, have been carried out for different fading multiple-input multiple-output environments ranging from line of sight (LOS) to non-LOS. Two MEAs are compared: a simple ULA with omnidirectional antennas and a MEA combining a ULA and a Butler matrix. The measurement results show that the nature of the proposed MEA is such that it is adaptive to any propagation scenario by simultaneously taking advantage of beamforming gain and signal diversity gain.Peer Reviewe

Dual-band Butler matrix for WLAN systems

This paper shows the design of a dual-band Butler matrix aimed to cover the bands corresponding to the standards IEEE802.11a/b, with particular interest in WLAN systems, at the 2.4 GHz and 5 GHz bands. Measurements of the individual dual-band components which compose the Butler matrix are presented. Those components are: quadrature hybrid and 0 dB coupler. The phase shifter design is also described. A final design of the Butler matrix is proposed and measured. Over the proposed frequency range, the Butler matrix exhibits phase errors and couplings of within 13.5/spl deg/ and - 6.7 /spl plusmn/ 0.8 dB, respectively. A performance prediction of the Butler matrix connected to an array of isotropic and perfectly matched antennas separated half-wavelength in air is also briefly commentedPeer Reviewe

Dual-band Butler matrix for WLAN systems

This paper shows the design of a dual-band Butler matrix aimed to cover the bands corresponding to the standards IEEE802.11a/b, with particular interest in WLAN systems, at the 2.4 GHz and 5 GHz bands. Measurements of the individual dual-band components which compose the Butler matrix are presented. Those components are: quadrature hybrid and 0 dB coupler. The phase shifter design is also described. A final design of the Butler matrix is proposed and measured. Over the proposed frequency range, the Butler matrix exhibits phase errors and couplings of within 13.5/spl deg/ and - 6.7 /spl plusmn/ 0.8 dB, respectively. A performance prediction of the Butler matrix connected to an array of isotropic and perfectly matched antennas separated half-wavelength in air is also briefly commentedPeer Reviewe

Optimization of linear multielement antennas for selection combining by means of a Butler matrix in different MIMO environments

An optimized linear multielement antenna (MEA) is presented for selection combining schemes that improves the selection diversity gain and selection diversity capacity in medium and low multipath environments, with respect to the performance achieved with a simple uniform linear array (ULA) using omnidirectional antennas, while it performs equally as well as a ULA in highly scattered environments. An analytical investigation based on the analysis of the correlation coefficients, together with simulations and extensive measurements, have been carried out for different fading multiple-input multiple-output environments ranging from line of sight (LOS) to non-LOS. Two MEAs are compared: a simple ULA with omnidirectional antennas and a MEA combining a ULA and a Butler matrix. The measurement results show that the nature of the proposed MEA is such that it is adaptive to any propagation scenario by simultaneously taking advantage of beamforming gain and signal diversity gain.Peer Reviewe