P. Le Thuc

Dual-Band WLAN Diversity Antenna System With High Port-to-Port Isolation

In this letter, an innovative technique is proposed to enhance the port-to-port isolation of two closely spaced dual-band radiating elements in the WLAN 2.4-2.5-GHz and 5.15-5.825-GHz frequency bands. This broadband technique consists in inserting an optimized parasitic element between the two antennas of a multiple-input-multiple-output (MIMO) set-top box. High port-to-port isolation is obtained, and the computation of the diversity performance shows suitability for enhanced diversity and MIMO applications.

Enhanced diversity antennas for UMTS handsets

In this paper, we present several UMTS multi-antenna systems having radiators with low mutual coupling and high total efficiency. Firstly, two antennas are simply positioned at the top of a small ground plane whose size is representative of the Printed Circuit Board (PCB) of a mobile phone. A solution is then proposed to decrease their mutual coupling and enhance their total efficiency. Then the same neutralization technique is applied to a four-antenna structure. These systems are fabricated and measured. The simulated and measured S-parameters and total efficiencies are presented. The envelope correlation values are also shown and discussed. It is demonstrated that this neutralization technique could be easily implemented at the terminal side of a wireless link to achieve enhanced diversity antennas.

MIMO performance of enhanced UMTS four-antenna structures for mobile phones in the presence of the user’s head

In this paper, we have presented the reverberation chambers (RC) evaluation of the multiple-input-multiple-output (MIMO) system performance of several UMTS four-antenna systems with low and high planar inverted-F antennas (PIFAs) isolation. It has been measured that the neutralization technique is always improving the performances even with the presence of the users head, due to the high isolation obtained between the antennas and their high total efficiencies.

Evaluation of the performances of several four-antenna systems in a reverberation chamber

This paper results from a short-term mission granted by the COST 284 where the antenna-design competences of the LEAT have been gathered with the measurement skills of Chalmers Institute of Technology. Three multi-antenna prototypes have been characterized in the Bluetest reverberation chamber in terms of total efficiency and diversity gain. Particularly the performances of an initial four-antenna system with poor isolation have been evaluated with and without the presence of a phantom head and then we characterized in the same manner two prototypes with highly decoupled antennas. The paper especially focused on demonstrating that the neutralization technique is still giving improvements in the presence of the users head.

Diversity characterization of optimized two-antenna systems for UMTS handsets

This paper presents the evaluation of the diversity performance of several two-antenna systems for UMTS terminals. All the measurements are done in a reverberation chamber and in a Wheeler cap setup. First, a two-antenna system having poor isolation between its radiators is measured. Then, the performance of this structure is compared with two optimized structures having high isolation and high total efficiency, thanks to the implementation of a neutralization technique between the radiating elements. The key diversity parameters of all these systems are discussed, that is, the total efficiency of the antenna, the envelope correlation coefficient, the diversity gains, the mean effective gain (MEG), and the MEG ratio. The comparison of all these results is especially showing the benefit brought back by the neutralization technique.

User’s head and hand influence on the diversity performance of neutralized two-antenna systems for UMTS handsets

In this paper, we presented the influence of the userpsilas head and hand on the diversity performance of 0.1 lambda0 spaced PIFAs for UMTS handsets. If the DSG of the PIFAs of the handset positioned in free space is found to be very high (more than 8.5 dB), the DSG is severely degraded in the presence of the user. However, it seems that there is still an interest to add a second antenna for diversity purpose as the DSGs are around 3 dB in the UMTS Rx band. Further results with even more closely spaced PIFAs (down to 0.03 lambda0) will be presented at the conference.

Human implanted spiral antenna for a 2.45GHz wireless temperature and pressure SAW sensor system

In this paper, we presented a new technique to optimize a human implanted spiral antenna for a 2.45 GHz wireless temperature and pressure SAW sensor system. The antenna was designed to especially operate when closely implanted to a human heart. In a homogenous phantom, we have shown that it was possible to simply link the two arms of a traditional dipole to achieve better matching and reduced antennapsilas dimensions.

Miniature circularly polarized antenna for SAW sensor measurements

A novel miniature antenna for a wireless pressure measurement system based on a passive Surface-Acoustic-Wave (SAW) sensor is presented in this paper. The SAW sensor used for this application works at 434MHz in the Industrial-Scientific-Medical (ISM) band. The miniature antenna (λ/12 × λ/17 × λ/63) [6 × 4 × 1.2cm3] consists of a Planar Inverted F Antenna with a spiral slot. The antenna presents a radiation efficiency of 50%, a bandwidth of 1.75MHz (0.4%) and a left hand circular polarization (LHCP). The SAW sensor as well as the antenna design and the association of both elements are exposed.

Optimization of the neutralization technique to enhance the diversity performance of a two-antenna system for UMTS mobile phones

In this paper, we have shown that it was still possible to get a very good diversity system gain for very closely spaced UMTS PIFAs (0.027 lambda0) positioned on the PCB of a small communicating object by using the neutralization technique. The goal is to see how efficient can be the neutralization technique when the radiators are separated by a very small distance or in other terms, how close can be placed two small UMTS PIFAs on a small ground plane while still having a satisfactory DSG with our neutralization technique. Several measurements will be soon conducted in the Bluetest reverberation chamber of Chalmers Institute to confirm these values.

Small meandered PIFA associated with SAW passive sensor for monitoring inner temperature of a car exhaust header

Wireless sensors based on passive Surface Acoustic Wave (SAW) technology serve to accurately determine physical quantities in harsh environments. In this paper, we present a meandered Planar Inverted-F Antenna (PIFA) with a small ground plane designed to be associated with a SAW sensor to monitor the inner temperature of a car exhaust header. The SAW sensor, the design of the antenna, the association of both elements and some wireless interrogation results are presented.