R. Serrano

RFID-based flexible low-cost EM field probe

The capability of the RFID tags as a low cost flexible device to measure the EM complex field distribution has been presented and some preliminary results presented. The devices do not need any kind of electrical connexion giving them a high versatility to act as a remote EM probing device under different conditions of positioning and accessibility. Sensitivity and dynamic range are aspects that need to be further investigated in order to have systems capable of exploring large areas in terms of spatial dimensions and amplitude levels.

Activities on terminal antennas in ACE2

This paper presents the work carried out in the ACE Network of Excellence regarding small antennas. Three aspects are covered in three projects : Small antenna technologies, small terminal antenna technologies and benchmarking of small terminal antennas measurement facilities. The aim is to identify the newest trends in antenna design and measurement for personal communications devices, and suggest novel solutions and design methodologies for various applications.

Active balanced feeding for compact wideband antennas

This paper demonstrates the advantages of using active devices, which have balanced complex impedance, for feeding wideband antennas. Some techniques to simultaneously increase the frequency bandwidth and reduce antenna dimensions are also discussed.

Small antenna fundamentals and technologies: Future trends

This paper is an overview of the on-going research work carried out at the Antenna Centre of Excellence regarding small antenna technologies. After a review of the state of the art in the area of small antennas and their fundamentals, growing technologies are identified. When dealing with advanced systems, the actual analytical modeling techniques, basically formulated for a single port quasi-resonant stand-alone antenna are not completely valid anymore. A deep approach to the requirements, modeling and design techniques for the future small antennas must be carried out, which implies a special research effort.

Miniature Antenna as Optimal Load for High Efficiency Integrated Active UHF Microsystems

This paper describes an electrically small active antenna optimized to deliver the maximum power within 800-1000 MHz band, being implemented in CMOS technology. The antenna plays the roll of an optimum load for the active device (PA), minimizing the total size and improving the system performance. The proposed antenna as a stand-alone element, with dimensions of lambda0/15timeslambda0/15timeslambda 0/200, reaches efficiency values of 50% and bandwidth 14.5 MHz. Experimental results for the active element (PA) show a power-added efficiency (PAE) close to 30%. The PAE for the active antenna is measured by combining the calorimetric method with the measurement of the received power

Evaluation of two novel non-invasive measurement methods for small antennas

This paper evaluates two non-invasive measurement methods for the characterization of electrically small antennas: the backscattering technique and the calorimetric method. The radiation efficiency of a small patch antenna of dimensions ¿0/15 × ¿0/15 and thickness ¿0/250 has been measured with both techniques and compared with Wheeler cap method.

Port balance, efficiency and correlation impact evaluation for MIMO compact multiantenna systems

The diversity gain and efficiency of two multiantenna prototypes have been evaluated with the reverberation chamber, which represents an advantageous measurement method due to its low time consumption and its high accuracy. The relation between port balance, efficiency, correlation and diversity gain has been analysed for the two compact multiantenna prototypes: Q-dime and 4-square, following a procedure according to Figure 1. Taking into account the good behaviour of both antennas regarding correlation (rho lower than 0.1), it can be said that the apparent DG difference of 0.8 dB between both prototypes is due to the amplitude unbalanced ports: since there is a branch much worse than the other three in case of 4-square patch, only the 3 good elements will be used in the selection combining, becoming a 3times3 system. The effective DG difference between the two structures is approximately 2 dB of which 0.8 dB is due the contribution of the port unbalance. The additional 1.2 dB increase is caused by the higher losses in the antenna elements, which is in accordance with the efficiency measurements.

Miniature multiantenna for optimal capacity in wireless microsystems

Next generation of wireless communications will require systems with broadband capabilities in small robust antennas. Compact multiple-input multiple-output (MIMO) antenna is a suitable candidate for fulfilling mobile applications demands for high speed and high quality transmission. In this paper, a miniature multi-layered broadband four-element antenna with an optimized decoupling technique is presented. The antenna structure, which has been implemented in a reduced area of lambda/2timeslambda/2, operates at the wireless frequency band of 2.45 GHz. Each of the four radiating elements consists of two stacked patches over a ground plane. Four decoupling bridges have been placed between those elements in order to decrease mutual coupling and maximizing the capacity for a complete RF system channel model.