Pekka Salonen

Single-feed dual-band planar inverted-F antenna with U-shaped slot

The development of small integrated antennas plays a significant role in the progress of rapidly expanding wireless communication applications. This paper describes a novel dual-band planar inverted-F antenna (PIFA) for wireless local area network applications. The proposed PIFA uses single feed only. A novel top-plate geometry, a U-shaped slot, is discussed. An example is given for this novel slot shape for frequency bands of 2.4 and 5.2 GHz. Simulation based upon the method of moments (MoM) is used to model the performance of the antenna. Comparisons with results measured on fabricated antenna structures are provided for simulations validation.

A novel fabric WLAN antenna for wearable applications

The development of wearable computer systems and smart clothing has been rapid. They are coming more and more lightweight and quite soon we will see a wide range of unobtrusive wearable and ubiquitous computing equipment integrated to into our everyday wear. Rapid progress in wireless communication promises to replace wired-communication networks in the near future in which antennas have a more important role. This paper presents a novel fabric WLAN antenna for wearable applications such as sports wear and emergency worker outfits. The substrate of the patch antenna is made of a very low-cost fleece fabric. The radiating element and groundplane are made of knitted copper. To our best knowledge this is the first compact fabric antenna design for commercial smart clothing. Measured results are compared with simulations and good agreement was observed.

A small planar inverted-F antenna for wearable applications

Small printed antennas will replace the commonly used normal-mode helical antennas of mobile handsets and systems in the future. This paper presents a novel small planar inverted-F antenna (PIFA) which is a common PIFA in which a U-shaped slot is etched to form a dual band operation for wearable and ubiquitous computing equipment. Health issues are considered in selecting suitable antenna topology and the placement of the antenna. Various applications are presented while the paper mainly discusses about the GSM applications.

A 2.45 GHz digital beam-forming antenna for RFID reader

Spatial filtering using adaptive or smart antennas has emerged as a promising technique to improve the performance of cellular mobile systems. Due to the digital nature of the control of spatial filtering a quantization error is readily present. This is due to the fact that weights and phase information is provided with the aid of finite wordlength processors. This paper presents the development of a five-element digital beam-forming antenna for RFID (radio frequency identification) reader operating on the 2.4 GHz ISM-band. The paper presents a detailed description of the operation of beam-form control including the analysis of 4-bit phase shifters. In addition, the result shows that the quantization error, even if it small, can degrade the pattern so dramatically making it unacceptable. However, we show that with as low number of control bits as four the desired radiation characteristics can be achieved.

A novel Bluetooth antenna on flexible substrate for smart clothing

The development of wearable computer systems and smart clothing has been rapid. They are becoming more and more lightweight and soon we should see a wide range of unobtrusive wearable and ubiquitous computing equipment integrated into everyday wear. Rapid progress in wireless communication promises to replace wired-communication networks, in which antennas play a more important role. This paper presents an antenna design for wearable applications. Due to wearable system demands this paper discusses mainly physically small planar antennas. A design example is given in which a flexible PIFA (FlexPIFA) structure for single and dual-band operation is introduced into smart clothing in Bluetooth and UMTS fields. To our knowledge this is first time a thin and flexible antenna has been designed for commercial smart clothing. Measured results are compared with simulations and good agreement was observed. In addition the effect of the human body on antenna performance is discussed.

Planar rectennas for 2.45 GHz wireless power transfer

Three planar rectennas (rectifying antennas) on different PCB materials have been designed. Patch antennas were designed with a MoM (method of moments)-based simulator while in RF-to-DC conversion circuits microstrip and discrete rectifier diode models were utilized in circuit simulations. The goal was to achieve maximum antenna and conversion efficiency at the desired reception power level. 80% antenna efficiency and 70% conversion efficiency was achieved in simulations. The terms for achieving a sufficient reception power level were considered and compared to the performance of the designed antennas. The accuracy requirements for the realization of these rectenna structures were also defined with the aid of both simulation and measurement results.

Exposing textile antennas for harsh environment

Textile antennas as part of soldiers garment is commonly exposed to various harsh operational conditions. It is crucial that the communication link between soldiers is not compromised by the environmental conditions. The effect of water, ice and snow on the performance of fully textile antenna is studied in this paper. The effects of environmental exposure on antenna performance is validated via experimental tests, using a satellite communication systems; Iridium for a bi-directional satellite data transmission and GPS for a reception tests. During the tests the antenna is immersed into water, exposed to ice and snow while the communication link remains active. These results show that thorough understanding of the textile antenna design process leads to an optimal antenna performance even under the harsh environmental conditions.

Textile material characterization for SoftWear antennas

Modern industrial textile materials are composed of mechanically strong fibers that find their applications in integrated antennas within soldiers garment and armors in ballistic protection as well. This paper will cover electromagnetic characterization of such textile materials for SoftWear antenna substrate. Dielectric permittivity and loss tangent are analyzed and measured in varying relative humidity and temperature. In addition, the application of conductive textile materials to antennas is analyzed and discussed thoroughly.

An intelligent 2.45 GHz beam-scanning array for modern RFID reader

As part of the general identification procedure, radiofrequency identification (RFID) is an essential field of research in the modern industrial automation. Radio frequency identification is among the most technically advanced methods of collecting data automatically. This paper presents an intelligent 2.45 GHz beam-scanning array for a RFID reader. The design is based on the paper industrys needs but is still applicable to other fields of industry. A new current amplitude distribution is applied to feed the array elements. With this amplitude current distribution the -37.5 dB sidelobe level is achieved while maintaining the half power beamwidth at the same level as the Dolph-Chebyshev current amplitude distribution with a sidelobe level of -30 dB. Thus, the new distribution is a compromise of binomial and Dolph-Chebyshev. The system level description of the intelligent beam-scanning array is also discussed.

Textile antennas: Effect of antenna bending on radiation pattern and efficiency

In this paper the radiation characteristics of three different textile antennas, namely, a conventional patch antenna, a dual-band antenna, and an EBG antenna is focused. The results show that antenna bending has remarkable effect on radiation characteristics, i.e., radiation pattern shape, gain, and radiation efficiency. It is intuitively clear that antenna bending broaden the radiation pattern in the bending plane, which results a drop of gain. In addition, it was also noticed that radiation efficiency slightly reduces due to the antenna bending. These results again show that EBG antenna performs better compared to the conventional antenna.