I.T.E. Elfergani

Linear and nonlinear crosstalk in MIMO OFDM transceivers

This paper studies the effect of nonlinear and linear crosstalk in a MIMO (multiple in, multiple out) transceiver. These effects are mainly due to the power amplifier (PA) nonlinear behaviour and mutual coupling of antennas in the MIMO transmitter. The effects of the crosstalk interference on the signal performance are studied based on the measured error vector magnitude (EVM) at the transmitting antennas. The simulation and measurement results show that PA nonlinearity and RF crosstalk need to be considered in the design process.

Compact microstrip antenna design for microwave imaging

An ultra-wideband microstrip antenna design is considered with respect to applications in breast cancer detection. The underlying design concept is based on ground penetrating radar (GPR). Simulated and measured prototype performance show excellent performance in the input impedance and radiation pattern over the target range from 4 GHz to 8 GHz. The 4 GHz to 8GHz frequency band for microwave imaging perform better in comparison with other microwave frequencies. The antenna also shows a reasonable uniform radiation performance in the broadside direction which contributes to the reduction of clutter levels, thus aiding the reconstruction quality of the final image

A Frequency Tunable PIFA Design for Handset Applications.

A frequency tunable planar inverted F antenna (PIFA) is presented for use in the following bands: DCS, PCS, and UMTS. Initially, the tuning was achieved by placing a lumped capacitor, with values in the range of 1.5 to 4 pF, along the slot of the radiator. The final tuning circuit uses a varactor diode, and discrete lumped elements are fully integrated with the antenna. The antenna prototype is tunable over from 1850 MHz to 2200 MHz, with an associated volume of 21×13.5×5 mm3, making it suitable for potential integration in a commercial handset or mobile user terminal.

A novel dual band tunable balanced handset antenna for WLAN application

This paper presents a tunable balanced antenna covering WLAN frequency bands near 2.4 GHz (2.4–2.4835 GHz) and 5 GHz (5.15–5.35 GHz & 5.650–5.925 GHz), for mobile application. The design is based on loading two variable capacitors onto the planar balanced antenna to electronically tune its resonant frequency; the higher frequency was tuned with the capacitance varying from 0.1pf to 0.3pf, while the lower frequency band remains constant. Performance of the proposed antenna was analyzed and optimized against the two targeted frequency bands. For validation, the antenna prototype was fabricated and tested then the measured results were compared to simulation ones. The performance of this proposed antenna was verified and characterized in terms of the antenna reflection coefficient |S11|, radiation pattern and power gain.

A Compact UWB Antenna Design for Breast Cancer Detection

Near fleld imaging using microwave in medical applications has gain much attention recently as various researchers show its high ability and accuracy in illuminating object compares to well known screening tools. This paper documents the development of new compact ultra wide bandwidth antenna designed primarily for microwave imaging application such as breast cancer detection. A parametric study is carried out using two well known softwares packages to achieve optimum antenna performances. The performance of the Prototype antenna is tested and analyzed experimentally and exhibit reasonable agreement with the simulations.

Tunable RF MEMS Bandpass Filter with Coupled Transmission Lines

Passive and active devices are essential devices in mobile and base stations’ transceiver. Consequently, these devices dominated the large part of the PCB of the today’s transceiver. However, the tomorrow’s mobile terminals without circuit tunability would be extremely large in size to accommodate present and future radio access technologies (RATs). The stand-alone transceiver for one single RAT is comprised of single passive and active devices and adding two or more RATs for the same transceiver would require adding two or more devices, since all of these RATs standards work on different frequency bands. Apparently, without tunability approach, this will increase the complexity of the system design and will cover a large part of the circuit space leading to power consumptions, loss which results to the poor efficiency of the transceiver. In this work, a miniaturized RF MEMS tunable bandpass is developed to operate in the frequency range from 1.8 to 2.6 GHz.

A compact size reconfigurable PIFA antenna for use in mobile handset

A planar inverted-F type reconfigurable antenna with slot is presented. The antenna can cover frequency bands which include Digital Cellular Service (DCS: 1710–1880 MHz), Personal Communication Service (PCS: 1850–1990 MHz), and Universal Mobile Telecommunications System (UMTS: 1900–2200 MHz). Initially, the reconfigurability of the proposed antenna is achieved by attaching lumped capacitor over the slit of the radiator with values range from 1.5–4pf. The measured and simulated results reveal that the fabricated proposed antenna is capable of obtaining tunable frequency ratio from 1850MHz to 2200MHz with overall size of 21×13.5×5 mm3 that makes it suitable for handset applications and can be easily integrated inside commercial mobile handsets.

Reconfigurable antenna design approach for mobile applications and a technique for harmonics suppression

A design procedure for reconfigurable mobile antenna module is presented. A tuneable antenna, including a varactor diode placed at specific position over the radiating slot, was fabricated and tested over several targeted frequency bands (centred at 1.7, 1.8, 1.9 and 2.04 GHz) and their harmonics. A limitation of the tuneable antenna is its non-linear behaviour at the transmitter. A method to measure the radiated power from an active antenna (AA) at fundamental and harmonic frequencies is introduced to suppress the harmonic radiations of the active antenna. The experimental results on the received power show a very good capability for harmonic suppression.

Design of a planar inverted F-L antenna (PIFLA) for lower-band UWB applications

This paper examines the case for an ultrawideband planar inverted-F-L-antenna design intended for use in the lower sub-band. The antenna construction is based on the conventional inverted F, and inverted L as its feed element, and parasitic element, respectively. The optimized antenna size is 30×15×4mm3. The prototype antenna has a good return loss of −10 dB, and a 66.6% impedance bandwidth (2.8 GHz–5.6 GHz), the gain varies between 3.1 dBi and 4.5 dBi.

Miniaturized dual-band balanced antenna for LTE using meander lines

A new compact dual-band balanced antenna is proposed with meandered lines operating in the LTE bands of 700/2600MHz. It has a compact size with the overall dimensioning of 54×18× 8 mm3, in which can be simply concealed within mobile handsets. Techniques such as meandered lines are used in order to accomplish a well-matching and size reduction of antenna. The meander lines were printed on FR4 substrate with relative permittivity of 4.4 and dielectric loss tangent of 0.0017 with a thickness of 1.6 mm. The results of the present design structure were checked in terms of reflection coefficient, operational bandwidth, current surface, and radiation pattern characteristics. The results have shown that the proposed design can be an attractive candidate for use in mobile handset.