Bilal A. Khawaja

Wireless Hybrid Mode Locked Lasers for Next Generation Radio-Over-Fiber Systems

This paper demonstrates a novel technique to wirelessly injection lock a state-of-the-art 40 GHz mode locked laser and shows baseband data transmission using such a technique. This allows mode locked lasers to be used as millimeter wave modulated data sources for next generation Radio-over-Fiber systems. Binary phase shift keying data transmission rates of up to 22 Mb/s have been demonstrated for a short wireless range of 10 cm. These devices can also be used as millimeter wave phase shifters for advanced antenna beam steering systems.

Wideband E-shaped antenna design for WLAN applications

This paper presents a design, simulation and optimization study of a coaxial-fed wideband E-Shaped patch antenna that is suitable for 5 GHz WLAN applications. The bandwidth of the antenna was enhanced from 8.5% to 17.5% by changing the antenna shape from square patch to E-shaped patch. The proposed antenna gives an overall bandwidth of about 1 GHz and operates between 5-6 GHz frequency bands. The design has also been optimized to minimize the antenna size with desired characteristics and antenna width has been reduced from 19.2 mm to 15.8 mm. The antenna is designed on a glass microfiber substrate having thickness h = 3.175 mm and dielectric constant εr = 2.2. The antenna design and simulation is performed using Agilent ADS Momentum simulator. The simulation results against different E-shaped antenna parameters have been analyzed and discussed. Other antenna performance parameters like gain, directivity, return loss, radiation pattern and bandwidth have also been studied and analyzed.

Dual U-slot triple band microstrip patch antenna for next generation wireless networks

This paper presents a design, simulation and optimization study of a dual U-slot triple-band microstrip patch antenna. The designed antenna generates the triple frequency bands of 2.46GHz, 3.28GHz and 5.38GHz which can be used in the IEEE 802.16 WiMax and next generation wireless network applications. The achieved gains/bandwidths from the designed antenna for the WiMax bands are 4.2dBi/2.31%, 2.7dBi/2.41% and 1.5dBi/2.49% respectively. The proposed antenna is designed using FR4 substrate with transmission-line feeding method. A detailed simulation study is conducted to understand the behavior of the two U-slots. It can be seen from the proposed antenna design that every U-slot generates a separate resonance frequency. The third frequency band is generated, when both the U-slots are placed together in a single antenna element. A bridging element is also used to shift the three frequencies to lower bands. The proposed antenna is designed using Agilent ADS Momentum simulator. The E-plane and H-plane patterns in the results validates that the design is well-adapted to the desired triple-bands. The return loss (S11) characteristics for the triple-bands are -18.74dB at 2.46GHz, -19.91 dB at 3.28GHz and -18.98dB at 5.38GHz respectively which suggest good antenna performance. The proposed antenna can be used in future as a template to form larger arrays.

Dual BandMicrostrip patch antenna array for next generation wireless sensor network applications

In this paper, the design, Optimization and simulation of a dual-band coaxial-fed 2×2 rectangular U-Slot microstrippatch antenna array for wireless sensor network applications is presented. It operates on 2.1GHz and 3.5GHz bands. A MIMO antenna is proposed for high speed WSNs based communication standards that operates in 1-5GHz frequency range. Antenna design and simulation is performed in Agilent ADS Momentum using Rogers TMM3 substrate (εr =3.27 and h=6.35mm). The maximum achieved gain for2 x 2 U-slot rectangular patch antenna array is lldBi. Substrate losses are also taken into account during simulation process. Simple design procedure and optimization techniques are also discussed to design a single element dual-band patch antenna. The proposed array may be used as a template to form larger arrays.

Study of Millimeter Wave Phase Shift in 40 GHz Hybrid Mode Locked Lasers

An investigation into using hybrid mode-locked lasers to implement millimeter wave phase shift is presented. The phase shift is measured directly using a vector network analyzer enabling straightforward characterization of such systems. Both magnitude and phase of the modulation response are measured and a ldquoplateaurdquo is observed in the magnitude response which corresponds to the locking range of the system. Phase shifts of greater than 90deg are observed and such devices could have application in millimeter wave radio-over-fiber phased array antenna systems.

UWB wearable antenna for next generation wireless body area networks (WBANs)

The IEEE 802.15.6 is a WBAN communication standard which is covering on/off body and in body communications. The ultra wideband (UWB) is one of the possible technologies which can be utilized in future for the WBAN applications due to high data-rate transmission capability. In this paper, the design, optimization and simulation of a UWB antenna using FR4 and jeans fabric substrates is presented for on-body communication in WBANs. It operates in the 3.6-11.3GHz frequency band. The antenna simulation results i.e. reflection coefficient, 2D and 3D radiation patterns, directivity, gain and efficiency are presented. The maximum achieved gain for the UWB wearable antenna is 1.9dBi and 2.36dBi respectively for FR4 and jeans substrates. Simple design procedures and optimization techniques are discussed and the antennas are designed using Agilent advance design system - momentum simulator.

Characterisation of Multimode Fibres for Use in Millimetre Wave Radio-Over-Fibre Systems

Millimetre wave radio-over-fibre links using both single mode and, for what is believed to be the first time, multimode fibres are demonstrated over a 0-50 GHz bandwidth using a external Mach-Zehnder modulator operating at 1550 nm. The multimode fibre links show the potential for use in low cost, distributed antenna systems.

A triple-band antenna array for next-generation wireless and satellite-based applications

In this paper, a triple-band 1 × 2 and 1 × 4 microstrip patch antenna array for next-generation wireless and satellite-based applications are presented. The targeted frequency bands are 3.6, 5.2 and 6.7 GHz, respectively. Simple design procedures and optimization techniques are discussed to achieve better antenna performance. The antenna is designed and simulated using Agilent ADS Momentum using FR4 substrate (e r = 4.2 and h = 1.66 mm). The main patch of the antenna is designed for 3.6 GHz operation. A hybrid feed technique is used for antenna arrays with quarter-wave transformer-based network to match the impedance from the feed-point to the antenna to 50 Ω. The antenna is optimized to resonate at triple-bands by using two symmetrical slits. The single-element triple-band antenna is fabricated and characterized, and a comparison between the simulated and measured antenna is presented. The achieved simulated impedance bandwidths/gains for the 1 × 2 array are 1.67%/7.75, 1.06%/7.7, and 1.65%/9.4 dBi and for 1 × 4 array are 1.67%/10.2, 1.45%/8.2, and 1.05%/10 dBi for 3.6, 5.2, and 6.7 GHz bands, respectively, which are very practical. These antenna arrays can also be used for advanced antenna beam-steering systems.

A log-periodic microstrip patch antenna design for dual band operation in next generation Wireless LAN applications

In this paper, the design and simulation study of a dual-band inset-fed log-periodic microstrip patch antenna is presented for next generation Wireless LANs. The microstrip antennas are preferred for applications where small size antennas are required which leads to the drawback like narrow bandwidth. To overcome this shortcoming in microstrip antennas, several design techniques are proposed one of which is log-periodic antenna design which is studied in this paper. The aim of this study is to propose an antenna design that can operate at both Wireless LAN frequency bands of 2.4GHz and 5GHz. The designed antenna consists of four radiating elements which cover IEEE 802.11 a/b/g Wireless LAN bands. Two inset-fed antenna elements are used for single frequency band i.e. for 2.4GHz and 5GHz bands. The dimensions of single element were calculated using transmission-line model. The layout of the antenna was simulated in momentum - an EM tool of Agilents Advance design (ADS) system simulator.

A Millimeter-Wave Self-Oscillating Mixer Using a Mode-Locked Laser

This paper presents a study of millimeter-wave optoelectronic downconversion using the self-oscillating mixer concept. Baseband data are transmitted using a 40-GHz electrical carrier; however, detection only requires a much lower speed photodiode. Both homodyne and heterodyne configurations are presented with the former requiring injection locking which can limit the maximum baseband data rate.