A novel multi-band multiple circular loop monopole antenna is presented. Thr three outer loops have a size ratio of 2 while the feed monopole is a disc, resulting in a quasi-log periodic performance. A method for controlling the radiation pattern, which gives better results than the circular disc monopole at higher operating frequencies, is presented. The proposed antenna performance is also compared with that of the fractal Sierpinski gasket monopole.

C.T.P. Song, P.S. Hall, H. Ghafouri-Shiraz, and D. Wake School of Electrical and Electronic Engineering University of Birmingham Edgbaston, Birmingham B15 2TT, U. K. Email: songp@eee-fs7.bham.ac.uk School of Electrical & Electronic Engineering (South Spine Block S1) Nanyang Technological University , Nanyang Avenue, Singapore 639798 B.T. Advanced Communications Technology Centre, Adastral Park, Martlesham Heath, Ipswich, Suffolk, IP5 3RE, U. K.

A novel method is presented for achieving a complete RF front end product equipped with its radiator within a single chip package. This packaging technique provides an alternative solution to problems associated with reduced size antennas implemented on gallium arsenide (GaAs) substrates, such as restoration of the antenna gain by 15 dB. This configuration will help to reduce manufacturing costs associated with connecting the antenna to the RF front-end chip.

Two novel triple band planar inverted F antennas (PIFAs) are presented. The first antenna is realised by housing a dual frequency L-shaped spur line loaded PIFA element within the lower resonance PIFA element. The second antenna is realised by embedding two single element PIFAs within a quarter-wave patch. For both antennas, an isolation, of better than -15 dB between the feed peas and a good agreement between simulation and measurement results was obtained.

A novel configuration of the Sierpinski triangular gasket antenna is proposed. A quasi-log-periodic performance was achieved for the operating bands of GSM, DECT and WLAN by using a new band spacing control technique. This design enhances the input matching performance to well over -10dB with a 50 Ohm feed.

A parallel feed slacked fractal antenna using the square Sierpinski and diamond Sierpinski carpet is introduced. The design achieves a good input impedance match throughout the passband (1-20GHz) but occasional slight mismatch occurs. Three different experimental results are shown and the measured gain of these antennas is generally > 0dBi. These antennas are suitable for applications in picocell environments for the operating bands of GSM, DECT and WLAN systems.

A high capacity millimetre-wave fibre-radio system with an elegant return path has been demonstrated for the first time using a number of novel techniques. A 60 GHz carrier signal was generated using a master/slave DFB laser configuration and a remote upconversion scheme was used to provide a fully transparent link for the data signal (120Mb/s QPSK and 20 FM TV channels). Furthermore, an electroabsorption modulator was used as a full duplex transceiver to provide an attractive strategy for the return path.

Cellular telephone handsets are now being designed to have dual-mode capabilities, In particular, there is a requirement for internal antennas for GSM and DCS1800 systems, This paper describes a novel planar dual-band inverted-F antenna for cellular handsets, which operates at the 0.9-GHz and 1.8-GHz bands, The dual-band antenna has almost the same size as a conventional inverted-F antenna operating at 0.9 GHz and has an isolation between bands of better than 17 dB, The bandwidths of the antenna are close to those required for the above systems, Good dual-band action is also obtained for other frequency ratios in the range of 1.3-2.4. Studies also show that the dual-band antenna can operate with one or two feeds, A finite-difference time-domain analysis has been shown to give calculated results close to those measured.

Currently, there are many personal mobile satellite (MSS) systems in various stages of concept, design, and operation. One of them is the low earth orbit system (LEO), which requires two frequency operation at S and L band. At present, a planar dual-band antenna at S and L bands has been developed by using a circular patch and a short circuited ring in a stacked configuration. However, a single layer antenna would have the desirable feature of easy fabrication and low cost. In 1995, Salvador et al. developed a dual-band circularly polarized antenna based on the cross patch antenna by adding half-wavelength square patches in the four empty spaces among the arms of the cross. The dual-band antenna has compact structure and operates at two frequencies with a ratio in the range 2.9-3.2. However, in some cases such as handset antenna for mobile LEO satellite system terminals, a dual-band circularly polarized antenna with a frequency ratio of -1.5 is required. In this paper, a single layer dual-band antenna at S and L band has been developed by use a cross patch with four quarter wavelength patches printed in the empty spaces among the arms of the cross. The dual-band antenna, which we have designed, has less mutual coupling between the two bands than Salvador's antenna due to the using of quarter wavelength patches. Parameters of the antenna, including input return loss, mutual coupling, bandwidth are presented and discussed

Arrays of integrated active locked antenna oscillators can be used in 60 GHz radio on fibre modules to give increased power and low cost. As part of an ongoing study of the configuration of such modules, we have examined the effects of modulation on the array performance. Amplitude and frequency modulation are inappropriate and initial results show that the data rate for phase shift keying is limited by the oscillator resynchronisation speed. Also, the antenna radiation pattern is altered during the unlocked-state of the array

A completely passive radio access point for future high capacity short range wireless networks has been demonstrated. This concept is based on a single component, an unbiased electroabsorption modulator, which acts as a passive transceiver at the remote side of an analogue optical link.

A broad-band 60-GHz fiber-radio transmission experiment has been performed using a combination of novel techniques, The 60-GHz carrier signal was generated using a master/slave (M/S) distributed-feedback (DFB) laser configuration, which gave high purity and high power with very wide frequency tunability, The data path was separated in the wavelength domain from the carrier path so that a remote upconversion scheme could he used to provide a fully transparent link. An electroabsorption modulator (EAM) was used as a full duplex transceiver so that bidirectional optical transmission could be implemented without the need for a laser at the remote site, Transmission of a 120-Mb/s QPSK signal over a fiber span of 13 km and a radio path of 5 m was demonstrated, Furthermore, the downstream optical signal contained the 120-Mb/s QPSK signal multiplexed with 20 channels of TV. The upstream optical signal consisted of 120-Mb/s QPSK data only, Good error performance was simultaneously achieved in both directions.

A new technique is proposed and demonstrated for the optical generation of high power, high purity millimetre-wave signals, which uses optical heterodyning of two singlemode lasers to generate a beat signal in a photodiode. The lasers are in a series (master/slave) configuration, and very low phase noise is produced in the beat signal simply by subharmonic electrical injection of the slave laser.

Demand for broadband services is expected to increase dramatically over the next decade. Optical fibre and millimetre-wave radio are both capable of supporting the large bandwidth requirements associated with these services. Millimetre-wave radio systems, operating at the 60 GHz region, such as the RACE Mobile Broadband System or radio LANs, are flexible and offer the advantage of expedient provision. It is likely, therefore, that a hybrid network comprising both radio and fibre will play a significant role in broadband local-access systems. One of the principal advantages of the fibre-fed radio technology is the freedom to concentrate some of the remote equipment at a central site, where these factors are more easily controlled. Expensive equipment can be shared among a number of radio nodes, resulting in a reduced complexity at the radio node. This paper suggests a new configuration for the integration of millimetre wave and optoelectronic devices, and describes the design of a diplexer-antenna unit suitable for the remote site of a fibre-fed radio system. Also it gives experimental results on optical injection locking of mutually coupled patch antenna oscillators, designed for such radio nodes

Communication systems incorporating both millimetre-wave radio and optical fibre elements are very attractive for transmitting broadband signals. Radio on fibre systems is expected to play a significant role in telecommunication networks such as interactive multimedia services (IMS), intelligent vehicle highway systems (IVHS), mobile broadband services based on pico-cellular architecture (MBS), and high speed millimetre-wave wireless local area networks (WLAN). Asignificant advantage of the radio on fibre technology is the concentration of expensive equipment at a central location which can be shared among a number of remote sites. For any transmission system, practical issues such as size, weight, reliability, cost and power consumption of remote equipment are very important. This paper identifies the major issues of the radio on fibre system and suggests new system configurations for the integration of microwave/millimetre wave and optoelectronic devices.

A 120 Mbit/s QPSK radio signal has been transported over 100 km of optical fibre and then transmitted on a 60 GHz carrier in free-space. This was achieved using an injection-locked master/slave DFB arrangement to generate the carrier centrally and a remote modulation architecture for mixing the carrier with data signals.

High-purity 60-GHz signals, generated using a dual-mode DFB semiconductor laser, have been transmitted over 100 km of standard optical fiber with no observable degradation in purity. This device is shown to be a simple and compact optical source of high-purity 60-GHz signals for long-reach fiber-fed millimeter-wave radio systems.