Feed radiation effects in sequentially rotated microstrip patch arrays

Feed radiation effects in microstrip patch arrays with coplanar feed networks result in increased sidelobe levels and reduced efficiency. A modified implementation of the sequential rotation feed principle is used to reduce feed radiation. Computed results confirmed by measurements show sidelobe reduction of up to 10dB. First-order estimates of efficiency improvement in large arrays are also given.     

Local-Line Single-Mode Optics--Viable Options for Today and Tomorrow

Introducing optical transmission into the local network poses a number of severe economic and technological problems. In this paper, we address these problems assuming a future requirement for a wholly monomode transmission network through long/short haul and local lines. The key considerations therefore involve the economic realization of systems in the 2-140 Mbit/s range. Specific laboratory designs at 2, 8, and 34 Mbits/s employing uni- and bidirectional operation are discussed. Field experience at 1.3 and 1.5 μm using very low cost unidirectional and bidirectional systems is reported, including systems based upon directional couplers, wavelength-duplex, and "piggyback" schemes.     

A direct plate count method for detecting E. coli in frozen food by detecting indole in colonies

A medium giving maximum indole production colonies of Escherichia coli has been defined and includes diethylaminoethylcellulose which restricts the spread of indole through the agar medium. A reagent based on p-dimethylaminocinnamaldehyde has been developed to give optimum indication of indole production. A simple method which will identify E. coli in cultures obtained from selective media is described and an extension, including a resuscitation stage, devised for rapid and direct quantitation of E. coli from frozen foods.     

Observation of two-colour gain saturation in an optical amplifier

We have measured changes in small-signal gain spectra of an optical amplifier caused by the presence of a second signal at a different wavelength. The results are applicable to the use of amplifiers in wavelength-division-multiplexed systems. These spectra also provide a measurement of the spectrum of ?, the linewidth-broadening factor.