Review of antenna technologies for very high frequency Data Exchange Systems

Measurement methodology and results of measurements of the man-made noise floor on HF in the Netherlands

Radio noise of man-made origin has been measured and studied since the 50s of the past century. From that time on, especially in the last two decades, the electromagnetic environment has changed due to the wide spread and increasingly complicated electronic and computing equipment in domestic and work premises. Not only the character of man-made...

Field experiments with a dual-frequency-band underwater acoustic network

For remote deployment of unmanned/autonomous underwater vehicles that, for reasons of size, power usage and cost, communicate acoustically in relatively high frequency bands, a backbone underwater acoustic network needs to support multiple frequency bands with the communication streams being able to cross over between bands as required. This...

Near field resolution measurements with the leaky wave antennas

N-path filters exploiting switched-series-R-C networks can realize high-Q blocking-tolerant band-pass filters. Moreover, their center frequency is flexibly programmable by a digital clock. Unfortunately, the time variant nature of these circuits also results in unwanted signal folding. This paper proves analytically that folding can be reduced...

Beamformer with constant-Gm vector modulators and its spatial intermodulation distortion

Spatial interference rejection in analog adaptive beamforming receivers can improve the distortion performance of the circuits following the beamforming network, but is susceptible to the nonlinearity of the beamforming network itself. This paper presents an analysis of intermodulation product cancellation in analog active phased array receivers...

Performance of acoustic communications for AUVs operating in the North Sea

The effect of sound speed profile on shallow water shipping sound maps

Sound mapping over large areas can be computationally expensive because of the large number of sources and large source-receiver separations involved. In order to facilitate computation, a simplifying assumption sometimes made is to neglect the sound speed gradient in shallow water. The accuracy of this assumption is investigated for ship...

Potential of dynamic spectrum allocation in LTE macro networks

In recent years Mobile Network Operators (MNOs) worldwide are extensively deploying LTE networks in different spectrum bands and utilising different bandwidth configurations. Initially, the deployment is coverage oriented with macro cells using the lower LTE spectrum bands. As the offered traffic (i.e. the requested traffic from the users)...

Observations and modeling of fog by cloud radar and optical sensors

Fog is a significant factor affecting the public traffic because visibility is reduced to a large extent. Therefore the determination of optical visibility in fog from radar instruments has received much interest. To observe fog with radar, high frequency bands (millimeter waves) have the best option. A 35 GHz cloud radar at the Cabauw...

Observations and modeling of fog by cloud radar and optical sensors

Fog is a significant factor affecting the public traffic because visibility is reduced to a large extent. Therefore the determination of optical visibility in fog from radar instruments has received much interest. To observe fog with radar, high frequency bands (millimeter waves) have the best option. A 35 GHz cloud radar at the Cabauw...

Annoyance caused by low frequency sounds: Spectral and temporal effects

The objective of the present laboratory studies was to enable refinements of the current rating procedure for low frequency sounds. To increase our insight into a relevant spectral issue, groups of adjacent frequency bands around 40, 50, and 63 Hz were presented at various sound level combinations. It was concluded that an energy-based summation...

The Herschel-Heterodyne Instrument for the Far-Infrared (HIFI)

Aims. This paper describes the Heterodyne Instrument for the Far-Infrared (HIFI) that was launched onboard ESA's Herschel Space Observatory in May 2009. Methods. The instrument is a set of 7 heterodyne receivers that are electronically tuneable, covering 480-1250 GHz with SIS mixers and the 1410-1910 GHz range with hot electron bolometer (HEB)...

EBG-based 60 GHz on-chip antenna in passive silicon

At most frequencies currently in use for short range data communication the available bandwidth is limiting the data rate. However, around 60 GHz there is an unlicensed frequency band with ample bandwidth appointed to support high data rate communication. Moreover, semiconductor technology for this frequency range is maturing and price levels...

Effects of band-limited noise on human observer performance

Perception tests establish the effects of spatially band-limited noise and blur on human observer performance. Previously, Bijl showed that the contrast threshold of a target image with spatially band-limited noise is a function of noise spatial frequency. He used the method of adjustment to find the contrast thresholds for each noise frequency...

Small maritime target detection through false color fusion

We present an algorithm that produces a fused false color representation of a combined multiband IR and visual imaging system for maritime applications. Multispectral IR imaging techniques are increasingly deployed in maritime operations, to detect floating mines or to find small dinghies and swimmers during search and rescue operations. However...

Wideband localization of the dominant leaky wave poles in dielectric covered antennas

This letter discusses the properties of printed antennas whose radiation patterns (their directivity or their shape) are enhanced by means of dielectric superlayers which support leaky waves. In particular the characterizing complex leaky wave poles of the spectral Green Function are approximated analytically, for the first time over large...

Frequency selective surfaces for the RCS reduction of low frequency antennas

This paper describes the design and measurement of a two-layers gangbuster Frequency Selective Surface (FSS). The FSS is aimed to limit the RCS of the compartment of a ship's mast housing telecommunication antennas and should guarantee a pass-band at low frequencies, in the operating band of the antennas, while reflecting the incoming signal at...