Dual-circularly-polarized balanced-fed dielectric rod antenna for 60-GHz point-to-point wireless communication

The design of a dual-circularly-polarized balanced-fed dielectric rod antenna for 60-GHz point-to-point communication is described and realized. The measured gain and axial ratio are 15dBi and below 0.5dB, respectively

Millimeter-wave antenna with adjustable polarisation

A millimeter-wave antenna is presented that has an adjustable polarization. The polarization can be controlled by the input signal of the antenna and therefore no separate RF switch is needed. A completely planar feed network has been designed that employs branch-line couplers that allow to vary polarization depending on the input signal. The antenna has been realized and the concept of polarization diversity is demonstrated. Measurement results are in agreement with simulated results and validate the performance of the antenna

Short-term frequency scaling of clear-sky and wet amplitude scintillation

For the design of uplink power control (ULPC) systems that can compensate for different types of fading, the short-term frequency scaling factor of all types of fading is needed. Attention is focused on the short-term frequency scaling factor of clear-sky amplitude scintillation and amplitude scintillation (using the measurements of the 12.5/20/30GHz beacon signals) occurring with rain attenuation simultaneously, often referred to as wet amplitude scintillation. It is shown that these factors are strongly variable: they depend on various meteorological parameters and on the aperture illumination efficiency of the receiving antenna. In addition, it is shown that amplitude scintillation can only be compensated partly by means of ULPC, owing to the limited correlation of amplitude scintillation measured on two radiowaves with different carrier frequencies propagating along the same path simultaneously. Furthermore, a new procedure is presented to separate rain attenuation and amplitude scintillatio

Multiple-beam groundstation reflector antenna system : a prelimary study

A wide-scanning multiple-beam reflector antenna, two systems are investigated. A bifocal antenna, designed with the use of an existing method, appears to be unsuitable for wide-angle scanning. A dual-reflector offset torus-antenna showed promising results. As an illustration of its benefit, a possible application is examined: the simultaneous reception of signals from a number (n) of geostationary direct broadcast satellites with mutual distance of 6 degrees. Using this antenna yields advantage when compared, with respect to the total required reflector area, with n separate antennas.<br/

Planar beam-forming array for broadband communication in the 60 GHz band

A planar beam-forming antenna array is proposed that operates in the 60 GHz frequency band. The array consists of 6 balanced-fed aperture-coupled patch antenna elements [2] that are placed in a circular configuration. The resulting array has a maximum gain of 14 dBi and a 3 dB scan range of plusmn50 degrees. To demonstrate the performance, test arrays have been implemented with accompanying feed networks that apply the appropriate phase distribution over the array for beam-forming at several specific scan angles. Measurements validate the proposed array configuration

Diagnostic analysis of radio propagation in UMTS networks using high-resolution angle-of-arrival measurements

This work describes high-resolution propagation measurements performed as a diagnostic survey in an operational UMTS network. The results were obtained using the measurement system previously presented in. Measurements were performed in a dense urban environment in Amsterdam, the Netherlands. Results showed that the measurement approach can be used to create a setup that is similar to the actual network scenario, and that is capable of accurately identifying the dominant propagation effects while moving through the environment. The results are especially important for mobile-system operators, because they revealed some of the causes of inadequate propagation prediction. This underlined the limitations of propagation-prediction models currently used by most mobile-system operators, and the importance of accurate propagation information to obtain the optimal network configuration

A tree-scattering model for improved propagation prediction in urban microcells

This paper presents a model for the scattering of radiowaves from the canopy of a single tree. The canopy is modeled as a cylindrical volume containing randomly distributed and oriented cylinders, representing the branches, and thin disks, representing the leaves. A simple expression for the incoherent scattered field outside the canopy is obtained using Twersky's multiple scattering theory. This expression is shown to agree well with results of scattering measurements on a live tree typical of those found in urban environments. The scattering model can be readily incorporated in ray-based propagation prediction tools that assist the planning of microcellular radio networks. This involves the use of so-called tree-scattered rays, which interact at the tree centers. Path loss predictions generated with the aid of the new model are shown and compared with measured data to illustrate the considerable improvement in prediction accuracy that can be achieved in realistic urban microcellular scenarios by taking into account the scatter from trees

Application of five-sector beam antenna for 60 GHz indoor wireless communications

The application of a switched five-sector beam antenna in high-speed indoor wireless LAN systems operating in the 60 GHz band is investigated. The effects of line-of-sight obstruction as well as the influence of the access-point antenna height are experimentally studied in a typical small-sized office room. The results are compared with those obtained with classical antenna configuration

Comments on "A shaped reflector antenna for 60-GHz indoor wireless LAN access points"

The author comments that the shaped reflector antenna principles and theory of Smulders, Khusial and Herben (see ibid., vol.50, p.584-91, Mar.2001) are based on the papers described by Kumar (see Proc. Montech '86 IEEE Conference on Antennas and Communication, 1986, IEEE Cat. No. TH0156-0, Inst. Elect. Eng. Proc., vol.134, p.106-108, 1987 and Technology Symposium, 1990). These papers described the X-band, circularly polarized shaped beam telemetry antenna suitable for retransmitting the radar data back to an earth terminal. Smulders et al. have used the same principle, and similar types of radiation patterns are produced. However, two points are different in their paper: (1) the design frequency (60 GHz) and (2) the application of antenna for indoor wireless LAN access points. Therefore, they authors should have referenced Kumar's papers. Smulders et al. agree with Kumar's comments that reflector shaping is nothing new. However, we took into account diffraction effects (by applying the uniform theory of diffraction) whereas the shaping in the paper of Kumar is based on geometrical optics, only. We showed that according to our approach, a more smooth illumination function can be achieved and how the smoothing effect depends on the amount of edge illumination. We also showed in which way the spatial field deviation can be minimized and that this could save a few decibels in the link budget