Notification:
We are currently experiencing intermittent issues impacting performance. We apologize for the inconvenience.
By Topic

Microwaves, Antennas and Propagation, IEE Proceedings

Issue 1 • Date 19 Feb. 2005

Filter Results

Displaying Results 1 - 8 of 8
  • Analysis of mobile terminal diversity antennas

    Publication Year: 2005 , Page(s): 1 - 6
    Cited by:  Papers (5)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (602 KB)  

    Antenna diversity has for many years been deployed at the base station to provide significant diversity gain. More recently, diversity has also been implemented at the mobile and it has been observed through measurement that antennas still give low correlation even when closely spaced. The paper analyses why decorrelation exists mainly due to angular diversity effects from the two antennas and mutual coupling between them. Although there is low correlation there is still often a reduction in efficiency when antennas are close together, so this is also investigated to see what scope there is for diversity at the mobile. The impact on efficiency will then determine what effect is made on the diversity system as a whole. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Radiation efficiency, correlation, diversity gain and capacity of a six-monopole antenna array for a MIMO system: theory, simulation and measurement in reverberation chamber

    Publication Year: 2005 , Page(s): 7 - 16
    Cited by:  Papers (90)  |  Patents (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (882 KB)  

    A six-monopole circular antenna array for use in a MIMO system is considered. The authors show how to calculate the embedded element patterns, both by classical analytical modeling and by the method of moments. Thereafter, these are used to calculate the radiation efficiency of each embedded element, correlation and diversity gain, as well as the maximum average capacity of the MIMO system when the array is located in a rich scattering environment. The theoretical value for the capacity is obtained by numerically distributing many plane wave sources statistically uniformly over 4π, letting them illuminate the calculated embedded element pattern and using Shannon's capacity formula on the received wave amplitudes. The calculated results are compared with measurement in a reverberation chamber, representing a similar scattering environment. The agreement is good. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Rain height variability in the Tropics

    Publication Year: 2005 , Page(s): 17 - 23
    Cited by:  Papers (7)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (608 KB)  

    Most prediction methods relating to propagation in rain and other hydrometeors take into consideration the height of the melting layer in order to separate the effects of rain from ice. Here, we present the annual variability of this height, from five years' of data from the precipitation radar on board the Tropical Rainfall Measurement Mission (TRMM) satellite. The variability is derived for latitudes ranging from -30° to +30°, and compared with the corresponding freezing heights derived from the ECMWF reanalysis data. The two sets of heights show a strong variation with latitude, with the tropics showing the narrowest distribution. Their differences also show a latitude dependence, and indicate that the melting layer thickness is more variable for the subtropics. The implications are examined with reference to hydrometeor scatter interference. The recommended global standard prediction procedure for this mode of interference is evaluated using the variable distribution of the melting layer heights and their effects are examined in terms of the overall interference signal levels at 11 GHz and 30 GHz. When compared with the results using the fixed distribution specified in the current recommendation, small but significant differences at the 0.01 time percentages are observed, particularly for the 30 GHz case. The evaluation of an enhanced version of the procedure shows that significant differences can be observed even at 11 GHz, thus demonstrating the need to use a latitude-dependent rain height variability for the full evaluation of rain scatter interference levels. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Circular polarisation in a double-ridge waveguide

    Publication Year: 2005 , Page(s): 25 - 30
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1069 KB)  

    The existence of planes of circular polarisation of the alternating magnetic field in any waveguide is an important feature in its description. The main purpose is to investigate its existence in a ridge waveguide. While this structure does not support any plane of circular polarisation in its trough regions, it does support it on the symmetry plane revealed by bisecting the waveguide by a suitable H-plane electric wall. An experimental realisation of a new nonreciprocal ferrite isolator in this type of waveguide is included. The nature of the polarisation of the magnetic field at the open faces of a dielectric filler between the ridges is separately investigated using a dedicated finite element solver. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Element-free method for the analysis of arbitrarily-shaped hollow conducting waveguides

    Publication Year: 2005 , Page(s): 31 - 34
    Cited by:  Papers (2)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (501 KB)  

    The element-free method, which originates from computational mechanics and has been applied in electrostatic problems, is modified and extended to the Helmholtz wave equation for the computation of the cut-off wavenumbers of arbitrarily-shaped hollow conducting waveguides. The method is validated by comparison with published results on L-shaped, single-ridged, double-ridged, and rectangular waveguides with rounded corners. It is found that the cut-off wavenumbers can be accurately determined by the element-free method. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Investigations on the propagation characteristics of the substrate integrated waveguide based on the method of lines

    Publication Year: 2005 , Page(s): 35 - 42
    Cited by:  Papers (76)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (1095 KB)  

    A rigorous full-wave approach based on the method of lines (MoL) is presented to analyse the propagation characteristics of substrate integrated waveguides (SIWs), in which a generalised matrix eigenvalue equation is derived instead of the conventional transcend equation, greatly improving the computing efficiency. The use of an efficient Z-transform absorbing boundary condition (Z-ABC) further improved the accuracy of the calculated propagation constants. Finally, two empirical equations are proposed for the propagation constants of SIWs, which gives a simple but efficient tool in designing substrate integrated waveguide components. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Design and measurement of gyrator and isolator using ferrite coupled microstrip lines

    Publication Year: 2005 , Page(s): 43 - 46
    Cited by:  Papers (1)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (728 KB)  

    Recently reported structures of gyrators and isolators using sections of microstrip ferrite coupled lines (FCL) have been designed and tested. For the first time the feasibility of such devices has been checked experimentally. A previously predicted effect of the frequent change of operation direction in the frequency range has been confirmed by simulated and measured results. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.
  • Microstrip resonator sensors for determination of complex permittivity of materials in sheet, liquid and paste forms

    Publication Year: 2005 , Page(s): 47 - 54
    Cited by:  Papers (10)
    Save to Project icon | Click to expandQuick Abstract | PDF file iconPDF (794 KB)  

    The microstrip patch resonator in several configurations can be used for determination of the dielectric constant and the loss tangent of materials available in sheet, paste and liquid forms. A suspended patch resonator was developed to determine the dielectric constant and loss tangent of wax, kerosene, petrol and vaseline. The measured dielectric constant of the sample is within ± 2% and the loss tangent has a variation ±0.001 for the sample with moderate loss. View full abstract»

    Full text access may be available. Click article title to sign in or learn about subscription options.