Anders Derneryd

Analysis of the microstrip disk antenna element

The circular microstrip antenna element is formed by a radiating disk closely spaced above a ground plane. It is modeled as a cylindrical cavity with magnetic walls which can be resonant in the transverse magnetic (TM) modes. The far fields and the radiation conductances for different mode structures have been calculated assuming a magnetic line current flowing along the perimeter of the disk. The directivity of a disk antenna excited in the dominant mode is between 4.8 dB and 9.9 dB, depending on the size. Losses, due to imperfect supporting dielectrics and to the finite conductivity of the conductors, have been derived by means of a perturbation technique. Graphs are given for design purposes showing the input impedance, the Q factor, and the radiation efficiency at resonance for different modes and thicknesses. The air-filled microstrip antenna has the highest efficiency and the broadest bandwidth at a given resonant frequency.

Actual Diversity Performance of a Multiband Diversity Antenna With Hand and Head Effects

Using the metric actual diversity gain (ADG), diversity performance is investigated for a compact mobile terminal prototype with two internal, triple frequency band antennas in four different cases of user interaction. ADG is presented as a preferred alternative to apparent diversity gain and effective diversity gain. Absorption due to user proximity causes degradation and imbalance in mean effective gain of the antennas over the frequency bands, contributing to a degradation in diversity performance. However, user-induced changes in the antenna patterns cause a decrease in correlation in the low frequency band, which facilitates increased diversity gain. The study reveals that a significant net diversity gain, i.e., ADG of 5-8 dB compared to a single antenna prototype, can be achieved using multiband antennas in the proximity of a user, even at low frequencies for antennas with high mutual coupling.

Extended analysis of rectangular microstrip resonator antennas

An extended theory on rectangular microstrip resonator antennas is presented using the cavity model. Radiation from all four edges of the open cavity is taken into account as well as dielectric and ohmic losses. For a rectangular microstrip antenna excited in its lowest resonance mode, losses, input conductance, and bandwidth are calculated and plotted versus frequency for some different parameters, showing that bandwidths of up to 15 percent (for a voltage standing-wave ratio (VSWR) of less than two) are possible to achieve in the X band.

Small-Cell Wireless Backhauling: A Non-Line-of-Sight Approach for Point-to-Point Microwave Links

In this paper we investigate the feasibility of using microwave frequencies for fixed non-line-of-sight wireless backhauling connecting small-cell radio base stations with an aggregation node in an outdoor urban environment, i.e. a typical heterogeneous network scenario. We study system level simulations for a point-to-point system where the wave propagation is based on diffraction over rooftops. We further investigate the effects of carrier frequency, interference, antenna height, rain, and tolerance to antenna alignment errors. It is found that the higher frequencies offer not only larger bandwidths but also higher antenna gains which would ideally work to their advantage. However, these advantages may be lost when taking antenna alignment errors and rain into account. Different frequencies simply have their different trade-offs.

Diversity antenna terminal evaluation

Simulated and measured correlation and diversity performance for a couple of two-antenna concepts are presented. The results indicate that the three-dimensional isotropic incident field is a good reference case to evaluate diversity performance in a multi-antenna application.

Application of compound coupling slots in the design of shaped beam antenna patterns

The amount of phase control realizable by resonant compound slots for application in a standing wave array is investigated. It is shown that with a proper choice of excitation coefficients, shaped beam antenna patterns can be designed with the use of resonant compound coupling slots. A procedure for designing resonant compound coupling slots in the feed waveguide of a planar array is presented. With the use of this procedure a shaped beam antenna pattern has been realized by a planar array consisting of compound coupling slots in the end-fed configuration and conventional longitudinal radiating slots. Excellent agreement between theory and experiment is found for input VSWR and radiation patterns, thus demonstrating the utility of resonant compound coupling slots. >

Broadband microstrip antenna element and array

Foam-supported highly efficient microstrip antennas are described. Theoretical and experimental results show that bandwidths up to 15 percent can be obtained at the expense of an increase in the antenna height (to about 0.1 wavelength). The performance of an array of broadband elements fed by a microstrip corporate feed network is also described.

Design of a phase/frequency scanned array antenna with non-resonant slotted ridge waveguide elements

The synthesis of a two-dimensionally scanned antenna is presented. The antenna is scanned in one direction by ferrite phase shifters and in the other direction by frequency scanned waveguides. In order to accomplish a wide electronic scan range the waveguide width has been reduced by ridge loading. The radiating elements consist of broadwall shunt slots. The characterization of the radiating slots has required the development of new design models as well as special testing techniques. The antenna requirements include a large scan sector in azimuth, low sidelobes, high pointing accuracy, and high antenna gain. These requirements demand an accurate design method and a well-controlled manufacturing process. A large antenna was designed, manufactured, and, tested, consisting of 48 waveguides, each fed through 8-bit ferrite phase shifters.<<ETX>>

Evaluation of user hand and body impact on multiple antenna handset performance

The impact of the user in mobile communication systems may strongly affect the design and placements of antennas on terminals, as well as performance and reliability of system simulations, when utilizing multiple antenna techniques such as diversity and MIMO (multiple-input multiple-output). In this paper we evaluate the user impact on antenna performance based on measurements using a realistic setup with a full (one-armed) upper body user phantom in combination with a four antenna handset mock-up in a realistic indoor office environment at 2.5–2.7 GHz. We utilize an approach where the radiation pattern of the user together with the antenna is considered as one radiating unit, and evaluate the performance impact of the user body and hand of such properties as antenna efficiency, diversity combining approaches, and potential MIMO channel performance. In combination with radiation pattern measurements, the handset-plus-phantom radiation patterns are combined with a DDPC (double-directional propagation channel) representation of measured indoor channels by utilizing a composite channel method as described in [1, 2]. Previously the impact of the user in the mobile radio channel has been analyzed, e.g., by Yamamoto et al. [3] who showed by channel measurements that the impact of a realistic user phantom compared to simplified models may not be negligible in evaluation of diversity and MIMO capacity. Li et al. [4] and Pelosi et al. [5] showed that the user hand and the terminal position inside the hand may have a severe impact on the antenna efficiency.

Channel capacity performance of multi-band dual antenna in proximity of a user

This paper presents an evaluation of single input single output (SISO), single input multiple output (SIMO) and multiple input multiple output (MIMO) channel capacities for a dual antenna prototype in proximity of a user. The dual antenna prototype mimics todays small mobile phone design in size and in comprising internal, compact, multi-band antennas. Four different user cases are evaluated by measuring the antenna radiation performance for each of the different interactions between a phantom user and the antenna. Measurements of a single antenna prototype with user are also performed for comparisons between the SISO case and the SIMO/MIMO cases. Depending on the user interaction case, the MIMO capacity of the prototype is between 40–90% at 850 MHz and 60–80% at 2100 MHz higher than the SISO performance of the single antenna prototype or the best antenna on the dual antenna prototype.