Antenna Hardware Research Articles

Design of concentric ring antenna array for a reconfigurable isoflux pattern

This report presents a novel design of concentric ring antenna array for a reconfigurable isoflux pattern. The array considers 61 disk patch antennas including mutual coupling by using the cavity model at the frequency of 2.8 GHz. The problem consists in finding out a few levels of excitations for the disk patch antennas. Harmony search algorithm and particle swarm optimization are implemented for this optimization problem. This novel design permits to reduce the complexity of the antenna hardware in the whole antenna system mounted in a satellite, where the volume occupation and heat dissipations are critical issues.

Ultra-wideband pulse shaping: bypassing the inherent limitations of the Gaussian monocycle

UWB impulse radio transmissions are power limited as they must respect a frequency mask with low total permitted power and severe isolation requirements for the GPS band. Shaping of the short UWB impulse maximizes transmit power subject to these constraints. We have previously published results for intricate pulse shaping in the optical domain that achieves record levels of power transmission. The most successful pulse shaping techniques in the electrical domain have been achieved with derivatives of the Gaussian pulse shape. The Gaussian monocycle is a low performance choice in terms of transmit power, but nonetheless the subject of intense research activity. In this paper we compare and contrast these UWB pulses, and quantitatively compare their performance in realistic systems (specific RF and antenna hardware). There is the perception that failings in the pulse shape (especially for the monocycle) can be compensated by simple highpass filter and the bandpass nature of the UWB antenna. We fabricate and characterize two UWB antenna designs available in the literature, as well as one commercial antenna. We use our optical pulse shaping device to experimentally investigate the three different pulse shapes and measure their transmitted power spectral density with each of the UWB antennas. We find that the monocycle is significantly less powerful than the others. The fine pulse shaping available in optical processing provides 1.7 to 2.9 dB gain over the electrical processing methods, depending on the antenna used.

Smart Antenna UKM Testbed for Digital Beamforming System

A new design of smart antenna testbed developed at UKM for digital beamforming purpose is proposed. The smart antenna UKM testbed developed based on modular design employing two novel designs of L-probe fed inverted hybrid E-H (LIEH) array antenna and software reconfigurable digital beamforming system (DBS). The antenna is developed based on using the novel LIEH microstrip patch element design arranged into uniform linear array antenna. An interface board is designed to interface to the ADC board with the RF front-end receiver. The modular concept of the system provides the capability to test the antenna hardware, beamforming unit, and beamforming algorithm in an independent manner, thus allowing the smart antenna system to be developed and tested in parallel, hence reduces the design time. The DBS was developed using a high-performance floating-point DSP board and a 4-channel RF front-end receiver developed in-house. An interface board is designed to interface to the ADC board with the RF front-end receiver. A four-element receiving array testbed at 1.88–2.22 GHz frequency is constructed, and digital beamforming on this testbed is successfully demonstrated.

Optimised design of an ISM band antenna using a jumping genes methodology

An improved design of industrial, scientific and medical (ISM) band folded-patch antenna is presented. It is simple to manufacture and has less potential for manufacturing error than a previously presented design. Jumping genes evolutionary algorithm is applied for optimising antenna performance. A solution selection methodology is also designed to select the best solution among several alternatives after the optimisation process. Antenna hardware was fabricated and measured to verify the simulation result. Both simulated and experimental results are in good agreement. It is capable of covering three ISM bands at 2.400-2.480, 5.150-5.350 and 5.725-5.825 GHz, which is ideally suitable for short-range wireless applications.

Comparison of Antenna Array Systems Using OFDM for Software Radio via the SIBIC Model

This paper investigates the performance of two candidates for software radio WLAN, reconfigurable OFDM modulation and antenna diversity, in an indoor environment. The scenario considered is a 20m × 10m × 3m room with two base units and one mobile unit. The two base units use omnidirectional antennas to transmit and the mobile unit uses either a single antenna with equalizer, a fixed beamformer with equalizer, or an adaptive beamformer with equalizer to receive. The modulation constellation of the data is QPSK and 16-QAM. The response of the channel at the mobile unit is simulated using a three-dimensional indoor WLAN propagation model that generates multipath components with realistic spatial and temporal correlation. An underlying assumption of the scenario is that existing antenna hardware is available and could be exploited if software processing resources are allocated. The results of the simulations indicate that schemes using more resources outperform simpler schemes in most cases. This implies that desired user performance could be used to dynamically assign software processing resources to the demands of a particular indoor WLAN channel if such resources are available.

Automated software module reconfiguration through the use of artificial intelligence planning techniques

One important approach to enhancing software re-use is through the creation of large-scale software libraries. By modularising functionality, many complex specialised applications can be built up from smaller reusable general-purpose libraries. Consequently, many large software libraries have been formed for applications such as image processing and data analysis. However, knowing the requirements and formats of each of these routines requires considerable expertise – thus limiting the usage of these libraries to experts. An approach is described to enable novices to use complex software libraries. In this approach, the interactions between, and requirements of, the software modules are represented in a declarative language based on artificial intelligence (AI) planning techniques. The user is then able to specify their goals in terms of this language-designating what they want accomplished, instead of how to do it. The AI planning system then uses this model of the available subroutines to compose a domain specific script to fulfill the user request. Three such systems developed by the Artificial Intelligence Group of the Jet Propulsion Laboratory and described. The multimission VICAR planner (MVP) was deployed in 1994 and used to support image processing for science product generation for the Galileo mission. MVP reduced the time for filling certain classes of requests from 4 h to 15 min. The automated SAR image processing system (ASIP) was deployed in 1996 to the Department of Geology at Arizona State University to support aeolian science analysis of synthetic aperture radar images. ASIP reduces the number of manual inputs in science product generation tenfold. Finally, the DPLAN system reconfigures software modules that control complex antenna hardware in configuring antennas to support a wide range of tracks for NASA's Deep Space Network of communications and radio science antennas.

Antenna research at the Communications Research Centre

An overview is presented of the antenna research carried out by the Directorate of Antennas and Integrated Electronics (DAIE) of the Communications Research Centre (CRC). The antenna research within the DAIE can be categorized into two groups: antenna-hardware development and electromagnetic-software development. Research in antenna hardware has focused on printed multi-layer arrays, dielectric-resonator antennas, ferrite antennas, active-circuit integration, and low-loss feed networks. Research in electromagnetic software includes the development of three-dimensional transmission-line-matrix (TLM) code, and the application of cellular automata (CA) techniques for the analysis and modeling of antennas, microwave circuits, and general electromagnetic phenomena, such as scattering. This article concentrates on the antenna-hardware research and development within the DAIE. Radiation patterns are considered.

Gravitational-wave versus electromagnetic-wave antennas

Unlike radio waves, gravitational waves have not yet been conclusively detected. However, there is indirect evidence from the slow decay of binary-pulsar systems. The author describes some of the gravitational antenna hardware, and tries to relate it to the more-familiar antennas of radio, radar, and astronomy. Particularly noted is the phenomenon that an electromagnetic antenna readily intercepts the time-varying wave, whereas a gravitational wave readily passes right through its counterpart, with minuscule energy transfer. >

Vector Winds from a Single-Transmitter Bistatic Dual-Doppler Radar Network

A bistatic dual-Doppler weather radar network consisting of only one transmitter and a nontransmitting, nonscanning, low-cost bistatic receiver was deployed in the Boulder, Colorado, area during 1993. The Boulder network took data in a variety of weather situations, including low-reflectivity stratiform snowfall, several convective cells, and a hailstorm. Dual-Doppler vector wind fields were retrieved and compared to those from a traditional, two-transmitter dual-Doppler network. The favorable results from these comparisons indicate that the bistatic dual-Doppler technique is viable and practical. Bistatic multiple-Doppler networks have significant scientific and economic advantages accruing from the use of only single sources of illumination. Individual spatial volumes are viewed simultaneously from multiple look angles, minimizing storm evolution–induced errors. The passive receivers in a bistatic network do not require expensive transmitters, moving antenna hardware, or operators. Thus, they require only a small percentage of the investment needed to field traditional transmitting radars. Bistatic systems can be deployed affordably to provide three-dimensional fields of full-vector winds, including directly measured vertical precipitation particle velocities for numerous applications in meteorological research, aviation, forecasting, media, and education.

Missile base mounted microstrip antennas

Proof of the feasibility of aft mounting low-profile antennas on reentry vehicles is presented. This is an application of state of the art antenna hardware. Aft mounting presents the best reentry environment to antenna hardware, and its practicality has been demonstrated. Microstrip antenna principles can be used to produce very rugged antennas. Their low profile reduces many interface, mechanical, and survival problems. The pattern coverage for these vehicles must be toward the fore direction. This type of pattern requires an interaction between the vehicle and the antenna when the antenna is effectively shadowed from that direction. This paper describes the results obtained by actual experimental hardware. Contoured elements were used, as were foreshortened elements. These elements demonstrated ability to be fit around other aft equipment. The versatility of these elements were further demonstrated by tailoring them for two different types of coverage to accommodate different vehicle operational requirements.

Deflection analysis of supporting structures for antennas to be used in a mobile telephone system

Supporting structures for antenna hardware for a new high-capacity mobile telephone system (HCMTS) are being designed to meet operational electrical requirements and to survive extreme weather conditions. Systematic techniques are being used to choose dimensions for critical elements in the trade-off of cost versus performance.