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A novel through wall imaging method employing a discrete set of quick-look images (via a fixed aperture antenna array) was presented. This snapshot method was compared to the conventional SAR imaging approach. It was shown that the new method produced images of nearly the same quality as those of SAR for through wall imaging. In addition, an imaging system design has been proposed which employs a...
This paper presents a concept for a satellite-based solution for assured communications for mobile public safety groups, law enforcement vehicles and other first responders. System connectivity is assured under normal operating conditions through a combination of wireless base stations and, in areas with minimal or no existing terrestrial communications infrastructure or following a disaster, satellite...
A planar lambda/8-PIFA with a coupling feed for achieving GSM850/900/1800/ 1900/UMTS operation in the mobile phone has been proposed and studied. With penta-band operation obtained for WWAN communication, the proposed lambda/8-PIFA occupies a small area of 7 times 40 mm2 on an inexpensive 1.6-mm thick FR4 substrate. The compact size of the proposed PIFA also makes it promising to be embedded inside...
This paper introduces an efficient method to calculate the total isotropic sensitivity (TIS) of a mobile phone. The method is implemented by using the EM simulation, the digital signal modeling and the RF link budget simulation. By considering digital harmonic noise, the accuracy of the TIS calculation can be increased. Simulation results for the phone structure show the availability of this proposed...
A measurement method for verifying final conjugate match condition of assembled RFID tag is proposed in this paper. The verification results and maximum read range test results are all in good agreement. The verification method can be used to make sure whether the assembled RFID tag is in good match condition or not. In the future work, we will study how to use the verification method to find the...
The effects of hand positions on the mobile phone antenna performance in terms of OTA parameters and peak spatial SAR were studied with a commercial mobile phone model. Different hand positions cause significant change in both OTA performance and SAR values. It was also found that the hand phantom may have positive effect on the mobile phone antenna performance at GSM band. However, higher SAR value...
The aim of this paper is the study of some asymptotic properties and invariances of the electric field integral equation (EFIE) when applied to large and smooth structures. It is theoretical in nature, and thus no numerical results are included in this communication.
Many physical materials that we wish to interrogate with electromagnetic signals are conductive. Thus, we need to understand the propagation dynamics of electromagnetic pulses through dispersive, conductive materials. Closed-form solutions are preferable to numerical solutions in that they provide an explicit expression for the dependence of the propagated field on the physical parameters. Here, we...
In this paper, few topics related to the near-field and far-field behavior of a vertically oriented antenna above a PEC ground plane is discussed. The very near-field is determined by the position where the wave impedance approaches free space impedance, and the phase of the wave impedance approaches zero. As one move further ahead the wave sphericity condition determines the transition from the radiative...
A hybrid simulation of wideband polarimetric radar backscatter of humans within a building is introduced. The model is composed of a full-wave simulation tool that can accurately predict the scattering from a realistic human model, and an accurate indoor wave propagation and scattering model, known as bricktracer. These two models are efficiently connected using a Huygen's interface box that encloses...
This paper presents the design of a near-field reader and tag antennas in UHF that can be used for various smart shelves. The tag antenna is designed by introducing an ldquoSrdquo-shaped or ldquo+rdquo-shaped slot to the circular patch and the reader one is a rectangular slot array fed by a microstrip line. These antennas operated in UHF near-field are more reliable in many RFID applications where...
The retrieval of people trapped in buildings in fire or partially destroyed is a priority for rescue teams. Given the widespread use of mobile phones by the general public, an innovative idea to retrieve victims or to track rescue teams consists in capturing, via an antenna array acting as subrogated base station, the signals transmitted by cell phones (even if these are in idle mode). Real-time postprocessing...
A detailed analysis of the electric field integral equation (EFIE) at low frequencies is presented which is based on the Sobolev space mapping properties of the EFIE. The theory shows that in the low-frequency regime an EFIE with a logarithmic condition number growth can be obtained. This, provided that both the solenoidal and non-solenoidal parts of the EFIE are properly regularized. The regularization...
In a communication satellite, multiple frequency bands are used for transmitting and receiving communication, data and tracking signals. In this paper we present design, analysis and test results of a dual-aperture coaxial multiband feed horn. The coaxial configuration is particularly useful for the frequency bands that are widely separated. Our design goal was to operate at S-, Ku-, K- and Ka- bands...
The Expanded Very Large Array (EVLA) project is currently under way to upgrade the Very Large Array (VLA) to improve the sensitivity, bandwidth, spectral resolution and frequency coverage of the existing array of 27 radio telescopes. The EVLA receivers will provide continuous frequency coverage from 1 GHz to 50 GHz. Three of the cryogenically cooled EVLA receivers will provide octave band coverage...
Improving the connectedness of airliners in flight to allow the realisation of passengers' expectations for uninterrupted cell phone usage and internet access requires overcoming the bottleneck between the airliners' internal networks and the wider world in a cost effective manner while still providing sufficient bandwidth. The 43.5 - 47 GHz band is attractive for airliner to ground links due to lack...
This paper introduces a ray-tracing based channel model for 5 GHz which is the promising band for next generation wireless local area network (WLAN). WLAN technology is now becoming a viable alternative to traditional wired solutions even in the office environments. Moreover, the access point (AP) equipped with multiple-input-multiple-out (MIMO) antenna arrays have received great interest for high...
Scattering problems with multiple canonical scatterers, like cylinders and spheres, may be modeled by utilizing the orders-of-scattering approach. This method provides an exact solution; however, being iterative in nature, the accuracy of the solution depends on the number of iterations; in other words, the number of higher-order scattered fields taken into account. The orders-of-scattering solutions...
In this paper, we demonstrated that hallway propagation is driven by multiple wall reflections leading to high received field in both LoS case and non-LoS case at hallway junctions due to multiple corner diffraction. The result was verified by T-shaped hallway measurements. Based on the simulation results, it was shown that a repeater system with 30 dB total gain can enhance propagation around hallway...
In this paper, the compact slot array antenna using partial H-plane is presented. The design antenna has one quarter cross section compared with that of conventional waveguide slot antenna. To design the antenna, the numerical design method is described and the slot array antenna is designed in S-band. The design results confirm that proposed antenna satisfy the array antenna performance in spite...
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