The term photonic crystals appears because of the analogy between electron waves in crystals and the light waves in artificial periodic dielectric structures. During the recent years the investigation of one-, two-and three-dimensional periodic structures has attracted a widespread attention of the world optics community because of great potentiality of such structures in advanced applied optical fields. The interest in periodic structures has been stimulated by the fast development of semiconductor technology that now allows the fabrication of artificial structures, whose period is comparable with the wavelength of light in the visible and infrared ranges.

http://ieeexplore.ieee.org/iel5/6354/16969/00781867.pdf

Photonic crystals

Electromagnetic Metamaterials: Transmission Line Theory and Microwave Applications. By Christophe Caloz and Tatsuo Itoh.

Space-Time Block Coding for Wireless Communications

In general, Micropower Impulse Radar (MIR) depends on Ultra-Wideband (UWB) transmission systems. UWB technology can supply innovative new systems and products that have an obvious value for radar and communications uses. Important applications include bridge-deck inspection systems, ground penetrating radar, mine detection, and precise distance resolution for such things as liquid level measurement. Most of these UWB inspection and measurement methods have some unique qualities, which need to be pursued. Therefore, in considering changes to Part 15 the FCC needs to take into account the unique features of UWB technology. MIR is applicable to two general types of UWB systems: radar systems and communications systems. Currently LLNL and its licensees are focusing on radar or radar type systems. LLNL is evaluating MIR for specialized communication systems. MIR is a relatively low power technology. Therefore, MIR systems seem to have a low potential for causing harmful interference to other users of the spectrum since the transmitted signal is spread over a wide bandwidth, which results in a relatively low spectral power density.

/pdf/response-to-fcc-98-208-notice-of-inquiry-in-the-matter-of-3attixctl7.pdf

Response to FCC 98-208 notice of inquiry in the matter of revision of part 15 of the commission's rules regarding ultra-wideband transmission systems

We present a flexible, compact antenna system intended for telemedicine applications. The design is based on an M-shaped printed monopole antenna operating in the Industrial, Scientific, and Medical (ISM) 2.45 GHz band integrated with a miniaturized slotted Jerusalem Cross (JC) Artificial Magnetic Conductor (AMC) ground plane. The AMC ground plane is utilized to isolate the user's body from undesired electromagnetic radiation in addition to minimizing the antenna's impedance mismatch caused by the proximity to human tissues. Specific Absorption Rate (SAR) is analyzed using a numerical human body model (HUGO) to assess the feasibility of the proposed design. The antenna expresses 18% impedance bandwidth; moreover, the inclusion of the AMC ground plane increases the front to back ratio by 8 dB, provides 3.7 dB increase in gain, in addition to 64% reduction in SAR. Experimental and numerical results show that the radiation characteristics, impedance matching, and SAR values of the proposed design are significantly improved compared to conventional monopole and dipole antennas. Furthermore, it offers a compact and flexible solution which makes it a good candidate for the wearable telemedicine application.

Flexible and Compact AMC Based Antenna for Telemedicine Applications

There is an increasing demand for newer microwave and millimeter-wave systems to meet the emerging telecommunication challenges with respect to size, performance and cost. Microstrip antennas offer the advantages of thin profile, light weight, low cost, ease of fabrication and compatibility with integrated circuitry. This paper presents a coaxilly-fed single-layer compact microstrip patch antenna for achieving dual-polarized radiation suitable for applications in the IEEE Radar Band C and X. Simultaneous use of both frequencies should dramatically improve data collection and knowledge of the targets in an airborne synthetic aperture radar system. The designed antenna consists of three rectangular patches which are overlapped along their diagonals. The design and simulation of the antenna were performed using 3D full wave electromagnetic simulator IE3D. The antenna with a bandwidth of VSWR<2 reaches 154MHz (f0=6.83GHz) and 209MHz (f0=9.73GHz) was designed and simulated successfully.

Compact dual-band dual-polarized microstrip patch antenna for synthetic aperture radar

This paper presents an analysis of simple dual elements reconfigurable reflectarray unit cell with varying width of 2.0, 2.5 and 3.0 mm of its square ring against capacitive loading effect of a varactor diode from 0.4 pF to 1.3 pF. The operating frequencies intended is in the range of 8.0 to 8.4 GHz for remote sensing satellite data receiving antenna. Analysis is done by using Floquet mode approach in CST commercial software. The objective is to compare and determine an optimum performance of unit cell's reflection coefficient magnitude and phase range. It is demonstrated that at the operating frequencies of 8.0 GHz and 8.2 GHz, unit cell's phase range significantly improved from 107° and 191° to 305° and 294° respectively with width enlargement from 2.0 mm to 3.0 mm. At 8.4 GHz, it fluctuates at around 240° up to 280° concurrent with width enlargement. The reflection coefficient showed a minimum of −3.95 dB and maximum of −8.34 dB at center frequency in a tradeoff of improved phase range of the unit cell.

Capacitive Loading Effect of Dual Element Reconfigurable Reflectarray Unit Cell

A single-layer linearly polarized reflectarray element namely Concentric Circle Square Ring (CCSR) for Ku-band is presented in this paper. The adjustment of the reflected phase of the reflectarray element via variable capacitive loading which is realised by connecting the two rings with varactor diode. By using the full-wave EM field simulator-CST, simulation of the single element to perform exact measurement in standard waveguide were obtained. The measurement indicates that the element with attachment of varactor diode has good capability of changing the reflection phase between 0 to 20 V suppliede to the diode.

Capacitive loading radiating element for reconfigurable reflectarray at Ku-band

The reducing specific absorption rate (SAR) with metamaterials attachment is investigated in this paper. The finite-difference time-domain method with lossy-Drude model is adopted in this analysis. The technique of SAR reduction is discussed and the effects of attaching location, distance, and size of metamaterials, perfect electric conductor (PEC), and materials on the SAR reduction are investigated. Metamaterials have achieved a 41.47% reduction of the initial SAR value for the case of 1 gm SAR. These results suggest a guideline to choose various types of metamaterials with the maximum SAR reducing effect for a phone model. Vpliv dodatka metamateriala na absorpcijo EM valovanja v cloveski glavi Kjucne besede: antena, model cloveske glave, lossy-Drude model, metamateriali, specificna absorbcijska stopnja (SAR) Izvlecek: v clanku opisemo zmanjsanje parametra SAR ( specificna absorbcijska stopnja ) z dodatkom metamateriala. Analizo smo opravili z modelom Drude in uporabo koncnih diferenc v casovni domeni. Opisana je tehnika zmanjsanja parametra SAR , raziskani so vpliv lokacije, oddaljenosti in velikosti metamaterialov ter vpliv popolnega elektricnega prevodnika (PEC) in vrste metamaterialov na zmanjsanje SAR. Z uporabo metamaterialov smo dosegli 41,47 % zmanjsanje zacetne vrednosti SAR, ki je bila 1gm SAR. Ti rezultati pomenijo neko vrsto smernic za izbiro materialov za mobilne telefone, ki najbolj zmanjsujejo parameter SAR.

/pdf/analysis-of-metamaterial-attachment-for-em-absorption-in-5bm5vwrqne.pdf

Analysis of metamaterial attachment for em absorption in human head

In this paper, an S-band three-dimensional antenna for small satellite application has been presented. Folding the radiating element, use of shorting wall and ground reflector etc. different optimization techniques have been obtained to achieve a desirable performance from the antenna. Finally, the proposed antenna successfully obtained operating bands at 2–2.27 GHz and 2.53–3.58 GHz. The peak gain of the antenna is up to 4dB. The simple design structure make the antenna easily fabricable for mass production from a single copper sheet using stamping metal sheet method or 3D printing technology. The design and analysis of the antenna have been performed using electromagnetic simulation software. S band operation, directional radiation property, up to 4dB realized gain over the operating frequency make the antenna a candidate to be applied for communication system in small satellites.

Norbahiah Misran

Papers

Compact dual-band dual-polarized microstrip patch antenna for synthetic aperture radar

Capacitive Loading Effect of Dual Element Reconfigurable Reflectarray Unit Cell

Capacitive loading radiating element for reconfigurable reflectarray at Ku-band

Analysis of metamaterial attachment for em absorption in human head

A 3D directional antenna for S band small satellite communication system