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

The reduction of Specific Absorption Rate (SAR) with metamaterial is performed by the finite-difference time-domain method (FDTD) with Lossy-Drude model by CST Microwave Studio in this paper. The metamaterials can be achieved by arranging split ring resonators (SRRS) periodically. The SAR value has been observed by varying the distances between head model to phone model, different width, different thickness, and different height of metamaterial design. Metamaterial has achieved 42.12% reduction of the initial SAR value. These results can endow with supportive information in designing the wireless communications equipments for safety compliance.

https://www.jstage.jst.go.jp/article/elex/7/4/7_4_240/_pdf

Study of Specific Absorption Rate (SAR) in the human head by metamaterial attachment

A planar monopole antenna for UWB applications

A dual polarized microstrip patch antenna is proposed for Ku-band applications. The corner chopped square patch with four bent slots is adopted in this design. The antenna has a compact structure and the total size is 15 mm × 15 mm. The result shows that the impedance bandwidth (VSWR ≤ 2) of the proposed antenna is 950 MHz (7.76%). The antenna with reduced size is also able to achieve the stable radiation performance with a maximum gain of 7.6 dBi in the operating band of 11.76 GHz to 12.71 GHz and the gain variation is about 0.8 dBi. The present design provides a maximum of -26 dB isolation level between the two ports and a stable low cross polarization level for both Eand H-planes. Details of the proposed antenna design and results are presented and discussed. The patch shows a high matching level in Ku-band and isolation elements that makes it suitable for wireless and satellite communication. Dvojno polarizirana mikrostrip antena za Ku-frekvenčni pas Kjučne besede: dvojna polarizacija, mikrotrakasta antena, Ku-frekvenčni pas, visoka izolacija Izvleček: V prispevku opišemo mikrotrakasto anteno z dvojno polarizacijo za uporabo na Ku-frekvenčnem pasu. Antena ima kompaktno strukturo in je velika 15 mm x 15 mm. Rezultati kažejo pasovno širino ( VSWR ≤ 2) 950 MHz (7.76%). Tako zmanjšana antena zmore stabilno sevanje z maksimalno ojačitvijo 7.6 dBi znotraj pasovne širine med 11.76 GHz do 12.71 GHz in stabilnostjo ojačitve znotraj 0.8 dBi. Trenutna zasnova omogoča maksimalno izolacijo med stopnjama -26dB in stabilno nizko križno polarizacijo med E in H ravnijo. V članku so opisane podrobnosti in rezultati predlagane zasnove antene.

Dual polarized microstrip patch antenna for Ku-band application

A compact planar antenna operating at a frequency range of 3–16 GHz is presented for wideband applications. The antenna is composed of a square patch fed by a microstrip line and a partial ground plane with a rectangular slot. The proposed antenna is very easy to be integrated with microwave circuitry for low manufacturing cost. The flat antenna has a compact structure and the total size is 29 mm × 22 mm. The result shows that the measured impedance bandwidth (VSWR≤ 2) of the proposed antenna is 3.2–15.44 GHz, with a notch from 4.7 to 5.8 GHz. The effects of the structure parameters on impedance bandwidth are also investigated. Details of the proposed compact planar antenna design are presented and discussed.

Printed Planar Antenna for Wideband Applications

The design of a compact metamaterial ultra-wideband (UWB) antenna with a goal towards application in microwave imaging systems for detecting unwanted cells in human tissue, such as in cases of breast cancer, heart failure and brain stroke detection is proposed. This proposed UWB antenna is made of four metamaterial unit cells, where each cell is an integration of a modified split ring resonator (SRR), capacitive loaded strip (CLS) and wire, to attain a design layout that simultaneously exhibits both a negative magnetic permeability and a negative electrical permittivity. This design results in an astonishing negative refractive index that enables amplification of the radiated power of this reported antenna, and therefore, high antenna performance. A low-cost FR4 substrate material is used to design and print this reported antenna, and has the following characteristics: thickness of 1.6 mm, relative permeability of one, relative permittivity of 4.60 and loss tangent of 0.02. The overall antenna size is 19.36 mm × 27.72 mm × 1.6 mm where the electrical dimension is 0.20 λ × 0.28 λ × 0.016 λ at the 3.05 GHz lower frequency band. Voltage Standing Wave Ratio (VSWR) measurements have illustrated that this antenna exhibits an impedance bandwidth from 3.05 GHz to more than 15 GHz for VSWR < 2 with an average gain of 4.38 dBi throughout the operating frequency band. The simulations (both HFSS and computer simulation technology (CST)) and the measurements are in high agreement. A high correlation factor and the capability of detecting tumour simulants confirm that this reported UWB antenna can be used as an imaging sensor.

/pdf/microwave-imaging-sensor-using-compact-metamaterial-uwb-2c4ewljaua.pdf

Norbahiah Misran

Papers

Study of Specific Absorption Rate (SAR) in the human head by metamaterial attachment

A planar monopole antenna for UWB applications

Dual polarized microstrip patch antenna for Ku-band application

Printed Planar Antenna for Wideband Applications

Microwave Imaging Sensor Using Compact Metamaterial UWB Antenna with a High Correlation Factor