The Anomalous Refraction in Photonic Band Gap Materials at Microwave Frequencies (Research Paper Sample)

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The Anomalous Refraction in Photonic Band Gap Materials at Microwave Frequencies: Application to Antennas
Abstract
This research paper intends to widely cover on refraction in photonic Band Gap Materials at microwave frequencies more so in relation to Antennas application. Photonic crystals (Band Gap Materials) are simply metallic or periodic dielectric configurations comprising of photonic bands in correlation to semiconductors’ electronic bands. In the current world of researchers and scholars, studies have proven existence of numerous applications of photonic crystals in diverse fields. However this paper intends to concentrate on one particular application, the antennas, under microwave frequencies. This will be justified with respect to its possibilities, which is simply doping of photonic semiconductors resulting to macro electromagnetic frequencies. This paper will equally conduct a setup for identifying the radiation prototypes of a given antenna at diverse angles.
Definitions
Photonics: knowledge and study of molding the streaming of light
Photonic Crystal: A material which is non-light-absorbent and entails a refractive index which can display intervallic inflection in not less than two orthogonal paths
Band Gap- A variety of energies or frequencies with the absence of disseminating modes of a wave
Light Localization: A condition in which a ray of light at a given rate is entirely shut in to a small, limited region and can in no way disseminate away but thorough given nonlinear interface
PBG material: non-light-absorbent which comprises a bad gap for EM waves circulating in all directions
1 Introduction
Nearly two decades ago, it was discovered that a synthetically generated periodic structure would produce a stop band for electromagnetic waves, where the waves’ transmission were subdued in a given array of frequencies in all directions (Yablonovitch 2059). In semiconductors (with reference to electronic band gaps) such configurations are referred to as photonic crystals or photonic band gap (PBG) components, as stipulated by John (58). Ancient applications of these photonic crystals were however technologically challenged to microwave frequencies and millimeter wave frequencies. This limitation led to further research and study on the same until feasibility of single-mode LED s semiconductor lasers came into existence (Gourley et al 687). Another imperative facet of photonic crystals is that, equal to acceptor or donor forms in an electronic crystal, getting rid of the crystal’s periodicity brings forth localization of the electromagnetic field surrounding the defect volume. Hence, it is through such properties that these photonic crystals are employed in manipulating the behavior of light; resulting to numerous applications, unto which our study topic is based.
1.0Microwave Photonic applications on Antennas
Other than on Antennas, there are a number of other applications of PGB (Photonic Band Gap) materials more so within millimeter-wave and microwave distinct, such as Bluetooth technology, GPS, scanned arrays, and mobile telephony (Hurtado et al 28). Satellites with low earth trajectory are employed to deliver super data-rate broadcast for multimedia uses. Such purposes necessitate scanned multi-beam antennas comprising of a wide bandwidth. With the generation of personal communication expertise, antennas (Wearable) have embraced much interest. A number of wearable antennas applications can be realized, for instance miniature remote cameras and radio tagging. Therefore, antennas do engage a very fundamental role in the best possible design of hand-held or wearable units employed in such services. Practically, an essential factor worth consideration during design of these antennas is the EM (electromagnetic) interaction among the wearable unit, the antenna and the operator (human being).
1.1 Microwave PBG Antennas and gears
Research has provided that a given range of antenna configurations can be realized using electromagnetic band gap (Luo 65). Going by a few of such configurations, its worth mentioning slot antennas, dipole antennas, resonant cavity antennas (superstrate antennas), parabolic reflector antennas, spiral and curl antennas, bow-tie antennas patch antennas, or/and a permutation of the mentioned.
1.1.1 The patch antenna
One popular configuration at microwave frequencies is the patch antenna. This is so due to its characteristics such as robustness, inexpensive (during manufacture), and conformability. However, there is a single limitation to this configuration: probable excitation of surface waves, which can bring about dilapidation of radiation pattern, poor efficiency, decrease in gain, and boost in mutual coupling. Surface waves can be subjected to dominancy if high dielectric steady substrates are engaged, for instance those employed in MMIC RF configuration. Equally enough, dominancy can be experienced upon increment of substrate thickness for a greater bandwidth.
For patch antennas, it has been proven that PBG substrates drastically reduce the impact of exterior waves as frequency function, and are capable of facilitating moderate broadband frequency performance, as shown in figure (a) below (Gonzalo 22).
Figure a. determined radiation patterns from 14 to 16 GHz of 0.25GHz each for the H plane for patch antenna
1.1.2 Resonant cavity antennas
There is a slight disparity that resonant antennas have with respect to patch antennas. Patch antennas work in the hub of the band gap, whereas resonant cavity antennas function at the edges of the band gap. This enhances utilization of the ideology that there exists an angular reliance of the conduction curves. However, apart from transmission at normal incidence, momentous attenuation of full transmission is encountered for other angles (Enoch 2002). The outcome is a vastly directive pattern of radiation, having perfect rotation pattern proportion, however a narrowband operation. On the whole, these are made employing a ground plane beneath a feeding supply (slot, patch, wire), whereas a resonator cavity is created by use of EBG material, for instance the superstrate.
1.1.3Highly Directional Resonant Antennas
A photonic crystal-base...