Introduction
With the advent of extensive space exploration and advancement of telecommunication, the technological development has swarmed the world in the very years. It is now a matter of seconds that a person from a remote part of the world can connect to another at the other part. In this way telecommunication has benefitted a great deal from a number of technological advances in antenna development. Henceforth, the present paper is a thorough investigation of advanced antenna technology. The paper investigates the issue at hand with an in-depth insight and also touches upon the existent research and future directions of the research in antenna technology. The paper discusses major developments in the antenna technology domain.
Background
It is the receiving and radiating of the electromagnetic waves that the devices called antenna are used for. In military operations and surveillance activities these devices have existed for quite a considerable time; similarly, at present, in the day-to-day life antennas are used for a number of diverse functions and activities such as commercial telecommunication; a number of telecommunication application like PCS and cellular find antenna as the major device for operation today.
To date, antennas are available in a variety of sized, shapes, and provide for a number of operations; their geometry is designed by the use of varying level of electromagnetic computational functions. At present, the available antenna technologies use superconducting and magnetic materials in forms of bulk and thin films in the process of antenna fabrication; these materials are also used in other devices and elements related to antenna such as switches, delay lines, filters, and so forth.
However, as the antenna sizes are getting smaller, it is observed that data loss is being reported because of electromagnetic dispersion that takes place in different materials used; this has a direct effect on the performance and also on the gain obtained or intended to obtain form current antenna technologies and devices. There are a number of reasons for data loss and reduction in gain. For instance, “In the area of mobile communications, material properties of filters used in the communications network directly govern the signal transmission and reception at base stations and mobile units” (Dtic.mil, p. 1, n.d.).
Moreover, commonly found problems are cross talks and traffic interference that are seen as the common of all problems that all cause in the loss of data materials. However, at very present, the research in the area of antenna technology has considerably increased that focuses on manufacturing small size smart antenna devices which uses phased-array technology; the designs of antennas are also under great scrutiny and today we see research developing sophisticated geometry designs so that improvement can be brought into the directivity of the signal. What has, none the less, not picked up increased pace in the domain of antenna research today is research and considerable development in the materials technology “that exhibit high frequency properties”.
Today, the critical areas that require attention and more research are lower losses, characteristic of tailored electromagnetic attraction, better matching of impedance, and betterment in the correlation properties of electromagnetic microstructure. Thus, the entire focus of research is expected to shirt toward nano-materials so that superior quality materials for much enhanced electromagnetic properties can be developed. (Dtic.mil, pp. 1-5, n.d.). In the upcoming section, some of the very latest areas of antenna technology are discussed in detail and with cross examination through different sources.
Multi-layer Microstrip Antennas
These are small antennas which are made by the use of printed microstrip technology. This technology has a number of advantages over traditional antenna devices such as parabolic reflections. The antennas manufactured by the use of microstrip technology are highly advanced devices as they provide a number of advantages as they can shape the host structure; they can be manufactured by conventional processes like circuit board; as well as these are highly well-matched with microwave technologies. These antennas can also be produced in bulk quantities so that cost can be lowered. A number of developmental steps have been taken to improve this technology, e.g., bandwidth has been enormously improved (Cuhaci, p. 1, 2008).
When it comes to research in the area of development of multi-layer microstrip antennas, it must be noted that the recent waves of insights have been majorly aroused by development in the technology of planar antenna and monolithic microwave integrated circuit (MMIC) antenna technologies. Thus today more attention is being paid in the enhancement of planar circuits and their designs. However, it is evident that this domain faces considerable hindrances when it comes to clearer insight and understanding of a number of issues present in multi-layer microstrip antennas (Kaddour, et al. pp. 1-7, 2003).
Studies on antenna technologies reveal that still there are ways in which more improvement with regard to cost-cutting conditions and performance can be given a material status. The focus on multi-layer microstrip antennas research also suggests that commonly found devices are multiresonant that have globally tuned frequencies; however, these antennas cannot be right driven to enhance radiation of the same frequency.
As such, the focus is also shifting into these directions so that a multi-mode antenna can become reality which focuses to bring in one design two or more than two types of antenna for diversified operations. However, there at play is the incorporation of two or more than two antenna modes into one input feed which is controlled by better mechanism to better operate the combined pattern of radiation. This technology as developed today is known as Coupled multilayer microstrip antenna (Patent Storm, p. 1, 2004).
Dielectric Resonator Antennas (DRA)
Dielectric resonator antenna (DRA) is another advanced antenna technology developed and enhanced to meet a number of future and present needs and operational functions. This technology basically provides alternative to microstrip antenna technology and carries many other advantages with it like it makes loss much lower; this antenna provides wider bandwidth and has enlarged flexibility of design.
The materials used to manufacture the DRAs are fabricated from materials which are low-loss dielectric materials; these antennas are generally installed on ground planes. The characteristics of their radiation and the patterns of radiation are triggered within the DRA in the mode of operation. A number of different feed mechanisms can be used with these antennas to excite these modes; some of them are microstrip, probe, and slot.
The designs of these antennas can be used to produce two types of polarization. One is linear polarization, whose polarization is at low-cross; the other is circular polarization. The latter polarization if operated with a wider frequency bandwidth can give good results. In antennas arrays, DRAs can be taken as elements so that low-loss and high-gain applications can be operated via DRAs. DRAs are compatible with various types of printed antenna technologies. With regard to fabrication tolerance, this technology is less sensitive. Research to enhance this technology is moving toward a number of directions specifically in developing the DRAs arrays and the enhancement of the bandwidth (Rocha, et al., p. 1, n.d.)
The popularity of DRAs is also due to the multiple shapes of small sizes and light weight. This technology is receiving more acceptance of use because it offers wider bandwidth than that of in other antennas like microstrip. Because this technology has a surface signal excitation, it fairly easily avoids disadvantages which are considered as inhered in, say, microstrip antennas. Moreover, this technology also has safe operation moving over to the loss that happens in high conduction. “It has been shown that DRA can be excited by a coaxial probe, a microstrip transmission line, aperture coupling or a co-planar waveguide (CPW) feed”.
When it comes to further research into the same technology, it is revealed that hemispherical DRA antennas have an edge over other DRA shapes. It is very easy to fabricate this shape (hemispherical DRA); as well as, this very shape can be easily analyzed due to the fact that it does not have edges (Abdulla, et al., p. 1, n.d.). First known to be functional in the late 1980s DRAs are expected to hold more market in the future due to a number of advantage discussed above (Patents online, p. 1, n.d.).
Lens Antennas
Popular for the past as long as 50 years, lens antenna technology is also moving toward upward curve of advanced development in the arena of telecommunication. The properties of these antennas are basically linked to the fact that “between two metallic plates parallel to the electric vector, the phase velocity of electromagnetic waves is greater than in the air, thus creating a medium with an index of refraction less than one”. There are a number of advantages that these antennas carry over other antenna like reflector antennas. This feature alone makes these antennas more attractive for aerospace operations and applications.
Major applications are radars and Earth Observation. The more prominent advantage of this technology is that its lens system provides wide-angle scan which offers a huge number of technical advantages with this device that range from gain in radiation pattern to lens performance in the longer run both in terms of quality and enhanced results. The waveguide lens antennas give a better option as opposed to that of parabolic reflectors. These antennas also have a much wider range of scanning that can be anywhere from 60o to 100o. They also provide more tolerance when it comes to inaccuracies in dimensional functions and operations.
These antennas can also be mounted in an axial way so that their rotation is much more perfect and up to that mark (Hamidi, p. 1, 2001). With this technology it is also possible to convert microwave energy (which is spherically radiated) into a wave which is plane; however, this change occurs only in a given direction. This happens when a wave source is used with collimating lens (Integrated Publishing, p. 1, n.d.). Although there are quite a few technologies within this antenna (such as Fresnel lenses and dialectic lenses), the metal-plate lens antenna has a clear edge over others because it is the easiest to construct and also the lightest-weight to carry (Wade, p. 1, 1998).
Reflectarray antennas
Reflectarray antennas were invented more than 40 years ago. However, it is only recently that this technology has received wider commercial interest due to a number of feasible factors. It is also important to note that at present this technology has not been thoroughly examined when it comes to empirical investigation. As such there is still more effort required with regard to comprehensive understanding of the technology for better results. It is only very recently that some comprehensive studies have been done (Huang & Enciner, p. 1, 2007). A reflectarray antenna has a low status in the range of reflector.
It consists of an array of elements which are from the patch of microstrip. This technology also has a feed which illuminates it. This antenna, however, has its own unique market and operational features which are perhaps not found in any other antenna technology. These features, then, make this technology one of the best to use. This antenna can be used with conventional reflectors; being flat and not so high-costing, they are easy to construct as well as their manufacturing is also cost-effective and easy. Adaptable to different mounting surface heights, these antennas can be fixed to point their beam into a fixed but large angle which is up to 60o.
Equally important to note as the salient feature of this technology is that because of its beam direction and feeding of space “the complexity and the losses of a microstrip feed network” can be eliminated. In addition to these features, there are other attractive applications that make this technology feasible for a number of operations. The concept of this technology basically emerges from the idea of “the scattering properties of microstrip patches”.
Electromagnetic energy is radiated by the elements which are printed on the surface essentially reflective. This radiation, then, is streamlined into a prearranged beam which moves into a prescribed direction. The main beam expelled by this antenna (another advantage to note), it can then be analyzed electronically which gives it an edge over other antennas used for similar operations.
There are quite a few methods that have been suggested and discussed in the literature of antenna technology. However, at present research is being directed as to how the reflectarray beam can be steered more dexterously so that more advantage of this technology can be obtained (Boccia, et al., p. 1, n.d.). Another prominent feature of this antenna technology is that it provides 360 degree tuning of signals which are reflected and this is continuously taking place. The maximum loss is just at 5.4 GHZ. Research suggests that with proper operation its beam can be steered more dynamically which gives the advantage over other broadband antennas (Friedrich, p. 1, 2007).
Works Cited
Abdulla, P. & et al. (n.d.). Coplanar waveguide-fed slot-coupled hemispherical dielectric resonator antenna. Indian Institute of Technology. Web.
Boccia, et al. (n.d.). A varactor loaded reflectarray antenna. Universita della Calabria. Web.
Cuhaci, M. (2008). Avanced antenna technology. Communications Research Centre Canada. Web.
Dtic.mil, (n.d.). Advanced nano-materials for antenna application. Advanced materials Research Institute, University of New Orleans. Web.
Friedrich, N. (2007). Reflectarray antenna can steer main beam to large angles from broadside. Web.
Hamidi, M., & et al. (2001). Deployable RF lens antennas. One Space Park, Redondo Beach, CA. Web.
Huang, J., & Enciner, J. A. (2007). Reflectarray antenna. Web.
Integrated Publishing, (n.d.). Lens antennas. Electrical engineering training series. Web.
Kaddour, M., Mani, A., Charsallh, A., Gharbi, A., & Baudrand, H. (2003). Analysis of multilayer microstrip antennas by using interative method. Journal of Microwaves and Optoelectronics,3,(1), pp. 1-7.
Patent Storm (2004). Coupled multilayer microstrip antenna. Web.
Patents online (n.d.). Dielectric resonator antenna. United States Patents. Web.
Rocha, H. H. B. & et al., (n.d.). The bandwidth enhancement of dielectric resonator antennas. Universidade Federal do Ceara. Web.
Wade, P. (1998). Metal-plate lens antennas. Web.