Mohamed Sanad

Double C-patch antennas having different aperture shapes

Double C-patch antennas having different aperture shapes are experimentally investigated and reported. The effect of different design parameters on the performance of the antenna is studied and presented. The advantages of such antennas over the conventional rectangular microstrip antennas are explained.

A compact dual-broadband microstrip antenna having both stacked and planar parasitic elements

It is possible for a single-element microstrip antenna to operate at two frequencies corresponding to two various resonant modes. The separation between the two frequency bands could be altered by placing shorting pins at the proper locations on the nodal lines of the fields of one of the modes. If both frequency bands are required to be too close to each other, at least, two patches have to be used simply by stacking them together. Using any of the above techniques, two separate narrow frequency bands may be obtained. However, in some antenna applications, the antenna is required to operate at two separate frequency broadbands. A very important example of such applications is the antenna used in cellular phones. Using a dual-band antenna having two separate bands, helps in eliminating the lossy expensive duplexer or at least making it cheaper and easier to design especially if two separate feeds could be used. A compact microstrip antenna has been developed for such an application. It consists of a driven element and five small parasitic patches distributed in two stacked layers. The two layers have similar geometries and their dimensions are almost equal.

Microstrip antennas on very small ground planes for portable communication systems

A limited number of investigations have been reported in the literature about microstrip antennas on small size ground planes. That is because a complete theoretical analysis of an arbitrary shaped microstrip antenna on a substrate of finite dimensions is a difficult task, and no single approach can be conveniently used for the accurate prediction of the radiation patterns. However, most of the investigated sizes of the truncated ground planes are still relatively large. In this paper, the effect of the size of the ground plane on the radiation patterns of the microstrip antenna was studied experimentally, where very small sizes of ground planes were considered. In this study, only rectangular microstrip antennas were investigated because most portable equipment boxes are rectangular in shape.<<ETX>>

Effect of the human body on microstrip antennas

The purpose of the paper is to study the effect of the human body on different configurations of microstrip antennas and the parameters that may control this effect. Unfortunately, there is no accurate model to simulate the human body especially at high frequencies. Therefore, all results in the research are experimental. To measure the effect of the human body on the performance of any microstrip antenna in the anechoic chamber, the author stands on the turn table behind the ground plane of the antenna and puts his hands as close as possible to the antenna in front of its radiation side without touching it. In these measurements only rectangular microstrip antenna configurations were considered. This is because most portable equipment boxes have a rectangular shape and a built-in antenna may follow the inner shape of the box.<<ETX>>

A wide band microstrip antenna for portable cordless telephones

The microstrip antenna is one of the most preferable for small portable digital cordless telephones, especially when a built-in antenna is required. Most portable cordless telephones require the antenna to have an impedance bandwidth of at least, 3 or 4 % at 900 MHz. A very compact wide band microstrip antenna is presented where both the driven and the parasitic elements are partially shorted double C-patches on a very small ground plane.

A resonant handset antenna that can cover all bands of UHF mobile TV, GSM and CDMA without using matching circuits

Antennas for mobile digital TV are required to have a very wide frequency band. For example, UHF DVB-H is designed to work in the frequency band from 470 MHz to 862 MHz. This is a very wide bandwidth which is difficult to cover with a single resonant antenna. Therefore, matching circuits are usually used to tune the antenna for this band [1]-[3]. Matching circuits increase the complexity, the size and the costs of the antenna and also reduce its efficiency. On the other hand, the mobile TV band overlaps with the CDMA/GSM800 band (824–894 MHz) and it is also too close to the E-GSM900 band (880–960 MHz). This overlapping may cause severe interference between the antennas of these applications especially if they were placed close to each other inside the handset. A novel solution to overcome all these problems is to use only one wideband resonant antenna that can cover all bands of UHF mobile digital TV, 700 MHz WiMax (698–806 MHz), CDMA, GSM800 and E-GSM900.

Non-planar shorted double C-patch antennas for portable communication equipment

Rectangular, circular and ring microstrip antennas on cylindrical, spherical or conical surfaces have been studied by many authors. However, in these studies, only open circuit, half-wavelength, conventional microstrip antenna geometries have been considered. In this paper, non-planar shorted and partially shorted double C-patch antennas [Sanad, 1995] with and without parasitic elements have been studied experimentally.

Novel Wideband MIMO Antennas That Can Cover the Whole LTE Spectrum in Handsets and Portable Computers

A dual resonant antenna configuration is developed for multistandard multifunction mobile handsets and portable computers. Only two wideband resonant antennas can cover most of the LTE spectrums in portable communication equipment. The bandwidth that can be covered by each antenna exceeds 70% without using any matching or tuning circuits, with efficiencies that reach 80%. Thus, a dual configuration of them is capable of covering up to 39 LTE (4G) bands besides the existing 2G and 3G bands. 2 × 2 MIMO configurations have been also developed for the two wideband antennas with a maximum isolation and a minimum correlation coefficient between the primary and the diversity antennas.

Low-Interference Dual Resonant Antenna Configurations for Multistandard Multifunction Handsets and Portable Computers

Low-interference dual resonant antenna configurations are developed for multistandard multifunction mobile handsets and portable computers. Only two wideband resonant antennas can cover most of the important wireless applications in portable communication equipment. The frequency bands of the dual antenna configuration can be adjusted according to the wireless applications that are required to be covered. The bandwidth that can be covered by each antenna is about 80% without using matching or tuning circuits. Three sample dual antenna configurations with different frequency bands are presented. The interference between the low-band and high-band antennas of these three configurations is investigated, and the ways of reducing this interference are studied. The most effective factor on the interference between the low-band and high-band antennas is their relative orientations. When the low-band and high-band antennas of each configuration are perpendicular to each other, the isolation between them significantly increases. This eliminates the need for any special tools or techniques to suppress the mutual coupling between them. The new antennas have very small cross-sectional areas, and they are made of a flexible material. They do not require any additional components or ground planes. They can be used as internal, external, or partially internal and partially external antennas.

A Novel Internal Dual-Polarized EBG Antenna for Indoor Reception of UHF Terrestrial Digital TV Broadcasting

A novel internal antenna has been developed for indoor reception of UHF terrestrial digital TV broadcasting. The overall size of some configurations of the new antenna is less than 2 cm3, and its weight is less than 1 gm. It is made of a flexible material that can be bent or folded and shaped in any form. It is an unbalanced resonant antenna that does not need a matching circuit. The new antenna can be fully embedded inside TV sets or portable computers. It has a bandwidth of about 68%. Thus, it can also cover the bands of GSM and CDMA, which is advantageous in case of portable computers. The new antenna is linearly polarized. It can be easily modified to be dual polarized by combining two orthogonal antennas with one or two feed points. The overall efficiency of some configurations of the new indoor digital TV receiving antenna is more than 80%, and its peak gain is about 2 dBi over the whole UHF band. The peak gain can be increased to more than 5 dBi by adding EBG (electromagnetic bandgap) structures. The EBG structure also increases the efficiency to around 90%.