Dalia Nashaat

Multiband and UWB V-Shaped Antenna Configuration for Wireless Communications Applications

A new configuration of multiband/ultra-wide-band (UWB) antenna is investigated. The antenna is a V-shaped patch with unequal arms coupled electromagnetically to single feed isosceles triangular PIFA thorough two unequal slots. The six multiband operations are achieved due to the different lengths and widths of the V-shaped patch as well as the two coupling slots. Two more modes can be added by loading the triangular planar inverted F-antenna (PIFA) with V-shaped slot. Wide bandwidth of 27% is achieved by simply adjusting the feeding point position, thus generating staggered resonating modes. UWB operation with 53% bandwidth can be achieved by folding the shorting wall of the triangular PIFA.

Multiband and miniaturized inset feed microstrip patch antenna using multiple spiral-shaped defect ground structure (DGS)

Microstrip patch antennas with inset feed have been studied extensively over the past two decades because of its practical advantage when used in mobile wireless systems. The length of MPA, however, is comparable to a half wavelength with single resonant frequency and bandwidth around 2%. In this paper, we describe a novel approach to reduce the antenna size and provide multiband operation. Electromagnetic bandgap (EBG) structure is used as defect ground plane structure to reduce size and achieve multiband resonant frequencies. Two cells of spiral-shaped defected ground structure (DGS) with each cell composed of spiral with four arms are used in the design. Simulation results show that more than 50% reduction in size was achieved as well as fives resonant frequencies resulted from the new design. One resonance resulted from the fundamental patch antenna while the other four resulted from each spiral arms. Acceptable E-plane and H-plane radiation patterns and an antenna gain of about 4dB are achieved.

Enhancement of ultra-wide bandwidth of microstrip monopole antenna by using metamaterial structures

As wireless communications applications continue to require more and more bandwidth, there has been continued increase in demand for ultra-wide bandwidth antennas. Planar monopole antennas are generally suitable for mobile applications and hence we researched avenues to improve the bandwidth of this antenna structure. First part in this paper describes the design of novel compact and ultra-wide bandwidth (UWB) antenna. The basis for achieving the UWB operation is through using semicircular microstrip monopole antenna with modified ground plane as semi circular patch like umbrella shape. This shape produced bandwidth ranging from 2 to 30 GHz with discontinuities from 7GHz to 10GHz, from 12.5 GHz to 17.5GHz and with a size reduction around 50% from conventional rectangular shape patch. Second part of this paper is focused on further improving in the antenna performance by using metamaterial structures such as Metallo-electromagnetic band gap structure (MEBG) and spiral artificial magnetic conductors (SAMC). The final novel antenna design provides an impedance bandwidth (S11≪-10dB) of more than 29GHz corresponding to over 900% increase over the original bandwidth.

Electromagnetic analyses and an equivalent circuit model of microstrip patch antenna with rectangular defected ground plane

This paper presents an investigation of both electromagnetic wave model and equivalent circuit model for microstrip patch antenna (MPA) with rectangular defected ground plane structure (RDGS). The objective of the proposed design is to reduce antenna size from Wi-Fi wireless band to the Bluetooth band. The first part of the paper describes the electromagnetic wave modeling using the High Frequency Structure Simulator (HFSS®) software to study the effect of RDGS on antenna resonant frequency. An optimization tool together with curve fitting were then used to formulate an approximate equation that describes the identified trends from the simulations. Second part is focused on estimating, using the Advanced Designing System (ADS) software the parameters of an equivalent circuit model for MPA with RDGS. The developed equivalent circuit consists of lumped elements for both MPA and RDGS structure and also include representation of the electrical and the magnetic coupling between rectangular grounded slot and MPA. Optimum values of the equivalent circuit elements were determined, and the overall simulation results were confirmed experimentally.

A wideband compact shorted rectangular microstrip patch antenna with U-shaped slot

In this paper, a wideband shorted microstrip rectangular patch antenna (SMRPA) is proposed for Bluetooth and wireless LAN applications. The wideband performance is achieved by inserting a U-shaped slot of unequal arms on the patch surface so that two adjacent resonant modes are exited. The designed antenna at 4.95 GHz has an overall length of /spl lambda//sub 0//4 with bandwidth of 24% and gain of 7.8 dB.