In this letter, we present a novel printed monopole antenna for ultrawideband (UWB) applications. The proposed antenna consists of a square radiating patch with two rectangular slots and a ground plane with inverted T-shaped notch, which provides a wide usable fractional bandwidth of more than 120% (3.1212.73 GHz). The proposed antenna is simple and small in size. Simulated and experimental results obtained for this antenna show that it exhibits good radiation behavior within the UWB frequency range.

This letter presents an efficient technique to reduce the mutual coupling between two 5.2-GHz probe-fed patch antennas in an array format. Two different designs of folded split-ring resonators (FSRRs), composed of single and double rows, etched into the ground plane are proposed for more reduction of the mutual coupling and spacing between antennas. Parametric studies show that by carefully adjusting the basic design parameters, and so equivalent capacitance and inductance of the FSRRs, a reduction of more than 30 dB in the mutual coupling between two antennas with a very close distance of about 0.039 λ₀ (edge-to-edge distance) and 0.27 λ₀ (center-to-center distance) can be obtained. Measured S₂₁ of the array in the first and second designs of the FSRRs are about -56 and -45 dB, respectively. The features including very small occupied area, high performance, and noncomplex structure make the proposed FSRRs more useful for various related applications.

This letter presents a new design for a circularly polarized square slot antenna (CPSSA). The proposed single-layer antenna composed of a square ground plane embedded with two unequal-size inverted-L strips around two opposite corners is capable of generating a resonant mode for exciting two orthogonal E vectors. In this model, compared to the previous CPSSA structures, the impedance bandwidth and the axial ratio bandwidth of antenna are increased, which is four times wider than the impedance bandwidth of previous similar designs. The designed CPSS antenna with size 60 × 60 × 0.8 mm³ operates over the frequency band between 2.67 and 13 GHz (4.74:1, 132%) for VSWR <; 2, exhibiting a 32.2% (4.9-6.9 GHz, 1.5:1) circular polarization (CP) bandwidth. Throughout this letter, the improvement process of the axial ratio (AR) and S\\ properties are presented and discussed in detail.

A dual band-notched printed ultrawideband monopole antenna is presented, with a modified ground plane. By using this modified element including a pair of variable L-shaped slots, cut in the ground plane, additional resonances are excited and hence the bandwidth is increased up to 130%. To generate single and dual band-notched characteristics, we use inverted U- and fork-shaped parasitic structures, respectively, instead of changing the patch or feedline shapes. By properly adjusting the dimensions of these capacitive-coupled elements, not only one or two controllable notch resonances are achieved, but also the lower-edge frequency of the band is decreased. The measured results show that the proposed dual band-notched monopole antenna offers a very wide bandwidth from 2.2 to 13.4 GHz (143%), defined by 10-dB return loss, with two notched bands, covering all the 5.2/5.8-GHz WLAN, 3.5/5.5-GHz WiMax and 4-GHz C bands. Impedance, radiation, efficiency and gain characteristics of the antenna are also discussed.

This paper presents a novel modified Printed Tapered Monopole Antenna (PTMA)for ultra wideband (UWB)wireless communication applications. The proposed antenna consists of a truncated ground plane and two-tapered radiating patch separated by a slot (air gap)of different slopes, which provides a wideband behavior and relatively good matching. Moreover, the effects of a modified T-shaped slot inserted in the first tapered patch, on the impedance matching is investigated. The antenna has a small area of 23 × 26. 5m m2 and offers an impedance bandwidth as high as 100% at a centre frequency of 7.2 GHz for S11 < −10 dB, which has an area reduction of 15% and a frequency bandwidth increment of 72% with respect to the previous similar antenna. The presented antenna covers the 5.2/5.8 GHz WLAN and 5.5 GHz WIMAX operating bands. Numerical analysis using Ansoft HFSS and measurement results is also presented in the paper.

Using microwave energy for medical applications has been considered a long time ago. By introducing near-field focused array antennas, a new approach came out in this field. This letter introduces a near-field focused (NFF) array antenna working on 2.4 GHz that has been developed to test a new idea based on the fact that electromagnetic waves would deliver their energy in watery substances. A good tradeoff tried to be achieved in the NFF antenna's features such as small focused spot, about 100 × 100 mm ² , 45 cm depth of focus, and the size of 40 × 40 cm ² of antenna in order to perform tests of this new application.