Abstract-A novel compact CPW (coplanar waveguide-fed) CPSS (Circularly polarized square slot) antenna is presented. The proposed single-layer antenna is composed of a rectangular ground plane embedded with two equal-size patches along two orthogonal directions. Equal amplitudes with 90 • phase difference values of two patches are capable of generating a resonant mode for exciting two orthogonal E vectors. Axial ratio (AR) bandwidth is significantly enhanced due to slot corner modification. The designed CPSS antenna is compact in nature with volume of 0.37λ 0 × 0.34λ 0 × 0.012λ 0 mm 3 (λ 0 = free space wavelength at centre frequency of the CP bandwidth). It has impedance bandwidth between 4.65-6.72 GHz (36.41%) and 3-dB axial-ratio bandwidth of 520 MHz (4.85-5.37 GHz), which covers 4.9 GHz (802.11j) WLAN for public safety ranging from 4.94 GHz to 4.99 GHz and WLAN (U-NII-1 and U-NII-2A) ranging from 5.150-5.350 GHz for indoor use. The gain variation for the frequencies within the CP bandwidth is also observed to be less than 0.4 dBic. The design is successfully implemented, and measured results are compared with the simulated ones, which are found good agreement.

In this paper a novel branch-line printed inverted-F antenna (IFA) loaded with a rectangular complementary split-ring resonator (CSRR) is proposed, designed, and experimentally studied. The proposed antenna shows four operating frequencies and can be used for various cellular and wireless applications (900 MHz/3.5 GHz/4.2 GHz/5.5 GHz). The antenna is compact in size having dimensions 0.059λ 0 × 0.053λ 0 × 0.002λ 0 at the lowest resonance frequency. Each of the bands is independently tunable and shows circular polarisation (CP) in the WLAN band with linear polarization (LP) in the other three bands. The axial ratio (AR) bandwidth is 1.82% in WLAN band. The simulated and fabricated results are reported in terms of S-parameters and radiation pattern. The prototype of the antenna has been fabricated and measured using VNA and simulation done in ANSYS HFSS.

This paper presents a CPW-fed dual-band dual-sense circularly polarized square slot antenna (CPSSA). The antenna consists of a rectangular radiator with two unequal rectangular strips, connected by a CPW feed line. An inverted L-shaped grounded stub is placed in the right side of the slotted ground plane with the orthogonal direction of the feed line to create CP modes. The proposed antenna obtained two CP bandwidths of 3.30-3.78 GHz and 5.4-5.86 GHz with axial ratio (AR) value less than 3 dB, and both the CP bands are overlapped by impedance bandwidth (IBW) of the antenna, ranging from 2.72 to 7.34 GHz. Total size of the proposed antenna is 50× 50× 1.58 mm 3. The antenna is fabricated on an FR4-epoxy substrate and measured. Simulation results are verified by measurement for the given antenna. The designed antenna is well used for WiMAX (3.5 GHz and 5.5 GHz) band with CP characteristics. Design procedures of the antenna are discussed in details for further understanding of the antenna design. Parametric study has been done for describing the mechanism of the dual-band CP with the analysis of electric current distribution of the antenna. Meanwhile, wide axial ratio bandwidth has been obtained in both the bands using this structure compared to other published structures.

In this paper, a simple approach for enhancing the gain of a planar dipole antenna using the concept of grounded metamaterial (MTM) has been proposed. In this regard, a magnetic metamaterial with Mu-very large (MVL) property has been placed over the ground plane of the antenna to increase the gain of the electric dipole source. A fully planar structure has been configured due to the placement of the metamaterial just over the ground plane. A significant amount of gain improvement of about 3.7 dB for the dipole has been attained using the metamaterial. In addition, increase of fractional bandwidth by 2.2% has been obtained due to the loading of the metamaterial. A comparative study with respect to recently reported literature for the gain enhancement of planar dipole has also been discussed. The proposed antenna is a worthy candidate for wireless communication owing to the high gain, low profile, and wide bandwidth characteristics.