A wideband widebeam dual-polarized magneto-electric (ME) dipole antenna is presented. The antenna element is implemented by orthogonally combining a pair of slotted stair-shaped radiators, stair-shaped feed lines, and metallic columns to impart a wide impedance bandwidth and beamwidth. Simulated and measured results show that the antenna has stable radiation performance with a return loss of better than 10dB in the span of 1.85-3.65GHz (>65 % ). Over the bandwidth antenna gain varies from 2.44-6.28dB with 3dB beamwidth in the range of 113°-153°.

A compact circularly polarized two-arm Archimedean spiral antenna backed by a shallow cavity is presented. Different miniaturization techniques were incorporated to reduce the overall dimensions of the conventional cavity-backed spiral antenna. Rigorous iterations on the spacing between the spiral and cavity back plate were carried out to achieve optimum performance. The overall dimension of this fabricated antenna is $0.326^{\star} \lambda_{\mathrm{L}}$ diameter and $0.0393^{\star}\lambda_{L}$ height. The fabricated prototype antenna exhibits a measured VSWR bandwidth (VSWR $\leq 2$ ) of 1.4 GHz to 9.7 GHz and measured Axial Ratio bandwidth $(\text{AR}\leq 3\text{dB})$ of 1.3 GHzto 7 GHz.

A multi-layer tilted beam planar microstrip array for FMCW-SAR application is presented. The proposed 8×4 array antenna exhibits a beam tilt of 30 degrees in E-plane with a sidelobe level of 18dB and 20dB in H-plane without tilt. The inherent radiation pattern degradation of the array due to feed radiation is minimized with the proposed multilayered concept. The proposed design exhibits an improvement in sidelobe level of the order of 6dB in both E-and H-planes with better cross-polarization level. In the multi-layered design, the common ground plane separating the two stacked substrate layers, shields the antenna half-space from spurious radiation emitted from the feed network. The simulation results show that the radiation pattern in the operating frequency provides a 3dB beamwidths of 25° and 9° in E-plane and H-plane respectively. Array exhibits a gain of 20dBi at the centre frequency and cross polarization level of better than 15dB.

A multi-layer planar microstrip array at X-band is presented for FMCW-Synthetic Aperture Radar application. A comparative study is provided for conventional corporate fed array and multilayered (proposed) array configurations. The proposed design exhibits an improvement in sidelobe level of the order of 6dB in both E-and H-planes with better cross-polarization level. The common ground plane separating the two stacked substrate layers, shields the antenna half-space from spurious radiation from the feed lines. The simulation results show that the radiation pattern in the operating frequency provides sidelobe level better than 23dB and 21dB with a 3dB beamwidths of 23° and 9° in E-plane and H-plane respectively. Array exhibits a gain of 21dBi at the centre frequency and cross-polarisation level of better than 30dB.

A novel technique for obtaining low sidelobes pattern in a planar microstrip array antenna is proposed. This technique involves the addition of two external complementary split ring resonators (CSRRs) at both the ends of each row of the antenna in the ground plane. These two CSRRs together produce an interferometer pattern for the reduction of sidelobes. An 8×4 planar array at 9.9 GHz is designed and fabricated to demonstrate the concept and a sidelobe reduction of 4.3 dB achieved.

A frequency reconfigurable wide slot antenna is presented. The proposed antenna is capable of switching the frequency bands between 1.3 and 2.7 GHz. The antenna has an overall dimension of 70mm × 70mm × 1.6mm, with a wide slot printed on one side of the substrate (RT Duroid5880, εr=2.2). A 50 Ω microstrip line printed on other side of the substrate is used to feed the slot. The antenna resonates at different frequency bands depending upon the feed line length. Hence the frequency re-configurability is achieved by varying the length of the feed line. When the length of the feed line is 30mm antenna resonates at 2.5GHz with an impedance bandwidth of 16% (2.25-2.65 GHz). For the feed line length of 40mm antenna resonates at 1.4GHz with an impedance bandwidth of 22% (1.31-1.62GHz). When the feed line length is changed to 60mm antenna resonates at 2.65GHz with an impedance bandwidth of 3% (2.61-2.69 GHz). The simulated and measured return loss and radiation pattern results for the proposed antenna are presented.

The effects of corporate feed network on the performance of low sidelobe level (SLL) planar array operating in X-band are analyzed. The impedance distribution at the individual sub-arrays is optimized to suppress the effects of corporate feed radiation and to achieve the required low sidelobe level (~20dB). Conventional planar feed design exhibited a distorted radiation pattern with second sidelobe level shooting upto -14dB. The proposed approach reduces the second sidelobe level and maintains nearly Gaussian tapered radiation pattern over the angle. Measured gain of the array is 21dB.

A compact printed planar antenna fed asymmetrically by a 50 Omega microstrip line is presented. This novel structural configuration is derived from conventional printed rectangular monopole, by introducing feed-line asymmetry to offer octave band end-fire radiation patterns. A rectangular ground plane of considerably small length and modified in shape with two symmetrical bevel slots on the upper edge, illustrate significant improvement in the input impedance matching of the antenna over the operating bandwidth. The influence of the length of the radiation patch and thickness of the dielectric substrate on the gain of the antenna is explored numerically. By linearly tapering the radiation patch, significant improvement in gain is observed. Both numerical and experimental reflection coefficient results confirm that the proposed antenna presents an impedance bandwidth of 94% for reflection coefficients less than -10 dB. The measured results present an optimum gain of 11.8 dBi and stable unidirectional radiation patterns. This novel antenna has wide impedance bandwidth, compact size and reasonably high gain, suitable for various broadband applications including point-to-point communication. The antenna is simple in structure with very few design parameters.

A novel coplanar waveguide (CPW) antenna is proposed for dual-band WLAN applications. It comprises a rectangular patch, a rectangular notch cut at the lower edge of the patch and a CPW transmission line. The rectangular patch together with the ground plane of the coplanar waveguide radiates at the lower frequency band, 2.4 GHz for IEEE802.11b/g, while the rectangular notch resonates in the upper band, 5.2/5.8 GHz for IEEE 802.11a. The designed antenna is only 32 x 5 mm, which can provide stable omnidirectional radiation patterns with an average gain of 2 dBi in both the bands. The antenna is very compact and suitable for 2.4 and 5.2/5.8 GHz WLAN operations.

A compact planar ultrawideband (UWB) antenna with band notched characteristics is presented. Modification in the shape of radiation element and ground plane with two symmetrical bevel slots on the lower edge of the radiation element and on the upper edge of the ground plane makes the antenna different from the rectangular printed monopole. These slots improve the input impedance bandwidth and the high frequency radiation characteristics. With this design, the reflection coefficient is lower than 10 dB in the 3.1-10.6 GHz frequency range and radiation pattern is similar to dipole antenna. With the inclusion of an additional small radiation patch, a frequency-notched antenna is also designed and good out of band performance from 5.0-6.0 GHz can be achieved. Measured results confirm that the antenna is suitable for UWB applications due to its compact size and high performance. Also an approximate empirical expression to calculate the lowest resonant frequency is proposed.

A new microstrip‐fed triple band antenna is presented for satisfying wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications simultaneously. The antenna comprises a rectangular monopole fed by a microstrip transmission line to generate WLAN and WiMAX frequency bands and a circular disc monopole to resonate in 3.5 GHz WiMAX frequency band. A simple formula for calculating the resonant frequency is given. The antenna is simple in configuration outlining an overall dimension of 44 × 20 × 0.76 mm3. The measured 10 dB bandwidth for return loss is from 2.37 to 2.7, 3.23 to 3.70, and 4.29 to 6.58 GHz for WiMAX and WLAN applications. © 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2481–2485, 2009; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.24650

A novel planar elliptical disc monopole antenna for universal mobile communication systems (UMTS) and ultra-wideband (UWB) dual network applications is presented. Printed on a FR4 dielectric substrate and excited by a microstrip transmission line, the antenna has a shaped ground plane featuring a wide impedance bandwidth with excellent omnidirectional pattern stability.

A novel microstrip-fed dual-band printed antenna for wireless local area network (WLAN) is presented. The antenna comprises a rectangular and a circular radiating element, which generate two resonant modes to cover 2.4/5.2/5.8 GHz WLAN bands. The design was experimentally verified by constructing the antenna on a FR4 (epsilon(r) = 4.4) dielectric substrate (47 mm x 26 mm x 0.76 mm) and measuring its impedance and radiation characteristics at both the bands. The measured 10 dB return loss (VSWR 2: 1) bandwidth in the 2.4G Hz band is 550 MHz (2.1-2.65 GHz) and it covers the bandwidth required for 2.4 GHz WLAN. The 5.2/5.8 GHz resonant mode has a bandwidth of 950 MHz (5.15-6.1 GHz) covering 5.2/5.8 GHz WLAN bands. A rigorous experimental evaluation confirmed that the dual-band printed antenna maintained good radiation characteristics with minimum cross-polarisation levels.

A new microstrip-fed triple hand antenna is presented for satisfying wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications simultaneously. The antenna comprises a rectangular monopole fed by a microstrip transmission line to generate WLAN and WiMAX frequency bands and a circular disc monopole to resonate in 3.5 GHz WiMAX frequency band. A simple formula for calculating the resonant frequency is given. The antenna is simple in configuration outlining an overall dimension of 44 x 20 x 0.76 mm(3). The measured 10 dB bandwidth for return loss is from 2.37 to 2.7, 3.23 to 3.70, and 4.29 to 6.58 GHz fro WiMAX and WLAN applications. (C) 2009 Wiley Periodicals, Inc. Microwave Opt Technol Lett 51: 2481-2485, 2009; Published online in Wiley InterScience (www.interscience.wiley.com) DOI 10.1002/mop.24650

A low pro. le printed antenna with triple band operation is presented for simultaneous use in wireless local area network (WLAN) and worldwide interoperability for microwave access (WiMAX) applications. The antenna consists of a rectangular radiating element fed asymmetrically by a 50 Omega microstrip line and a shaped trapezoidal ground plane. Rectangular horizontal strips are attached to the radiation element to form different current paths which make the antenna resonate in WLAN and WiMAX frequency bands. The antenna operates in dipole con. guration outlining overall dimensions of 38 x 30 x 0.8 mm(3).

A compact reduced size new Electromagnetic Bandgap (EBG) structure with multiple narrow slits unitcell in power plane is presented. By concatenating 2 × 2 high frequency unitcells a virtual low frequency EBG unitcell is created without changing the over all dimensions of the EBG making a compact design. Newly designed EBG operates over a frequency band of 0.9 GHz to 3.5 GHz with a good isolation of better than -40 dB over the band. The proposed design suppresses radiated emission (or electromagnetic interference) with in the stop-band. Emission characterisation has been carried out for both vertical and horizontally polarised signals and radiated emission of the new EBG is found to be small when compared with solid power/ground planes. Measured characteristics demonstrated a low emission from the EBG with an average value of 35dBuV/m. New EBG structure also exhibits low impedance which is less than one ohm over the stop-band for efficient prime power transfer.

A smooth‐wall pyramidal horn offering satisfactory performance over an octave bandwidth (in the frequency range 4–8 GHz) is reported. While the VSWR is 1.5 or better, the pattern and gain characteristics are also acceptable. The experimental results are presented and compared with those obtained by simulation. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 691–693, 2006; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.21444

This correspondence presents a top loaded dual sleeve antenna with a substantially small ground plane for broad band applications. The impedance and radiation properties of the monopole were investigated numerically and experimentally. The antenna features excellent radiation characteristics within a broad impedance bandwidth of 4.2:1, covering 0.5-2.1 GHz