Volume 70, Issue 3-4 -

A hex-sided rounded dipole antenna (HSRDA) for UWB applications is presented. It is designed by the addition of semi-elliptical patch sections at the edges of a square bow-tie antenna. The antenna structure is fed by a modified microstrip feedline for better impedance matching. An impedance bandwidth of 2.9–11.4 GHz is achieved. The antenna structure has quasi omnidirectional radiation patterns and reasonable gain over the same frequency range. A good agreement between the experimental and simulation results is observed. The proposed antenna structure has miniaturized size for the same bandwidth as compared to already reported antenna structures.

In this paper, a Bow-tie antenna with size reduction, impedance matching and radiation pattern improvement characteristics is designed with an encircling ring. Moreover, further size reduction is achieved by utilizing two symmetric split rings with more frequency tuning flexibility. Research found the ring loaded Bow-tie antenna (RLBA) shows better performance than the referenced Bow-tie antenna (RBA), and the mechanisms of performance improvements are also investigated and found to be the loading ring acts as two symmetric dipoles in the direction of the antenna’s polarization. Then, using two symmetric split rings on the opposite side of the substrate as replacement of the encircling ring will prolong the length of the dipoles, and achieves further size reduction. The antenna is denoted as dual split ring loaded Bow-tie antenna (DSRBA). The low cutoff frequencies of RBA, RLBA and DSRBA with identical antenna size are 2.65 GHz, 2.27 GHz and 2.06 GHz, respectively. Then, the corresponding diameters of the antennas are 0.353 λ c , 0.303 λ c , and 0.275 λ c , where λ c are their corresponding wavelength of the lower cutoff frequencies. Furthermore, a notched-band is generated as a byproduct of the split rings, and it is owing to the new resonance of the overlap areas of the split rings. The notch can be used to alleviate interference of WiMAX band by carefully choosing the split rings’ size. Radiation patterns of RLBA and DSRBA are also improved as current distributions of the high frequencies are trained in order by the ring/split-rings. Measurements are performed to verify the designs.

This paper presents the design of two multi-band microstrip antennas. The antenna-1 gives Penta-Band and antenna-2 gives Hexa-band in the WLAN band. The frequency bands of the antenna-1 are Bluetooth 2.47 GHz (2.43 GHz–2.54 GHz), WiMax band 3.73 GHz (3.71 GHz–3.77 GHz), WLAN 5.1 GHz (4.99 GHz–5.13 GHz), upper WLAN 6.36 GHz (6.29 GHz–6.43 GHz), C band band 7.42 GHz (7.32 GHz–7.50 GHz) and the antenna-2 are WLAN band 2.6 GHz (2.56 GHz–2.63 GHz), 3.0 GHz (2.94 GHz–3.05 GHz), WiMax band 3.4 GHz (3.34 GHz–3.55 GHz), 4.85 GHz (4.81 GHz–4.92 GHz), WLAN 5.3 GHz (5.27 GHz–5.34 GHz) and upper WLAN 6.88 GHz. Both the antennas are fabricated and their measured results are presented to validate the simulated results. Proposed antennas have compact sizes and good radiation performances.

The article presents the design of triangular shaped fractal based antenna with circular slot for ultra wideband (UWB) application. The antenna is fed using microstrip line and has overall dimension of 24×24×1.6 mm 3 . The proposed antenna is covering the wide frequency bandwidth of 2.99–11.16 GHz and is achieved using simple fractal based triangular-circular geometries and asymmetrical ground plane. The antenna is designed and parametrical studies are performed using method of moment (MOM) based Full Wave Electromagnetic (EM) software Simulator Zeland IE3D. The prototype of proposed antenna is fabricated and tested to compare the simulated and measured results of various antenna parameters. The antenna has good impedance bandwidth, nearly constant gain and stable radiation pattern. Measured return loss shows fair agreement with simulated one. Also measured group delay variation obtained is less than 1.0 ns, which proves good time domain behavior of the proposed antenna.

This paper presents a planar notched antenna with a long meandered line for wireless USB dongle applications. The printed notched structure is used as additional resonators to generate multiple bands operation for covering GSM1800/1900/UMTS2100/LTE2300/2500 bands. In addition, with the help of the long meandered line via hole to ground, a lower resonant mode is sufficiently generated at around 770 MHz and forms a wider lower operating bandwidth (LTE700/GSM850/900). Briefly printed on a 0.8 mm thick FR4 dielectric substrate of size 20×70 mm² and electrically connected (via hole) to the ground plane of the USB dongle, the proposed antenna can provide a wide operating bandwidth (3:1 VSWR) of larger than 120 % centered at 2,000 MHz, allowing it to cover 698–960 and 1,710–2,690 MHz bands. The proposed antenna also can be attached to laptop computer by the USB interface. Detailed design considerations of the proposed antenna are described, and obtained experimental and simulation results are also presented and discussed in this paper.

In the paper, a singly fed circular patch antenna with polarization diversity is proposed, and its binary array for MIMO application is explored as well. The air substrate and aperture-coupled feed structure are adopted to increase bandwidth and simplify the bias circuit of PIN diodes. By controlling the states of four PIN diodes on the patch, the proposed antenna can produce linear polarization (LP), left- or right-hand circular polarization (LHCP or RHCP). For each polarization sense, the antenna exhibits wide impedance bandwidth, high gain and low cross-polarization. Two antennas are orthogonally placed to form a binary array for MIMO application, which has high isolation and low envelope correlation. The antenna and its array have advantages of simple biasing network, easy fabrication and adjustment, which can be widely applied in wireless communication systems.

Wireless transmission systems in smart metering networks share the advantage of lower installation costs due to the expandability of separate infrastructure but suffer from transmission problems. In this paper the issue of interference of wireless transmitted smart meter data with third party systems and data from other meters is investigated and an approach for solving the problem is presented. A multi-channel wireless m-bus receiver was developed to separate the desired data from unwanted interferers by spatial filtering. The according algorithms are presented and the influence of different antenna types on the spatial filtering is investigated. The performance of the spatial filtering is evaluated by extensive measurements in a realistic surrounding with several hundreds of active wireless m-bus transponders. These measurements correspond to the future environment for data-collectors as they took place in rural and urban areas with smart gas meters equipped with wireless m-bus transponders installed in almost all surrounding buildings.

The performance of a passive air surveillance sensor based on Global Navigation Satellite Systems (GNSS) is mainly limited by the receiver noise efficiency, the achievable signal processing gain and the radar cross section (RCS) of an airplane. For surveillance applications large detection ranges as well as a high probability of detection are crucial parameters. Due to the very low GNSS signal powers received on the earth’s surface, high radar cross sections are mandatory to achieve detection ranges for airplanes at some kilometers distance. This paper will discuss a multistatic transmitter and receiver arrangement, which is indispensable to get a reasonable detection rate with respect to a hemispheric field of view. The strong performance dependency of such a sensor on the number of transmitters and receivers will be shown by means of some exemplary simulation results.

The spectrum sharing system employing maximum ratio combining (MRC) is analyzed in Nakagami fading environment, for the case when the interference from the primary user is present at the input of the secondary user receiver. The closed-form expressions for the probability density function of the signal-to-interference-and-noise ratio, the outage probability and the ergodic capacity of the SU link are derived under both peak interference and maximal transmit power constraints. Asymptotical expressions are provided for the important region where peak interference power constraint dominates and the case when the interference from the primary user’s is dominant compared to the noise at the secondary user’s receiver. The obtained expressions are presented for both cases of outdated and mean-value based power allocation and verified by using Monte Carlo simulation method.

In this paper, the electromagnetic characteristics of the reported miniaturized bandpass filter (BPF) in reference are investigated deeply, and then a planar compact diplexer centred at 1.86/2.16 GHz is designed by using a T-junction to connect the reported BPFs. For verification, the designed diplexer are fabricated and measured. The measured and simulated results of the diplexer are in good agreement with each other, showing that the measured 3-dB bandwidth for the two passbands are 6.45 % (1.79–1.91 GHz) at 1.86 GHz and 6.94 % (2.08–2.23 GHz) at 2.16 GHz with return losses better than 20 dB. Moreover, the insertion losses of the two passbands are less than 0.7 and 0.9 dB, and the isolations are higher than 48 and 36 dB, respectively. Besides, compared with the diplexers reported in recent references, this one has more superior performances.

This study introduces a broadband microwave amplifier design that utilizes the measured scattering parameters of active devices without assuming an initial topology for the matching networks or an analytic form of the system transfer function. The algorithm can be extended to design multistage broadband microwave amplifiers. An example is given to illustrate the application of the proposed method. It was found that the proposed method provides very good initials for CAD tools to further improve amplifier performance by working on the element values.