A new approach for designing a single-feed circular microstrip antenna with dual-band/multi-band circularly polarized (CP) radiation are demonstrated and studied experimentally. It is presented that by embedding pairs of asymmetrical ring-shaped arc slots to the boundary of both circular patch and the ground plane the impedance bandwidth of the antenna increases. This can be achieved by making use of both mutual coupling between the resonances of the ring-shaped arc slots and the fundamental resonances of the circular antenna. Also, by extending the ring-shaped arc slots out with narrow slots, the circular microstrip patch antenna can perform dual-band/multi-band CP radiation. Further details of the proposed CP microstrip antenna designs are described, and typical experimental results are presented and discussed.

In this paper, a new configuration embedded with two filters and one resistor is proposed, which has the dual function of power splitting and filtering. The filter is based on stepped impedance ring resonator. All the even- and odd-mode resonant frequencies and transmission zeroes of the stepped impedance ring resonator are derived based on the even- and odd-mode analysis. Three interdigital-coupled lines are applied at the input port and output ports to achieve a bandpass response and suppress the second harmonic. For verification, a sample operating at the central frequency of 2 GHz is fabricated and tested. The measured results show the power divider has good performance on impedance matching, frequency selectivity, and isolation over the operating band.

This paper proposed a compact planar monopole antenna operating at 5 GHz (5.180–5.825 GHz) industrial, scientific and medical (ISM) radio band. The antenna constructed with 20 mm × 12 mm radiating element and 25 mm square of the ground plane in FR4 substrate provided −10 dB bandwidth of 1 GHz (5.4–6.4 GHz). To improve the bandwidth, parasitic elements are added with the monopole antenna. A capacitive feed is also incorporated in the design. It observed that the proposed antenna with parasitic elements provides a larger impedance bandwidth of about 3 GHz (5.1–8.1 GHz), which is three-fold improvements over the one without parasitic patches. The prototype of the antenna that operates at 5.8 GHz frequency range is fabricated and characterized using a near-field measurement system. A good agreement is found between the simulation and measured results.

In this paper, a simple and novel electromagnetic band gap (EBG) structure is proposed which offers a wide band gap and improved signal integrity. The unit cell of the structure consists of three square patches arranged in a particular fashion and connected by L-shaped bridges. Two of the square patches are shorted to the ground plane using vias. The unit-cell dimensions were taken to be less than half the operating wavelength at 2 and 2.5 GHz, at which the structure has been analyzed for signal integrity. A single unit cell of the proposed EBG structure is analyzed using IE3D, a method of moments based simulation tool. A single unit cell provides a band gap of 20 GHz starting from 10 MHz to 20 GHz. The prototype model for the unit cell is developed. A comparison between the simulation and measured results shows a good agreement. The improved signal integrity of the proposed structure is demonstrated both in terms of S-parameters and the eye diagram.

This paper presents a multiple-input and multiple-output dual-element planar inverted-F antenna (PIFA) array for broadband operation covering the HIgh PERformance radio Local Area Network/2 (5.2 GHz/5.6 GHz), Wireless Local Area Network (5.2 GHz/5.8 GHz), and the Worldwide Interoperability for Microwave Access (5.5 GHz) bands for the compact wireless communication devices. The antenna dimension is reduced substantially with a miniature ground plane. The PIFA array provides a large bandwidth (670 MHz) and a high isolation between its ports less than −26 dB. The proposed antenna has been analyzed and designed with Ansoft HFSS v.11. Then a prototype was fabricated and tested for its performance in terms of bandwidth, S-parameters, and radiation pattern. A parametric study is made to analyze the effect of different PIFA parameters on the operating frequency and the S-parameters. The diversity performances are evaluated using computer simulation technology microwave studio (CSTMWS). The broadband performance and the high isolation are achieved in both simulation and measurement.

Wireless domestic applications involving high data rates are required to work on millimeter wave band. Signal propagation at this frequency range is affected by walls and oxygen absorption which limits communication distances to few meters in one room. Radio coverage can be extended to other rooms by optical links. Performances of such photonic systems are dependent on optoelectronic devices, electrical driving, and receiver circuits. In this paper, radio-over-fiber (RoF) links based on the intensity modulation and direct detection technique are investigated for transmission of a broadband OFDM signal. Direct and external modulations are exploited to analyze system performances according to the ultra wideband (UWB) millimeter-band standard. To avoid component tolerances at high frequencies, an intermediate frequency modulation of the optical transducers is chosen. Optoelectronic and optical components of RoF links are modeled by equivalent electrical circuits with consideration of noise and nonlinearities. These models are validated in system simulation by error vector magnitude evaluation with a measurement setup according to the UWB centimeter-band standard.

It is difficult to detect a stationary object in practice, especially in an unknown indoor environment, because (a) there is no distinct speed difference between the targets and the background; (b) responses of the targets are contaminated by dense unknown clutter; (c) a priori knowledge of the background is not always available for some scenarios. In this paper, a set of ultra-wideband sensors are used to detect a stationary target with a planar diffuse surface. It is shown that, the relative spectrum-shifts of the data after data-projection operation, are closely connected to the illumination-angle differences. Based on this, a detector is designed, and the location and the orientation of the target are determined. In order to mitigate the influence of clutters, a “time-shift & accumulation” scheme is designed to enhance the signal. As a consequence, the signal-to-interference-and-noise ratio is increased. In addition, results from measurement in a realistic indoor environment are provided.

A finite-ground coplanar waveguide (FGCPW)-fed compact ultra-wideband flag-shaped monopole antenna is presented. The antenna consists of a FGCPW-fed monopole asymmetrically loaded with a rectangle strip. The antenna has a compact size of 21.85 × 28 × 1.6 mm3. Parametric analysis is conducted to understand the effect of various parameters on the antenna performance. Simple design equations are presented to provide reliable initial design of the antenna if a different substrate is to be used. Constant gain and monopole-like radiation patterns are observed along the entire operating range from 3.1 to 12 GHz. Investigation of the time domain characteristics reveals that the proposed antenna exhibits excellent pulse handling capabilities.

In this paper, we present a method for multiple target two-dimensional tracking using multiple sensors with very low azimuth resolution. Due to the scarce azimuth resolution, the data association is performed using range and Doppler information only from four radars. The proposed algorithm is tailored to perform in maritime scenarios. In order to test the algorithm performance, sea clutter data have been taken under consideration when simulating data.

This paper presents three iterations of a coplanar waveguide-fed H-tree fractal antenna. Increasing the number of iterations allows us obtaining a multi-band and broad-band behavior. The proposed antennas are a good solution for wireless local area networks IEEE802.11 a/h/j/n/ac/y, worldwide interoperability for microwave access system IEEE802.16, radio frequency identification, C-band, high performance radio LAN, and ultra wideband applications. The simulations were performed in FEKO 6.3. The measurements were performed by the network analyzer HP 8719C.

Wide band circular polarized (CP) antennas behind extended hemispherical lenses suitable for polarization sensitive THz detector and wireless communication have been designed and characterized using numerical simulation. Two novel, compact and CP dipole antennas are designed and studied for this purpose. CP property of planar antennas is achieved by geometrical modifications of antennas without any complicated feeding structure. Due to compact dimensions, wideband performance and CP behavior, these designs have applications in circular dichroism (CD) spectroscopy and terahertz detectors. This numerical study deals with polarization diversity with substrate lens, effect of off axis displacement on CP behavior of lens antenna which determines number of pixels for any application, far field patterns variation due to lens's internal reflection, directivity variation attributed to internal reflection and losses. Radiation efficiency variation of antenna by antenna dimensions is also studied carefully to design appropriate lens from application's point of view. Off axis performance of antenna on hemisphere lens is also studied and redesigning of antenna by some geometric modification has been carried out to improve far field patterns.

A new simple compact ultra-wideband (UWB) dielectric resonator antenna is presented. The antenna consists of a modified stepped microstrip-fed monopole printed antenna loaded with a rectangular dielectric resonator, truncated ground plane, and a parasitic strip underneath the dielectric resonator (DR). Using an optimized truncated ground plane and a combination of stepped feed line with DR an ultra-wide impedance bandwidth of 153% for (∣S11∣ ≤ −10 dB), covering the frequency range of (3.7–28 GHz) is achieved. The added parasitic strip can improve the radiation pattern, especially at high frequencies. The proposed antenna covers almost the entire UWB (3.1–10.6 GHz), Ku (12.4–18 GHz), and K (18–26.6 GHz) frequency bands. Also this antenna has an omnidirectional and stable radiation pattern over the whole operating frequency range and a compact size of (15 × 20 × 5.8 mm3) that make it suitable for wideband wireless system applications. This structure is light weight and can be easily fabricated. A prototype is built and measured. The simulated and measured results are in good agreement.

In this paper, we propose a novel integrated ultra-wideband (UWB) monopole antenna with dual-band antenna. The antenna consists of planar rectangular with semi-elliptical base and a rectangular dielectric resonator antenna (DRA) with dual-band operation. Both of them are excited via coplanar waveguide (CPW) lines. The experimental measurements show that the planar monopole provides an impedance bandwidth between 2.44 and 11.9 GHz which largely covers the entire UWB spectrum, and the rectangular DRA operates at two bands; 5.3–6.2 and 8.5–9.4 GHz. Additionally, the proposed structure ensures low mutual coupling between the two ports (with S21 less than −20 dB in the whole operating frequency band). The measured and numerical results show a good agreement.

The design and the results of a single slot coupled substrate integrated waveguide (SIW)-fed membrane antenna and a 1 × 4 array is presented for 94 GHz communication system. The membrane antenna is designed using Ansys high frequency structure simulator and consists of six layers. The microstrip patch antenna placed on the top pyralux substrate layer is excited by means of a longitudinal rectangular slot placed over the SIW structure in the bottom pyralux substrate. The simulated antenna impedance bandwidth is found to be 5 GHz (91.5–96.5 GHz) for both single element and 1 × 4 array. Furthermore, the gain is found to be 7 and 13 dBi for the single element and the 1 × 4 array elements, respectively. The results are verified using Computer Simulation Technology (CST) Microwave Studio and are found to be in good agreement.

In this paper a wideband multi-input multi-output (MIMO) antenna system for WiFi-LTE wireless access point (WAP) application is proposed. The MIMO antenna system consists of two common element microstrip-fed monopole antennas with dual polarization. Physically closed integration of MIMO antenna elements requires a special technique to increase the isolation between the antennas. A novel structure of parasitic element is introduced to improve the isolation between the antennas. The proposed MIMO antenna system is simulated and optimized using CST Microwave Studio. The designed antenna system is fabricated and measured to verify the simulation results. Reflection coefficient of less than −10 dB and isolation more than 15 dB are achieved in the operating frequency range of 2.3–2.9 GHz which covers WiFi 2.4 GHz and LTE 2.6 GHz bands. The proposed system also provides dual polarization with 10 dB polarization diversity gain and envelope correlation coefficient less than 0.15. Each individual antenna has a gain of 5.1 dB and 68% efficiency.

A reactive impedance surface (RIS) based miniaturized bent slotted patch antenna is proposed and investigated for S-band applications around 2.39 GHz. Bent slots in the patch reduce the patch antenna size by increasing current path on the patch. Further a RIS substrate with cross-shaped patch elements printed over a grounded dielectric is optimized and investigated for antenna miniaturization. The proposed bent slotted patch antenna over RIS substrate is 38.75% miniaturized with respect to traditional patch antenna at a fixed operating frequency. The proposed antenna reveals an overall volume of 0.280λ0 × 0.280λ0 × 0.036λ0 on a low-cost FR4 substrate at 2.39 GHz for S-band applications. The proposed antenna is fabricated and measured for its return loss. The measured results are in good agreement with simulated one.

A fast and efficient full-wave hybrid method for the analysis of a multilayered substrate integrated waveguide (SIW) based slot antenna/array radiating into a dielectric slab radome is presented. The antenna structure is modeled as a stacked parallel-plate waveguide hosting metallic posts and coupling and/or radiating slots. To account the radome effects on the SIW antenna, the physical optics method in conjunction with three-dimensional ray trace technique are used to analyze a dielectric slab radome staked on the aperture of the antenna. The field in the SIW structure is expressed by using an expansion in terms of vectorial cylindrical eigenfunctions. Enforcing the boundary conditions on posts yield the scattering amplitude, while slots are modeled as unknown magnetic currents which are found by solving the integral equation derived from the continuity of the field on the slot surface. A double-layered SIW cavity backed slot antenna radiating into a dielectric slab radome is analyzed, and the results compared with high frequency simulation software (HFSS) simulations. It will be shown that the proposed method is fast and efficient and gives results in very good agreement with the most common simulation tools.

This paper presents a tradeoff between isoflux pattern quality and X-band antenna compactness for nanosatellite applications. Having an isoflux radiation and a circular polarization (CP) generally causes a large antenna size which is incompatible for these applications. A new design of an antenna is done with the following maximum antenna dimensions: a diameter of 90 mm and a height of 20 mm above the nanosatellite platform. The isoflux pattern is slightly degraded while a good CP and realized gain are kept. The structure is a compact choke horn. It presents an axial ratio lower than 3 dB and a RG close to 0 dB over a 400 MHz bandwidth (8.0–8.4 GHz). It has been realized and successfully measured.