In this paper a novel low pass filter (LPF) design procedure is proposed for electromagnetic bandgap based microstrip filters without using classical filter design approach. LPF is designed for ultra-wide stopband and sharp roll-off rate via proposed design procedure. It has been shown that finite periodic fan-shaped defected ground structures (FSDGSs) and double radial stubs (DRSs) yield broad stopband and very sharp transition band. The proposed LPF has −3 dB passband from dc to 1.49 GHz, and −20 dB broad stopband from 1.65 GHz up to 7.41 GHz. Full wave electromagnetic (EM) simulation of the proposed filter is achieved with ANSYS's High Frequency Structure Simulator (HFSS) and equivalent circuit (EC) model of the filter is proposed and verified via Applied Wave Research (AWR) software. To verify the simulations, filter is realized on ARLON AD1000 substrate, and measured with Agilent 5245A PNA-X Vector Network Analyzer. Measurement results of fabricated filter are in good agreement with EM and EC simulations.

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.

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.

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.

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.

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.

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.

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.