Karlsruhe Institute of Technology (KIT) is doing research and development in the field of megawatt-class radio frequency (RF) sources (gyrotrons) for the Electron Cyclotron Resonance Heating (ECRH) systems of the International Thermonuclear Experimental Reactor (ITER) and the DEMOnstration Fusion Power Plant that will follow ITER. In the focus is the development and verification of the European co

Sentinel-1A is a space-borne synthetic aperture radar (SAR) system developed in the frame of the Copernicus Program. The German Aerospace Center supported the radiometric and polarimetric calibration of Sentinel-1A by the analysis of point target responses of several acquisitions considering different modes, beams, and polarization channels. An elevation dependent bias, which had not been properly

In this paper, a slow-wave transmission line implemented in coplanar waveguide technology, based on simultaneous inductive and capacitive loading, is presented for the first time. The shunt capacitors are achieved by periodically etching transverse strips in the back substrate side, connected to the central strip through metallic vias. The series inductors are implemented by etching rectangular sl

A selection of hybrid frequency- and time-domain approaches is evaluated with respect to their suitability for predicting the multi-tone behavior of a reference Ku-band helix traveling-wave tube. For this, a frequency-domain code is extended by a selection of frequency-dependent and frequency-independent envelope models and compared to a number of simulated and measured responses to two-tone signa

The present paper presents a novel method to cope with the difficulty that an -order filter can introduce a maximum number of transmission zeros (TZs) ? no more than . The method is described by a coupling topology and realized by a regular fully canonical filter structure to increase one more TZ for an -order filter without any filter size increase. Besides, the TZ shift property, as another adva

In this paper, a compact metamaterial inspired ultra-thin polarization independent quad-band microwave absorber for electromagnetic interference (EMI)/ electromagnetic compatibility (EMC) applications have been discussed. The proposed absorber structure offers four different absorption peaks having absorptivity of 97.02, 94.07, 91.72, and 98.20% at 3.40, 8.23, 9.89, and 11.80 GHz, respectively. Du

A novel idea for generating directional electromagnetic beam using a metamaterial absorber for enhancing radiation from a microwave antenna in the S-band is presented herewith. The metamaterial structure constitutes the well-known stacked dogbone doublet working in the absorption mode. The reflection property of the dogbone metamaterial absorber, for the non-propagating reactive near-field, is uti

An analytical method is proposed to reduce the memory effects and third-order intermodulation distortions for improving the linearity of wideband power amplifier (PA). An excellent linearity can be obtained by reducing the second-harmonic output power levels and reducing the envelope voltage components in the megahertz range. An improved wideband Chebyshev low-pass matching network including the b

A dual closed-loop stepped impedance resonator (DCLSIR) is investigated and used in designing a compact microstrip bandpass filter (BPF). The proposed DCLSIR is symmetrical; as a result, the symmetric characteristics of the resonator have been used. The design equations are derived and used to support the circuit design. The center frequency, position of transmission zeros, and fractional bandwidt

In this work, a simple and efficient approach to design a microstrip diplexer is proposed. It is based on the combination of two compact Square Open Loop Resonator band pass filters. These filters are designed for Radio Frequency Identification application at 2.45 GHz frequency. Using the Chebychev approximation, the two filters and diplexer are designed, simulated, fabricated, and measured. The r

In this paper, two new feed network designs for single layer and double layer slotted waveguide array antennas are presented. A microstrip to substrate integrated waveguide transition is applied to the single layer antenna. The aperture coupling mechanism is used in order to find the optimum feed network for double-layer structure and to obtain stable radiation characteristics over the frequency b

In this paper, an orthogonal crossover artificial bee colony (OCABC) algorithm based on orthogonal experimental design is presented and applied to infer the marine atmospheric duct using the refractivity from clutter technique, and the radar sea clutter power is simulated by the commonly used parabolic equation method. In order to test the accuracy of the OCABC algorithm, the measured data and the

In this paper, a single-feed dual-frequency dual-linearly-polarized dielectric resonator antenna is proposed which finds application in two- way internet satellite system and modern radar system. In order to achieve dual linear polarization at distinct frequencies, two rectangular dielectric resonators of same dimensions are excited in and modes by a narrow longitudinal and transverse slot, resp

A novel wideband circularly polarized printed antenna is proposed in this paper. It consists of asymmetrical ground and monofilar spiral stubs connecting to it. By employing an inverted L-shaped microstrip feedline to excite the slit etched in the ground and spiral stubs, a wideband culalry polarized performance of the proposed antenna is realized. After optimization, the measured results of the f

In this paper, a new miniaturized frequency agile filter-antenna with a wide reconfigurable frequency band is proposed for interweave cognitive radios (CRs). A tunable bandpass filter (BPF) composed of a symmetrical ring resonator is cascaded to the feed line of an ultra-wideband planar antenna. The structure of the proposed ring resonator BPF is simple and compact so that the total size of the pr

A quad band antenna with good gain and omni-directional pattern is proposed in this paper. The antenna design is based on loading a conventional monopole antenna by three different resonators. The resonators are inspired from the shunt branch of composite right-/left-handed cell. The resonators have a simple structure and compact size. The control of the frequency bands can be achieved arbitrarily

An integrated reconfigurable antenna capable of spectrum sensing along with various reconfiguration features such as polarization, frequency, bandwidth, and radiation pattern is proposed here. The proposed antenna senses the spectrum by UWB antenna from 2 to 11 GHz to identify the spectrum conditions. After identifying the direction of maximum traffic or interference, the proposed antenna accordin

This paper presents a novel asymmetric coplanar waveguide-fed quad-band hybrid antenna for wireless applications. The proposed hybrid antenna combines a conventional monopole antenna and a zeroth-order resonator antenna to perform a dual-mode operation. The first mode is generated by a slotted monopole antenna, supporting the two higher resonances at about 3.5 and 5.8 GHz. The second mode is suppo

In this paper, a high gain broadband low profile microstrip antenna with the dual-layered substrate and four parasitic metal elements is presented. The proposed microstrip antenna is mainly composed of four parts: four circular parasitic metal patches with dual arced breaches, a rectangular metal patch sandwiched between substrates, a square ground plane, and two-square substrates. The circular pa

This paper presents the design of all dielectric non-absorptive phase gradient reflective surfaces that can be used to manipulate the reflected electromagnetic waves at millimeter-wave regime. Compared with a bare perfect electrical conductor reflector which obeys the classical Snell's law of reflection, the presented design can effectively alter both the shape and level of the backscattered energ

We present a new ultra-wideband (UWB) band-pass filter (BPF) configuration with a stepped impedance short-circuited stub (SISS)-loaded triple-mode resonator (TMR) and stepped impedance radial stub (SIRS). The novel SISS-loaded TMR and SIRS improve the roll-off ratio at both ends. Even though this UWB BPF is based on a single resonator, the measured results show excellent in-band performance with a