This paper presents a study of losses in substrate-integrated waveguides (SIWs) and cavities. Three mechanisms of losses are considered and separately investigated, namely radiation leakage, ohmic loss, and dielectric loss. A systematic comparison of waveguides with different geometry, operating at different frequencies, is reported. This study permits to give a physical interpretation of the loss mechanisms and to identify design criteria to minimize losses. A similar analysis is also developed in this work for the case of SIW resonant cavities. For these structures, a different variation of losses with respect to frequency is found, which reduces the effectiveness of the design criteria established for SIWs.

This paper discusses on the miniaturization of radiofrequency (RF) front-end components such as half-wavelength resonators based on new magneto-dielectric heterostructures combining high permeability (µ = 150–250) and high permittivity (ε = 18–150). Size reduction is evaluated by means of 2-cm-long coplanar waveguides realized with silicon technology and having a resonance frequency of about 3 GHz. The experimental results show a physical length reduction of 11.2% due to the dielectric contribution (ε = 18) and 14.8% by cumulating dielectric and magnetic effects (ε = 18 and µ = 150). These results are significant with respect to the moderate thickness of the preliminary material used here (only 150 nm). In a second part, a predictive model is proposed with µ and ε as variables. When adjusting the material properties in a realistic way (µ = 250 and ε = 150), the model predicts size reduction of ~50% for the same thickness. Larger values can be expected with increasing the film thickness.

Traditional millimeter-wave surface movement radar (SMR) has been designed and tested. A novel concept for the design of a new SMR is suggested based on synthetic aperture antenna and noise radar technology. It enables designing SMR without mechanical rotation of an antenna, but applying several nonmoving synthetic aperture antennas instead. Application of noise radar technology is also considered in more detail to improve the expected performance of a new SMR.

This contribution gives an overview of background, design, working principles, and management issues of some scientific highlights, and of the benefits of the Network of Excellence TARGET (Top Amplifier Research Groups in a European Team).

A new class of compact rectangular waveguide filters is proposed in this paper. The key element is a square ridge resonator realized within a rectangular waveguide supporting the fundamental TE10 mode. The square ridge can support two modes resonating along orthogonal directions in the gap between the ridge and the opposite waveguide wall. This structure enables dual-mode degeneracy without the need of oversized cavities, thus allowing for considerable size reduction with respect to the conventional dual-mode implementations. Different filter structures employing one or more ridges within short waveguide sections are proposed as attractive solutions for pseudo-elliptic band-pass or dual-band filters. The experimental results of a manufactured fourth-order pseudo-elliptic pass-band filter validate the feasibility of the proposed class of filters.

This article describes the design and performance of a compact tunable impedance transformer. The structure is based on a transmission line loaded by varactor diodes. Using only two pairs of diodes, the circuit is very small with a total length of only λ/10. Both the frequency range and the load impedance can be tuned by varying the varactor bias voltages. Our design provides a tunable operating frequency range of ±40% and an impedance match ranging from 20 to 90 Ω at 0.8 GHz and from 30 to 170 Ω at 1.5 GHz. In addition, a new approach that considers losses for the simulation and measurement of this impedance transformer was investigated. The measured performance of a 1 GHz prototype design confirmed the validity of this new approach.

Traveling wave amplifiers (TWAs) offer the advantage of broadband amplification and a closed set of equations that allow deriving the RF gain by means of treating TWAs as discrete transmission line approximations. Up to now, however, the significant losses associated with CMOS integrated inductors have been neglected. This work presents a new approach for determining the transmission line losses and phase constants that will bring about an enhanced gain prediction accuracy. The theory is verified by means of a realized design example. The working principle of the integrated DC supply inductor is discussed, whose performance is based on the inductors self-resonance effect. When applying a supply voltage Vdd of 2.4 V, the measured compression point P1 dB and the power added efficiency PAE at 2.4 GHz amount to 16.9 dBm and 19.6%, respectively. At 5.5 GHz, a value of 16.6 dBm for P1 dB and an associated PAE of 13.9% are achieved. The peak RF gain for these output power values reaches 11 dB, and values greater than 8 dB are obtained up to 7 GHz.

Piezoelectric materials have a strong interaction between their mechanical and electrical properties that translates into innovative components and circuits architectures. This work describes an original method using the electromechanical properties of the aluminum nitride (AlN) piezoelectric material to characterize its vertical extension when an electric field is applied. The novel techniques based on measurements of a planar parallel plate AlN capacitor without and with bias employing an impedance analyzer. The parallel plate capacitor theory and piezoelectric material analysis are used to calculate the vertical displacement of the AlN film.

A new model of two-access reconfigurable antennas for future mobile communication systems is presented in this article. This structure is based on a slot antenna with two separated access ports, isolated and matched at 1 and 2 GHz, respectively. The novelty of this element lies in the fact that first a filtering structure is integrated in the antenna, and then any additional switching or frequency path selecting components that would induce losses and noise degradation is suppressed. Such flexible structures are assumed to be used in a future opportunistic radio, incorporating special features of “spectrum sensing”. The concept of the antenna illustrated by simulation and measurement is presented.

This paper presents a feasibility study for the implementation of a concurrent dual-band power amplifier (PA) design suitable for 1.98 GHz WCDMA and 3.42 GHz WiMAX digital systems. The proposed PA design was compared with a test bed based on a pair of dedicated single-frequency band PAs. The dual-band PA exhibited simultaneous peak output power levels of 24 and 17 dBm in the lower and in the higher bands to maintain ACPR and EVM requirements below 33 dBc and 5%, respectively. The conclusions drawn in the paper justify the design effort of this innovative solution, which is capable of increasing the PAE for concurrent dual-band operation maintaining the performance of more conventional solutions.

In this contribution, fundamental design considerations for a novel metallization technique to realize millimeter-wave microstrip structures are presented. This hot embossing technology is a fast and economic process originating from the production of three-dimensional molded interconnect devices. Conductive structures are coated onto plastic parts or plastic foils using a heated stamp. This approach shows high potential and therefore will be investigated for the fabrication of low-cost printed antennas at millimeter-wave frequencies. The focus of this contribution is on design guidelines considering process parameters and interactions with substrate and copper foil characteristics derived from the fabrication and measurement of single microstrip patch antenna prototypes for radar applications in the industrial, scientific and medical (ISM) band at 24 GHz. Far-reaching potential lies in the utilization of the three-dimensional manufacturing technology for the construction of conformal integrated antenna systems based on the thermoforming capabilities of polymer substrates.

The capabilities of millimeter wave radars have been demonstrated for a long period of time for missile seeker applications and for automotive radars. The technological advantages of this type of radar can be adapted to security applications in air traffic management at short and medium range as well as on the ground. The application discussed in this paper focuses on inverse synthetic aperture radar (ISAR) imaging techniques for the derivation of high-resolution signatures of helicopters in the air and the determination of reference images using turntable measurements.

In this paper, the main nonidealities appearing in polar transmitters will be addressed, together with several implementation considerations. Special attention will be paid to the role of AM modulation nonlinearity and parasitic AM-to-PM conversion, once architecture mechanisms such as time-delay mismatch between branches or limited bandwidth in the amplitude path are controlled. The device limiting factors for a highly efficient switched mode operation and a linear amplitude modulation will be identified. Some circuit design and implementation guidelines for the RF modulating stage and the envelope amplifier will be discussed, to finish with system-level analysis considerations under two-tone and real communication signal excitations.

Detection in most surveillance radars is based on the condition of point targets against a more or less homogeneous background. Currently, the resolution of many new types of radar is increasing, at least in the range dimension. Therefore many objects can no longer be considered as points. Also as a consequence, the background is becoming more diverse, in statistical terms. The scene addressed in this paper concerns a ground clutter environment, and extended objects observed with a polarimetric radar with modestly high resolution (i.e. 6 m in range). A step-by-step approach is proposed for the detection and parameter assessment of extended objects and adding classification based on polarimetric features. The evaluation of this approach is based on recordings of real natural scenes and artificially inserted extended objects. It has been observed that in multi-stage detection object classification benefits from several features, including polarimetric ones. It is proposed that the quality of the contour circumscribing the object is the prime factor for quality of features next to polarimetric features. Clutter is affecting, however, the edges of the contours, and therefore may have a major impact on features that are dependent on the shape of these contours. The results also suggest that in the case of large targets with a basically simple shape, like ships, the eccentricity of the shape of the extended object is consistent from scan to scan and probably could support the target tracking.