This paper presents a close but a beginner's perspective and a comprehensive review of microstrip filters with defected ground structure (DGS). The concept of DGS is inspired by photonic/electromagnetic bandgap structures (EBG/PBG) and metamaterials that are employed in microwave components to achieve a variety of performance enhancement features. Modeling of DGS and metamaterials as an L-C equivalent lumped circuit is much simpler in comparison with complex EBGs/PBGs. In this review, we have given a detailed account of the microstrip filters using DGS.

Radar sensors are key components of modern driver assistance systems. The application of such systems in urban environments for safety applications is the primary goal of the project “Radar on Chip for Cars” (RoCC). Major outcomes of this project will be presented and discussed in this contribution. These outcomes include the specification of radar sensors for future driver assistance systems, radar concepts, and integration technologies for silicon-germanium (SiGe) MMICs, as well as the development and evaluation of a system demonstrator. A radar architecture utilizing planar antennas and highly integrated components will be proposed and discussed with respect to system specifications. The developed system demonstrator will be evaluated in terms of key parameters such as field of view, distance, and angular separability. Finally, as an outlook a new mid range radar (MRR) will be introduced incorporating several concepts and technologies developed in this project.

This paper describes the establishment of a test setup for measurement of passive inter-modulation (PIM) products generated by various device(s) under test (DUT(s)) (filters, coaxial cables etc.) at ultra high frequency (UHF) band. The paper begins with a brief discussion of an ideal PIM test setup using a quiet load. It then discusses the establishment of the setup in the absence of quiet load and demonstrates a PIM level of −192 dBc of the test setup. Finally it shows the PIM performance of a band-stop filter, a flexible cable, cascade of band-stop filter, and flexible cable, measured using the established test setup. These components are required for UHF payload of a communication satellite.

In this paper, the design and the measurements of three-dimensional through silicon vias (TSVs) based-integrated solenoids embedded within high-resistive silicon is presented. Prior to silicon implementation, a rigorous theoretical analysis is proposed to put in obviousness the advantages of using such coil architecture for L and S band applications. This analysis, demonstrates a clear reduction of the footprint passive function lying on the external substrate together with a reduced capacitive coupling with the local environment. Two-port radio frequency measurements have been performed in a wide-frequency range (100 MHz – 50 GHz) in order to support the theoretical investigations. Solenoids exhibit high-quality factors below 4 GHz – Q = 25 @ 2 GHz for a 800 pH device – and clearly outperforms classical planar architecture considered in most of the integrated circuit processes. Two different modeling approaches (compact modeling and EM modeling) are then proposed in order to speed-up their design implementation in a typical CAD design flow. Based on the available data, a good agreement is shown between and simulated data.

This paper presents a detailed procedure to design substrate integrated waveguide (SIW) Tee-junctions with wide-range split-power ratio (from 1:1 to 1:8) and phase-balanced outputs. A set of curves was generated using an electromagnetic (EM) simulator to graphically determine the required parameters for the desired junction. Since such curves are provided, no further electromagnetic simulation is required when applying the proposed method. Input return loss at central frequency is guaranteed to be better than 18 dB. If an optimization procedure is required, the parameters obtained from this methodology may be used as initial values for such a process. Moreover, design rules are given for implementing 1 → 2N unequal power dividers with phase-balanced outputs. To demonstrate the accuracy of the proposed graphical method, three implementation examples are provided: two Tee-junctions and a 1 → 4 power divider.

In this paper, the benefits of adaptive preselect filtering are investigated by analyzing mote-to-mote throughput in the presence of interference. In a city-wide deployment of a sensor network, of the 150 wireless sensor nodes deployed in our urban test system, five nodes were electrically “lost”. Surprisingly, the limiting factor was not the signal strength, but the neighboring cell towers that caused nearby interference. Therefore, we explored the effect of an adaptive front end to mitigate these nearby interferers. The sensor motes operated at a fixed band, the unlicenced band of 902 to 928 MHz, and did not have the frequency adaptability of future cognitive radios. However, the effect was demonstrative of the potential benefits of adaptive preselect filtering. The measured result shows substantial improvements over the fixed band system by even slight tuning of the bandwidth and/or the center frequency of the preselect filter. Experimentally and numerically, we show that both tuning in the filter bandwidth and/or center frequency can significantly improve the packet reception rate. Guidelines for achieving an optimized filtering technique are given to provide a broad understanding of how the adaptable preselect filtering can be utilized.

This paper presents four continuously variable W-band phase shifters in terms of design, fabrication, and radiofrequency (RF) characterization. They are based on low-loss ridge waveguide resonators tuned by electrostatically actuated highly conductive rigid fingers with measured variable deflection between 0.3° and 8.25° (at a control voltage of 0–27.5 V). A transmission-type phase shifter based on a tunable highly coupled resonator has been manufactured and measured. It shows a maximum figure of merit (FOM) of 19.5°/dB and a transmission phase variation of 70° at 98.4 GHz. The FOM and the transmission phase shift are increased to 55°/dB and 134°, respectively, by the effective coupling of two tunable resonances at the same device with a single tuning element. The FOM can be further improved for a tunable reflective-type phase shifter, consisting of a transmission-type phase shifter in series with a passive resonator and a waveguide short. Such a reflective-type phase shifter has been built and tested. It shows a maximum FOM of 101°/dB at 107.4 GHz. Here, the maximum phase shift varied between 0° and 377° for fingers deflections between 0.3° and 8.25°.

Resonant substrate integrated near-field sensors are used for characterization of aqueous solutions at three different frequencies. In addition, Chinese hamster ovary (CHO) cells in a culture medium are characterized with the same sensors. Different concentrations as well as different vital states of cell suspensions are examined. The complex permittivity of the samples is evaluated using a linearized method based on perturbation theory. The permittivity differences between the measured cell suspensions are discussed. The resonant frequencies of the sensors are close to 3, 7, and 11 GHz, respectively.

Embedded wafer-level ball grid array (eWLB) is investigated as a low-cost plastic package for automotive radar applications in the 76–81 GHz range. Low transmission losses from chip to package and board are achieved by appropriate circuit and package design. Special measures are taken to effectively remove the heat from the package and to optimize the package process to achieve automotive quality targets. A 77 GHz radar chip set in eWLB package is developed, which can be applied on the system board using standard solder reflow assembly. These radar MMICs provide excellent radio frequency (RF) performance for the next generation automotive radar sensors. The potential for even higher system integration is shown by a radar transceiver with antennas integrated in the eWLB package. These results demonstrate that eWLB technology is an attractive candidate to realize low-cost radar systems and to enable radar safety affordable for everyone in the near future.

Most non-linear behavioral models of amplifiers are based on functions that are analytic at the origin and thus can be replaced by their Taylor series development around this point, e.g. polynomials of the input signal. Chebyshev Transforms can be used to compute the harmonic response of the model to a sine input signal. These responses are polynomials of the input signal amplitude. A second application of the Chebyshev transform to the first harmonic response or radio frequency (RF) characteristic will lend the carriers and intermodulation (IM) products for a two-carrier input signal, again polynomials. An important class of non-analytic non-linear behavior encountered in practice, such as hard limiters and detectors are either empirically treated or only approximated by an analytic function such as the hyperbolic tangent. This work proposes to generalize the polynomial non-linearity theory by adding non-analytic at the origin functions that, like polynomials, are invariant elements of the Chebyshev Transform. Devices modeled with these non-analytic at the origin functions exhibit intermodulation behavior significantly different from that of classical polynomial models, giving theoretical foundation to a number of important unexplained practical measurement observations.

An analytical model is presented to improve the performance of the equilateral triangular microstrip antenna (ETMA). An improved model is presented taking into account the insertion of an air gap between the substrate and the ground plane, and High Tc superconducting material (HTS) for the triangular patch. The full-wave spectral domain technique in conjunction with the complex resistive boundary condition is used to calculate the characteristics including resonant frequencies, bandwidths, and radiation efficiency. Numerical results for the air gap tuning effect on the operating frequency and bandwidth of the high Tc superconducting triangular microstrip antenna (HTSTMA) are presented. The effect of temperature on resonant frequency and bandwidth of the HTSTMA are also given. The computed data are found to be in good agreement with results obtained using other methods.

The design and characterization of a new broadband small patch antenna, based on an innovative magneto-dielectric material and suitable for wearable applications at 868 MHz, is presented. To reduce antenna dimensions, while preserving its radiation and matching performance, a barium-strontium hexaferrite Ba0.75Sr0.25Fe12O19 has been synthesized as the antenna substrate to achieve magnetic permeability double than vacuum in the band of interest. First material realization is characterized and dispersive permittivity and permeability behaviors are included in the design of a small patch antenna with a shorting-plate. A button-size realization is obtained and its suitability for wearable applications is numerically and experimentally demonstrated on body with and without the presence of conductive shielding. Very good agreement with measurements is demonstrated for both matching and radiation performance of the antenna.

This paper presents a new macro modeling methodology for solid-state power amplifiers (SSPAs) and packaged transistors used in communication systems. The model topology is based on the principle of harmonic superposition recently introduced by Agilent Technologies' X-parametersTM combined with dynamic Volterra theory. The resulting multi-harmonic bilateral model takes into account the coupling effects of both short- and long-term memory in SSPAs. In this work, the behavioral model was developed from time-domain load pull and used to simulate the amplifier's response to a 16-QAM signal with specific regards to ACPR and IM3.

A K-band microstrip delay line based on parasitic reduced left-handed transmission line (LHTL) with interdigital capacitors and shunt inductors is demonstrated with the aid of printed circuit board technology. The proposed delay line has ground slots under the interdigital capacitors to reduce the parasitic capacitance. The time delay of the proposed LHTLs is approximately 2.6 times larger than that of the conventional LHTLs. The input return loss of the proposed LHTL at 24 GHz is −16.9 dB and less than −10 dB from 20.5 to 26.1 GHz.

An antenna concept for direction of arrival estimation in azimuth and elevation is proposed for 77 GHz automotive radar sensors. This concept uses the amplitude information of the radar signal for the azimuth angle and the phase information for the elevation angle. The antenna consists of a combination of a series-fed-array structure with a cylindrical dielectric lens. This concept is implemented into a radar sensor based on SiGe MMICs for validation. A two- and a four-beam configuration are presented and discussed with respect to angular accuracy and ambiguities.

In this paper, a new way of obtaining a band rejection in a ultra wideband (UWB) filter using a uniplanar Electromagnetic bandgap (EBG) structure is reported. The EBG structure has a bandgap centered at 6.69 GHz which is almost 38% lower compared with the conventional uniplanar EBG of same dimensions. A one-dimensional EBG structure coupled with a microstrip line provides a narrow bandgap, which is used in obtaining a notch in the UWB filter. Single notch UWB filters with variations in the placement of EBG are fabricated producing a notch centered at 5.19 GHz (wireless local area network (WLAN)). A dual notch (5.16 and 8.24 GHz (satellite communication)) UWB filter is also fabricated with two different unit cell EBGs'. Switchable and tunable notch band UWB filters are proposed.

In this paper, a complete design procedure, together with robust system validation approaches, is presented for implementing a high-performance re-configurable digital predistortion (DPD) test platform for compensating for nonlinear distortion and memory effects induced by radio frequency (RF) power amplifiers (PAs) in the transmitters of modern wireless communication systems. This hardware and software co-operated test system not only enables effective validation for DPD algorithm development, but also provides a high-performance and reliable hardware-based linearization test platform. The experimental test was applied on a medium power Doherty amplifier, which was designed for 3 G/4 G wireless communication base stations. By applying our DPD algorithms on the proposed platform, more than 30 dB improvements in adjacent channel power ratio can be achieved for Universal Mobile Telecommunications System and long-term evolution signal excitations.

A proximity-fed complementary Sierpinski gasket fractal with equilateral triangular shape resonator in multilayer structure to achieve dual-band behavior for WiMAX and WLAN applications has been proposed. An electromagnetic coupled stacked structure of two different patches operating at two frequencies (3.5 GHz WiMAX and 5.8 GHz wireless LAN) has been designed for dual-band wireless applications. Proposed antenna was simulated using CST Microwave Studio based on the finite integration technique (FIT) with perfect boundary approximation (PBA). Finally, the proposed antenna was fabricated and some performance parameters were measured to validate against simulation results. The design procedures and employed tuning techniques to achieve the desired performance are presented.

This paper presents a hybrid antenna design for an optically powered super high frequency (SHF) radio frequency identification transponder applicable for the integration into metal. The key feature of the antenna is its ability to receive microwave signals at SHF for data communication and optical signals for the power supply of the transponder. The antenna design is based on a circular waveguide which is filled with a bundle of polymer optical fibers to guide light to the photodiodes. In addition, a transition is placed within the circular waveguide to transfer the waveguide mode of the SHF signal into a microstrip mode which is a more suitable structure for the integration of electronic transponder components. This paper discusses the constraints and solutions for the aforementioned combination of SHF microwave and light. The figures of merit of the optical power supply are presented, including considerations of the light distribution and the obtained power as a function of the incident angle and the used polymer optical fiber diameter. Furthermore, the measured gain and return loss of the SHF antenna structure is compared to the simulated results.

In this paper, radar transmitter circuits for next generation automotive radar sensors are presented. A 79 GHz radar transmitter with an output power of 14.5 dBm consuming only 165 mA (including frequency dividers) from a 3.3 V supply voltage clearly shows the advantage of using an improved SiGe technology with an fmax of 380 GHz. In addition, two radar transmitters for higher frequencies (around 150 GHz) based on frequency doubler circuits are showing the potential of SiGe technologies. The first transmitter achieves an output power of 3 dBm (single ended) at 144 GHz, whereas the second transmitters delivers a differential output power of 0 dBm at 150 GHz. Both transmitters achieve an ultra-wide tuning range of about 45 GHz.