A Ka-band carrier generator using phase-locked loop (PLL) frequency synthesizer is presented in this paper. The design uses integer-N PLL chip PE83336 as the important hardware support. The key idea of generating Ka-band frequency signal with low-phase noise is to generate a high-quality X-band frequency signal using PLL frequency synthesizer and employ a frequency multiplier to deliver the high-frequency output at the desired frequency band. Experimental measurements of the frequency synthesizer demonstrate the excellent performance, which is achieved with the Ka-band output with a frequency resolution of 5.7 MHz and phase noise better than −70 dBc/Hz at 1 kHz.

This paper presents a very flexible tool for numerically evaluating the small-signal and noise parameters of a transmission line subject to an arbitrary thermal gradient. Contrary to previous methods, the proposed approach allows straightforwardly taking into account possible variations of electrical parameters along the propagation direction, such as may be expected when temperature ranges between very different values. The main application of the proposed method is cable modeling in noise-figure measurement setups under cryogenic operation: in such circumstances, indeed, the coaxial cables (or waveguide) at the interface between the outside and the inside of the cryogenic chamber are subject to remarkable temperature excursions. As a consequence, significant de-embedding errors may arise if the cables are not correctly modeled, given the very low values of noise figure which are commonly exhibited by cryo-cooled active devices.

A tunable substrate-integrated waveguide phase shifter using low-temperature co-fired ceramic (LTCC)-technology is presented in this paper. By changing the effective permittivity in the liquid crystal (LC)-filled waveguide, the differential phase can be tuned continuously. This is achieved by means of an analog signal applied to the electrodes, surrounding the LC. The design allows for precise tuning of the differential phase, which is proven with a Monte Carlo measurement resulting in phase errors of less than 3° at 28 GHz. Besides that, the ambient temperature dependency of the module is shown. The phase shifter has a high integration level and can be included into a complete and lightweight single-phased array antenna module. The phase shifter is realized with a high level of integration which is available through the multilayer process of the LTCC. It has a length of 50 and provides a differential phase shift of more than 360° at 28 GHz. The figure of merit for tunable phase shifters is >40°/dB.

The design and fabrication of a wide-band programmable radio frequency (RF) feed network is proposed. It is designed to cover a wide band from 2.5 to 6 GHz over two separate branches. The feed network is simulated and fabricated on an FR-4 substrate with 0.8 mm thickness. Good matching between simulation and measurement results is achieved. The measured amplitude resolution was 0.5 dB with a maximum error of 0.22 dB. The measured phase resolution was approximately 5.6° with 1° maximum error. This design is a generic one that can be used in any kind of RF or antenna systems.

In this work, multi-mode resonator technology is applied to finline bandstop filter (BSF) to improve its performance. A finline BSF with two transmission zeros in the stopband is realized by using a new kind of dual-mode finline resonator proposed in this paper. The bandwidth of the designed filter is clearly broadened to three times that of the traditional finline BSF without enlarging its size. Its measured bandwidth under 20 dB rejection is about 600 MHz and the insertion loss in the passband is below 0.4 dB including the insertion loss of two finline-to-waveguide transitions. There is a good agreement between the simulated and measured results.

Novel design of low-pass microwave filters based on cascading of identical unit cells is proposed. Dispersion relation is used to determine the cell parameters for a given relative stop-band width. For a filter consisting of two cells, each made of single- or two-section transmission lines, the design formulas and curves are presented. Based on them typical filters are designed, fabricated, and measured. The presented filters feature a deep stop band and a wide rejection band, which can be controlled within the proposed design procedure. The design procedure and the simulation results are verified experimentally by measurement of the fabricated structures containing two and three cells.

An accurate characterization of microwave materials is essential for reliable high-frequency circuit design. This paper presents a measurement setup, which enables a quick and accurate determination of the relative permittivity of dielectric bulk materials up to 110 GHz. A ring-resonator is manufactured on a well-characterized substrate, serving as reference resonator. The material under test (MUT) is placed on top of the ring, which increases the effective permittivity and therefore introduces a shift of the resonance frequency of the resonator. In case of moderate to large dielectric losses of the MUTs, the quality factor of the resonator decreases perceptibly, which provides conclusions about the dielectric losses. Electromagnetic field simulations with different heights and relative permittivities of the MUTs provide a look-up table for the measured resonance frequencies. The functionality of the proposed measurement setup is validated by measurement results of different MUTs.

A novel coplanar waveguide-fed Z-monopole antennas are proposed for the first time for a industrial, scientific, and medical (ISM) band (2.4–2.48 GHz) applications. To make the designed antenna suitable for implantation, it is embedded in biocompatible Al2O3 ceramic substrate. The antenna operates at resonance frequency of 2.45 GHz to support wide band communication for high data rate implantable neural monitoring application. The size of the antenna is 38.675 mm3 (8.5 mm × 7 mm × 0.65 mm). The antenna was simulated and measured by immersing it in a phantom liquid, imitate the electrical properties of the human body phantom liquid. The simulated and measured bandwidths are 10.2 and 11.4% at the centre frequency. A study of the sensitivity of the antenna performance as a function of its dielectric parameters of the environment in which it is immersed was performed. The demonstration among the design EM characteristics of the antenna is presented by current distributions.

Prediction of millimeter(mm)-wave radio signals can be beneficial in recreating and repeating atmospheric conditions in a controlled, laboratory environment. A path-loss model has been proposed that accounts for free-space losses, oxygen absorption, reflection and diffraction losses, and rain-rate attenuation at mm-wave frequencies. Two variable passive low-pass-integrated circuit filter structures for attenuation in the 57–64 GHz unlicensed frequency band have been proposed, designed, simulated, prototyped in a 130-nm SiGe bipolar complementary metal-oxide semiconductor process, and measured. The filters are based on the Butterworth and Chebyshev low-pass filter topologies and investigate the possibility of using the structures to perform amplitude attenuation of mm-wave frequencies over a short distance. Both filters are designed and matched for direct coupling with equivalent circuit models of dipole antennas operating in this frequency band. Full integration therefore allows prediction of atmospheric losses on an analog, real-time, basis without the requirement of down-converting (sampling) to analyze high-frequency signals through a digital architecture. On-wafer probe measurements were performed to limit parasitic interference from bonding wires and enclosed packaging.

A simple and volume efficient circular antenna-array design with a low profile programmable beam rotation mechanism was presented. The proper selections of the rotation vector and the excitation coefficients of rectangular array-elements were made for rotation of the beam. The proposed rotation mechanism was capable to rotate the radiation pattern at any desired speed and to transmit in any desired direction, and the design included the ease of construction. Although simulating the radiation pattern using FEKO EM simulator, two basic functions, the power splitter and the introduction of phase difference, were included in feed network of microstrip circuit to divide the power and then individually feeding the each patch after introducing the desired phase difference.

A reconfigurable band-pass filter with switchable bandwidth, for wireless applications is demonstrated using a dual-mode microstrip square-loop resonator. The proposed filter has been designed on Rogers RO4003C and achieves switchable bandwidth by changing the length of two tuning stubs with the implementation of two strategically placed p-i-n diodes as switching elements. The filter was designed with a center frequency of 2.4 GHz and the two distinct operation states have bandwidths, 113 MHz (4.8%) with an insertion loss of 1.2 dB and 35 MHz (1.5%) with an insertion loss of 1.5 dB. The physical size of the fabricated reconfigurable filter including the implementation of the DC bias lines is comparable to the size of a conventional filter.

Nature inspired optimization algorithms, namely artificial bee colony (ABC) optimization and firefly algorithm (FA), have been applied to synthesize beam patterns of a hexagonal planar array of isotropic elements. Two different cases, comprising two different beam patterns of a pencil beam and a square footprint pattern over a bounded region with lower peak sidelobe levels are presented. The pencil beam is generated by thinning the uniformly excited array and the square footprint pattern is generated by imposing optimum amplitudes, phases, and their corresponding states (“on”/“off”) to the array elements. The optimum values of the parameters for both the cases are computed using ABC and FA individually, and the superiority of FA over ABC for the proposed problem in terms of computing solutions for both the cases is established.

In this paper, a rotated E-slot antenna with modified coplanar waveguide (CPW) feeding is presented to obtain broadband characteristics. The antenna comprises of a planar rectangular patch element embedded with E-slot rotated 90° anticlockwise on the radiating side. The CPW feed is modified by extending the ground plane throughout the substrate to surround the rectangular patch. This structure is capable of generating three separate resonant modes with good impedance matching. The antenna is designed on an FR4 substrate of 1.6 mm thickness, covering bands from 3.4 to 3.6 GHz for LTE and 3.4–3.694 GHz for worldwide interoperability for microwave access (WiMAX) systems. The proposed antenna provides good return loss S11 and impedance behavior.

In this paper, staircase-shaped ultra-wideband (UWB) response is proposed. UWB technology being emerging technology of decade needs development of antennas with small size. This paper proposed the design of antennas for UWB technology with small overall size. The feed used in the proposed design is microstrip feed line. The defected ground structure and staircase patch have been used to enhance bandwidth (BW) of antenna, to miniaturize its shape and to reduce the surface wave. The proposed design is carried out with different types of substrate materials and the best results are considered. The proposed antenna performs well in terms of BW and gain while reduction in size is reported. The proposed antenna can be used for Wireless Personal Area Network.

Different types of bondwire interconnect for differential chip-to-antenna and single-ended chip-to-chip interfaces are investigated. Two differential compensation structures for various lengths of interconnects are designed and experimentally evaluated using dedicated transmit and receive radar modules operating across a 110–156 GHz band. Measurement results demonstrate that a fractional bandwidth of 7.5% and a minimum insertion loss of 0.2 dB can be achieved for differential interconnects as long as 0.8 mm. Design and measurement results of an extremely wideband low-loss single-ended chip-to-chip bondwire interconnect that features 1.5 dB bandwidth from DC to 170 GHz and insertion loss of less than 1 dB at 140 GHz are presented as well. The results show that the well-established wire-bonding techniques are still an attractive solution even beyond 100 GHz. Reproducibility and scalability of the proposed solutions are assessed as well.

This paper presents the design of non-uniform concentric circular antenna arrays (CCAAs) of isotropic radiators with optimum sidelobe level (SLL) reduction. The biogeography-based optimization (BBO) method is used to determine an optimum set of excitation amplitudes that provide a radiation pattern with optimum SLL reduction with the constraint of a fixed major lobe beamwidth. The BBO method represents a new global evolutionary algorithm for optimization problems in electromagnetics. It is shown that the BBO results provide an SLL reduction that is comparable to that obtained using well-known algorithms, such as the particle swarm optimization (PSO), genetic algorithm (GA), and evolutionary programming (EP). Moreover, BBO results are compared with those obtained using the Matlab function Fmincon which uses a sequential quadratic programming (SQP) method. The comparison shows that the design of non-uniformly excited CCAAs using the SQP method provides a SLL reduction that is better than that obtained using global stochastic optimization methods, indicating that global optimization techniques might not really be needed in this problem.

In the present study, an ultra-wideband (UWB) antenna has been proposed using coplanar waveguide (CPW) feed with dual-band-notch characteristics. Slot-loaded radiator and U-shaped CPW resonator are used for band rejection at 3.5 and 5–6 GHz respectively to reduce interference with existing World interoperability for microwave access and wireless local area network systems. With an extended operating band (measured at 10 dB return loss) the antenna operates successfully over the entire UWB range (3.1–10.6 GHz) with a form factor of 30 × 20 × 1.524 mm3 on a commercially low-cost FR-4 substrate. Experimental measurement results are presented in support of the simulated results for the proposed antenna for practical application. The antenna has been successfully fabricated and measured, showing broadband matched impedance and good omnidirectional radiation pattern throughout the operating bandwidth. Measured time-domain analysis for both the orientations, i.e. face-to-face and side-by-side, yields excellent performance in the open environment scenario. With fairly good and consistent monopole such as omnidirectional radiation patterns in H-plane and linear transmission responses, the proposed antenna is well suited to be integrated within portable devices.

A 245 GHz sensor system for gas spectroscopy is presented, which includes a SiGe receiver (RX), a SiGe transmitter (TX), and a 0.6 m long gas absorption cell between the TX and RX. The integrated local oscillators of the RX and the TX are controlled by two external phase locked loops (PLLs), whose reference frequencies are swept with constant frequency offset for a low IF of the RX. The RX consists of a differential low noise amplifier (LNA), an integrated 122 GHz local oscillator (LO) with 1/64 divider, a 90° differential hybrid, and active subharmonic mixer. The TX consists of an integrated 122 GHz LO with 1/64 divider, and a frequency doubler. The RX and TX are fabricated in 0.13 µm SiGe BiCMOS with ft/fmax of 300/500 GHz. Using external dielectric lenses for the TX and RX, the absorption spectrum of gaseous methanol has been measured. The reference frequency of the TX-PLL is modulated for frequency-modulation spectroscopy. The performance of the sensor system is demonstrated by measuring the 2f absorption spectrum (second harmonic detection) of gaseous methanol.

This paper presents a designed notched band ultra-wideband (UWB) printed antenna using coplanar waveguide-fed configuration. Simple technique of perforating the substrate and modifying the ground plane and radiator patch was used to achieve UWB for the designed antenna at smaller structure. Narrow arch-shaped slot was introduced to the patch of the proposed antenna to obtain the band rejection function around the 5.4 GHz frequency to avoid the interference with WLAN applications. The proposed antenna was fabricated and the measurement result is found in well agreement with the simulation result. In addition to the acquirable UWB bandwidth, the designed antenna is capable to exhibit high radiation efficiency and omni-directional pattern.

This work presents a novel frequency miniaturized reconfigurable dual-mode stub-loaded resonator switchable from bandpass filter to single/double-notched bandnotch filter. The proposed filter topology employs RF PIN diodes as the switching device. Based on the odd- and even-mode equivalent circuits, the resonant characteristics of the proposed microstrip resonator are investigated. The defected ground structure pattern enhanced the performance; the 3-dB bandwidth reached 63%, with insertion loss of −0.5 dB. There was great sharpness of 55 dB in the low-frequency edge (from 1.7982 to 1.8466 GHz) and 33 dB in the high-frequency edge (from 3.4329 to 3.4995 GHz). The frequency-reconfigurable microstrip filter has been designed, fabricated, and measured for application in narrow band and ultra-wideband.