A novel scheme for power-combined frequency tripler adopting 2N diodes is proposed in this work. Even mode coupled suspended substrate stripline is used to divide and recombine the input and output power. The circuits of the tripler are printed on both sides of the substrate, with N diodes on the front side and the other N diodes on the back side. The front diodes and back diodes are in anti-parallel connection, and DC biased separately to increase the bandwidth and power capacity. Three Q-band prototypes with two, four, and six diodes are fabricated and tested. The output compression powers at output frequency of 43.5 GHz for two/four/six-diode tripler are 9.2, 11, and 12 dBm, respectively. Power capacity is improved with the proposed tripler. Optimum DC bias is also discussed in this work, and it is found that it first increases with drive power, and then drops when large drive power applied because of the increased series resistance of the diode due to high junction temperature.

Design guidelines for fractional-N phase-locked loops with a high spectral purity of the output signal are presented. Various causes for phase noise and spurious tones (spurs) in integer-N and fractional-N phase-locked loops (PLLs) are briefly described. These mechanisms include device noise, quantization noise folding, and noise coupling from charge pump (CP) and reference input buffer to the voltage-controlled oscillator (VCO) and vice versa through substrate and bondwires. Remedies are derived to mitigate the problems by using proper PLL parameters and a careful chip layout. They include a large CP current, sufficiently large transistors in the reference input buffer, linearization of the phase detector, a high speed of the programmable frequency divider, and minimization of the cross-coupling between the VCO and the other building blocks. Examples are given based on experimental PLLs in SiGe BiCMOS technologies for space communication and wireless base stations.

Magnetic coupling resonance wireless power transfer technology has attracted worldwide attention in recent years due to its mid-range, non-radiative, and high-efficiency power transfer. However, in regard to its practical applications, there are still some issues that need to be considered and studied with respect to coil design, such as coil structure, and parasitic parameter extraction. This paper investigated the characteristics of magnetic coupling resonance wireless power transfer systems with different coil structures, including circular coils and rectangular coils arranged in parallel. We calculated the magnetic field distributions and mutual inductances by subdividing the receiving coils and computing the magnetic flux density of each subdivision. The proposed analysis was validated by means of the finite element analysis and the experimental results. We investigated the effects of the coil's structure, and topological structures, on the power transfer efficiency. The results demonstrate that using circular coils in parallel is more advantageous than using rectangular coils.

In this paper, a novel microstrip bandpass filter is proposed to enhance sideband selectivity, suppress harmonic frequency up to three-order as well as to keep a miniaturized size for frequency synthesizer application. The filter is constructed by four λ/4 folded stepped-impedance resonators (FSIRs) and two λ/2 stepped-impedance resonators at input/output ports to create three pairs of coupling paths and then to produce three cross-coupling transmission zeros (TZs) as well as to achieve a size miniaturization with 96% reduction compared with the conventional filter. By adding a common grounded metallized via hole among four λ/4 FSIRs of the filter, additional four mixed electric and magnetic coupling paths are set to generate extra four TZs. With these seven TZs, the proposed filter achieves a good sideband selectivity and harmonic suppression. Finally, the filter is designed, fabricated, and measured, its measured results are in well agreement with its simulated results.

This paper presents a novel ultra-low-loss high-pass filter with 3 dB cutoff frequency of 890 MHz for astronomical receiver radio frequency interference mitigation application. The filter consists of three series capacitors, four shunt inductors, and microstrip circuit board. Specially, 4 shunt inductors are actualized by fabricating air-core short-circuit coaxial cable inductors in the filter box body, and the quality factor of these cable inductors is up to 762.2 and 1046, respectively, at 1.4 GHz. In the expected passband of 1.1–1.9 GHz, S parameters measurement show that insertion loss is lower than 0.16 dB and two-port return loss is larger than 20 dB; noise measurement show that filter noise temperature is lower than 8 at 300 K ambient temperature. Noise sources of this filter are analyzed by simulation and measurement.

In this paper, a novel two-stage fish spear-shaped multimode resonator (MMR)-based ultra wideband (UWB) bandpass filter (BPF) is presented. The fish spear-shaped MMR is loaded with stepped impedance resonator in order to improve the out-of-band performance of the proposed filter. The proposed UWB BPF filter has fractional bandwidth better than 110%. In order to validate the present design approach, the filter is fabricated on RT/Duroid 5880 having dielectric constant 2.2, thickness 0.787 mm and loss tangent of 0.0009. The measured passband bandwidth of the filter is from 3.3 to 11.85 GHz, with insertion loss of 1.5 dB and return loss better than 12 dB in the passband. The proposed filter has sharp selectivity and upper stopband with 20 dB attenuation from 12 to 24 GHz.

A miniaturized substrate-integrated waveguide (SIW) power divider with embedded filter response and arbitrary power-dividing ratio loaded by open complementary split-ring resonators (OCSRRs) is presented. In the proposed power divider, the miniaturization and filtering response are realized by a pair of OCSRRs, which are etched on the metal cover of the SIW structure. The design procedure indicates that the power division ratio can be adjusted by changing the locations of the output ports. In this study, three miniaturized filtering SIW power dividers with different power division ratios (1:1, 1:4, and 1:8) are implemented to evaluate the performance of the proposed structure on the size reduction. These power dividers (1:1, 1:4, and 1:8) have the overall sizes of 0.31λg × 0.14λg, 0.25λg × 0.17λg, and 0.25λg × 0.18λg, respectively. The measured results also agree well with the simulated results.

A miniaturized Bagley Polygon power divider based on composite right/left-handed transmission line is presented. The composite right/left-handed transmission line and conventional microstrip transmission line are utilized to realize the 0° phase shift transmission line, which is used to replace the 180° transmission line of the conventional Bagley Polygon power divider. As a result, miniaturization is realized, without deteriorating the isolation between the output ports. The design equations are presented. This power divider shows advantages compared with other miniaturized ones. For verification, a miniaturized Bagley Polygon power divider is designed and fabricated. The 58.2% length reduction of the counterpart is realized. The measurement and simulation results show good agreement.

In through-the-wall radar imaging, multipath propagation can create ghost targets, which can adversely affect the image reconstruction process. However, unlike genuine targets, ghost positions are aspect-dependent, which means their position changes with the transceiver location. This paper proposes efficient ghost suppression methods exploiting aspect dependence feature under compressive sensing framework. This paper proposes a generalized signal model that accommodates for the reflections of the front-wall and target-to-target interactions, making the scheme more practical, yet the knowledge of the location of reflecting geometry is not a requirement as in most of the recent literatures. In addition, the sensing matrix is greatly reduced making the methods more attractive. Moreover, this paper investigates the influence of array configurations by examining two antenna array configurations: multimonostatic, and single-view bistatic configurations. Results based on synthesized data and real experiment show that the proposed method can greatly suppress multipath ghosts and hence increase signal-to-clutter ratio.

The well-known range-Doppler coupling property of the chirp radar makes it more vulnerable to different types of deceptive repeater jammers that benefit from the pulse compression processing gain of the radar-matched filter. These jammers generate many false targets that appear before and after the true target. Therefore, the radar cannot distinguish the true target from the false ones. This paper reviews different self-protection repeater jammers and presents their pros and cons, in order to provide a reference for the study of jamming/anti-jamming methods.

In urban target localization, the presence of walls creates virtual radars (VRs), which can be exploited to aid in localization process. The fact that multipath changes with the radar locations, which are referred to as aspect dependence property, enable us to find a radar location, which reduces wall uncertainties. This paper proposes single-antenna target localization in an enclosed structure taking advantage of VRs. Using ultra-wideband signals, we can resolve the target returns and estimate the correct location by solving monostatic loci at real and VR locations. Simulation results show that the method can precisely and accurately localize the target for a wide range of timing errors.

In this paper, a solid co-planar waveguide-fed fractal metamaterial antenna is offered. The proposed design consists of Sierpinski gasket iterations and a complementary triangular split ring resonator (CTSRR) loaded underneath the substrate, which is accountable for pull off multiband uniqueness and resolve good impedance identical. In sketch to hassle multiresonant frequency band facet, these CTSRR are entrenched reverse side of the substrate. The anticipated antenna with a dense dimension of 12 × 14 × 1.6 mm3 is fabricated and tested. The testing result designates that the projected design has −10 dB of 5.72, 14.3, and 16.06 GHz, respectively, and covers 5.72 GHz wireless local area network, 14.3 GHz fixed satellite, and 16.06 GHz International Telecommunication Union (ITU) band. It has fine emission uniqueness for jointly E-plane and H-plane in all the preferred occurrence bands and produce superior performance compared with the offered antenna intend in the prose. The loaded CTSRR construction recital is validated all the way during negative permeability pulling out and assorted parametric study.

A new single-feed aperture-coupled, X-band microstrip patch antenna array with circular polarization (CP) is designed. CP is achieved using indented microstrip patches fed through the slots on a substrate integrated waveguide. The antenna has the high radiation efficiency more than 90% over the operating frequency. Impedance bandwidth (VSWR < 2) and axial ratio bandwidth (AR < 3 dB) of 11.8, and 10.9% is attained, respectively. Good agreement is achieved between simulated and measured results.

The design and integration of penta-band planar antenna with a low noise amplifier (LNA) for vehicular wireless applications is discussed in this research. By integrating antenna with a LNA, the return loss can be kept low with the increased bandwidth compared with a passive antenna with the same design. The performance of the passive antenna, LNA, and integrated active antenna (IAA) are individually validated with the aid of vector network analyzer. The designed IAA covers navigational frequencies 1.2 and 1.5 GHz, wireless communication frequencies 2.4, 3.3 GHz and dedicated short range communication frequency 5.8 GHz, with LNA gain (>10 dB) and noise figure (<2 dB). The proposed design gives room for simultaneous reception of all the desired frequency bands with better performance for vehicular communications.

In this paper, a compact tri-band asymmetric coplanar strip (ACS)-fed meander-line antenna for wireless communications is proposed. Two inverted-L-shaped resonators are added to a simple meandered radiator for standard tri-band operation. Parametric studies indicate that operating frequencies of the proposed antenna are determined by the dimensions of the two inverted-L-shaped resonators. The measured results show that the proposed antenna can achieve three frequency bands; i.e. 1.48–1.63, 2.25–2.48, and 4.22–6.0 GHz. These bands can successfully cover the global positioning system L1, wireless local area network (WLAN), and HIPERLAN/2 operation bands, respectively. The proposed antenna exhibits good radiation patterns with reasonable gain and high radiation efficiency across the operating bands. In addition, the proposed antenna has compact size and simple feeding scheme, which make it suitable to be integrated within the portable device for wireless communications.