We review how a magnetic resonance force microscope (MRFM) can be applied to perform ferromagnetic resonance (FMR) spectroscopy of individual sub-micron size samples. We restrict our attention to a thorough study of the spin-wave eigen-modes excited in permalloy (Py) disks patterned out of the same 43.3 nm thin film. The disks have a diameter of either 1.0 or 0.5 µm and are quasi-saturated by a perpendicularly applied magnetic field. It is shown that quantitative spectroscopic information can be extracted from the MRFM measurements. In particular, the data are extensively compared with complementary approximate models of the dynamical susceptibility: i) a 2D analytical model, which assumes an homogeneous magnetization dynamics along the thickness and ii) a full 3D micromagnetic simulation, which assumes an homogeneous magnetization dynamics below a characteristic length scale c and which approximates the cylindrical sample volume by a discretized representation with regular cubic mesh of lateral size c = 3.9 nm. In our analysis, the distortions due to a breaking of the axial symmetry are taken into account, both models incorporating the possibility of a small misalignment between the applied field and the normal of the disks.

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Abstract-A novel compact microstrip resonator based on interdigital structure is proposed. The resonator has several times higher quality factor than similar resonators presented earlier. It is shown that the size of the resonator can be significantly reduced with substantial increase in quality factor by incrementing the number of pins in the interdigital structure. A 4-pole bandpass filter with central frequency 900 MHz and an overall size 4.6 mm 10.0 mm was designed and fabricated on the base of the proposed structure. The measured upper stopband of the filter was found to be up to at the level 40 dB.Index Terms-Bandpass filter (BPF), interdigital resonator, microstrip, microstrip resonator.

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A new quasi-lumped suspended-substrate stripline structure admitting implementation of miniature highly selective narrowband filters is studied. Appreciable improvement of the device selectivity is achieved with supplementary strip conductors introduced between the resonators, which induce attenuation poles near both passband edges. Furthermore, these supplementary conductors reducing the coupling between the resonators allow diminishing the interresonator spacing and the total size. A four-resonator filter is synthesized using the intelligence optimization method. Experimental results of the manufactured filter are presented.

Frequency-dependent coefficients of coupling between irregular microstrip resonators andtheir role in formation of filter frequency response are studied on the basis of energetic approach. Tworesonator segments and filters are used as samples under investigation. Theoretical analysis carried out in quasi-static approximation shows good agreement between calculated and experimental frequency responses and, thus, allows to conclude tlhat attenuation poles in frequency response are due to compensation of capacitive and inductive interaction between resonator. The data obtained shows a possibility to control the steepness of filter skirt slopes of by appropriate choice of structure parameters. .IntroductionIt is common knowleage that, frequency-selective devices, in particular, filters play critical roles in commuhication and radiolocation systems. Quite often these devices set the overall dimensions of radio engineering equipment, and also influence the quality and the failsafety of their work. It is also known, that in the microwave engineering are widely spread filters due to their compactness, failsafety and ability to be easy manufactured. Good agreement obtained between the quasi-static analysis of microstrip structures and experiments allows to create effective systems for the automated designing MW devices. Now important and actual are the tasks not only on creation of new filter designs, but also on optimization of known ones, in order to achieveextremely high performances in them.The resonators coupling coefficients study not only promotes the solving of such tasks, but also allows to understand regularities in behavior of frequency response (FR) of microstrip structures on changing their design data. In particular, research on frequency-dependent coefficients of coupling between microstrip resonators (MSR) with stepped change in width of a strip conductor, having dumbball shape, are of great interest [l]. Such resonators attract attention of specialists in the area of MW fi-equency-selective devices due to their compactness and higher, in comparison with regular resonators, unloaded quality factor, and also to opportunity of creating designs with the given spectrum of resonant frequencies [2]. Besides, the possibility of effective steepness control of FR slopes in band-pass filters based on irregular resonators allows to realize a given shape of FR with the minimal number of resonators in a device [3]. Thus, the construction of a filter not only becomes more compact, but also, as a rule, has the higher electrical performance in comparison with a filter based on regular MSR's with the same number of resonators. 2.Model and Method of CalculationThe researches was carried out on microstrip segments, consisted of two identical resonators located parallel against each other with the gap S between outside "low-impedance" parts of conductors, having width we (Fig. 1). Width of the middle "high-impedance" part is Wi and its length is la, while a total length of strip conductors of resonator is designated as I , . ...

A novel miniature stripline resonator performed on a double‐layer suspended substrate and bandpass filters (BPFs) based on it are proposed. The filters have wide stopband with high attenuation. A fifth‐order BPF has been designed and fabricated. The filter stopband at level of −100 dB extends up to the frequency that exceeds the passband center frequency by factor of 10. It is shown that miniature filters based on the proposed resonator could be effectively fabricated by low temperature cofired ceramics technology. © 2013 Wiley Periodicals, Inc. Microwave Opt Technol Lett 55:2866–2869, 2013

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