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We report a synthesis process to design the defected ground structure (DGS)-based Bessel lowpass filter (LPF). For 5-pole LPF at f_c = 2.5 GHz, its selectivity is 10.6 dB/GHz and for the DGS-based Butterworth LPF it is 12.6 dB/GHz. For the lumped elements Bessel LPF, it is only 4.84 dB/GHz. Its 20 dB rejection bandwidth is 13.1 GHz and impedance matching BW is 76%, as against 88.8% for Butterworth LPF. At f_c = 7.5 GHz, the 5-pole DGS Bessel LPF has selectivity 7 dB/GHz, 20 dB rejection BW is 13 GHz and 10 dB return loss (RL) BW in passband is 4.86 GHz (64.8%) with less than 7.9 pS group delay (GD) variation. In case of a bulky mixed microstrip-waveguide (MMW) 5-pole Bessel LPF at 7.5 GHz [W. Menzel and F. Boigelsack, 29th European Microwave Conference, Munich (1999), pp. 191–194.], reported results are: sharpness of cut-off 1.48 dB/GHz, 10 dB RL BW and GD variation are 48% and 4 pS, respectively. The improved performance the DGS-based Bessel LPF can find applications in high speed data communication, front-end of a wideband communication system and in a power amplifier, by improving the selectivity, suppression of harmonics and linear distortion.

Microstrip Wilkinson power dividers with harmonic suppression and size reduction are investigated. It is found that by loading reactive components at the middle of high impedance transmission lines (TLs), both size reduction and harmonic suppression can be achieved. Analyses and designs of such a kind of power divider are formulated in this paper. To demonstrate the design methodology, two power dividers centered at 1.8 GHz are optimally designed and confirmed by experiments. As compared with conventional Wilkinson power divider, the proposed power divider exhibits 55.6% size reduction, and high suppressions are achieved for 2nd and 3rd harmonic components. Both simulations and measurements are presented with good agreement.

Design, fabrication and measurement of a high-selectivity dual-mode dual-band bandpass filter are presented in this paper. The resonance frequencies of the filter are 1.8GHz and 2.4GHz which are generated by a meander-loop resonator and a square-loop resonator. The two dual-mode single-band-loop resonators are stacked on each other and create a dual-band bandpass filter. Some advantages of our design are compact size, high selectivity, low loss and also no dependence of two bands, resonance frequencies on each other. The measurement results exhibit that the minimum insertion losses are 0.19dB for 1.8GHz and 0.32dB for 2.4GHz. Moreover return losses are better than 43.2dB and 40.6dB for 1.8GHz and 2.4GHz, respectively. The proposed filter has a size of $18\times 18$mm². This microstrip filter is fabricated on RT/Duroid6010 substrate with dielectric constant 10.8 and thickness 1.27mm and its equivalent circuit is also offered. The measured results exhibit good agreement with the simulated ones.

This paper presents a 6-gon-shaped bandpass and notch filters for Cognitive Radio (CR) applications. The bandpass filter consists of a 6-gon-shaped multiple mode resonator with interdigital coupling at both ends. The notch filter is derived from bandpass filter by embedding four identical Embedded Open Stubs (EOS) nearby the multiple mode resonators that introduce narrow band suppression in the desired passband. Such bandpass filter with notching band is required in practical CR systems in order to effectively sense the spectrum and avoid the interference between the systems working in same environment with the same frequency. The filter is simulated using an electromagnetic solver, IE3D. The group delay obtained for bandpass filter is below 0.2ns. With the above structural features, the overall dimension of the filter is $39.3\times 3.2$mm² and the fractional bandwidth (FBW) of the proposed bandpass filter is more than 100% with optimal performances in terms of insertion loss, return loss, group delay and phase.

This paper presents the design of Single and Double Layer microstrip patch antennas for ultra-wideband applications. This structure consists of a square patch with a partial ground plane, fed by a 50$\mathrm{\Omega }$ microstrip line. This antenna is designed for a system to detect malignant tumors by microwave imaging. Prototypes of the two antennas are fabricated and tested with a network analyzer. The proposed antenna can achieve an ultra-wide bandwidth with VSWR$<$2 from 3.82GHz to 11.72GHz for single layer antenna and from 3.2GHz to 10.95GHz for double layer antenna, with stable and bi-directional radiation pattern. The gain is good and has a peak value of 6.5dBi. The simulation of this antenna has been performed using Ansoft High Frequency Structure Simulator (HFSS) and Computer Simulation Technology-Microwave Studio (CST).

In this paper, a compact reconfigurable tri-band/quad-band monopole antenna is presented. To achieve the multi-band behavior, two right-angled triangles were etched in a conventional rectangular patch, and a partial ground plane is used. Moreover, the proposed multi-band antenna is printed on a low cost FR4 epoxy with compact dimensions of 0.23${\lambda }_0\times 0.23{\lambda }_0\times 0.012{\lambda }_0$, where ${\lambda }_0$ is calculated at the lowest resonance frequency. To provide frequency agility, a metal strip which acts as PIN diode was embedded in the frame of the modified patch. The tri-band/quad-band antenna performance in terms of reflection coefficient, radiation patterns, peak gain and efficiency was studied. The measured results are consistent with the simulated results for both cases. The simple structure and the compact size of the proposed antenna could make it a good candidate for multi-band wireless applications.

In this work, we have used a novel adaptive neuro-fuzzy inference system (ANFIS) method to design and fabricate a high-performance microstrip diplexer. For developing the proposed ANFIS model, the hybrid learning method consisting of least square estimation and back-propagation (BP) techniques is utilized. To achieve a compact diplexer, a designing process written in MATLAB 7.4 software is introduced based on the proposed ANFIS model. The basic microstrip resonator used in this study is mathematically analyzed. The designed microstrip diplexer operates at 2.2GHz and 5.1GHz for wideband wireless applications. Compared to the previous works, it has the minimum insertion losses and the smallest area of 0.007 ${\lambda }_g^2$ (72.2mm²). It has flat channels with very low group delays (GDs) and wide fractional bandwidths (FBWs). The GDs at its lower and upper channels are only 0.48ns and 0.76ns, respectively. Another advantage of this work is its suppressed harmonics up to 12.9GHz (5th harmonic). To design the proposed diplexer, an LC model of the presented resonator is introduced and analyzed. To verify the simulation results and the presented ANFIS method, we fabricated and measured the proposed diplexer. The results show that both simulations and measurements data are in good agreement, which give reliability to the proposed ANFIS method.

A miniaturized microstrip dual-band bandpass filter (DBPF) with two T-shaped resonators is proposed. The two T-shaped resonators lead to multiple transmission zeros in the stopband and higher filter selectivity. The filter is analyzed using LC and even/odd mode analyses to determine the transmission zeros. The LC equivalent circuit and transfer function are presented. The proposed filter is symmetrical, so the electrical length and impedance values are used for odd/even mode analysis. The designed DBPF is centered at 1.9/5.54GHz and is suitable for WLAN applications. The insertion loss of the filter is less than 0.5dB and its return loss is more than $-20$dB in each band. Five transmission zeros are created with an attenuation greater than $-20$dB. The total area of the proposed filter is $8.54\times 23.36$mm². To validate the proper performance of the proposed filter, it is fabricated and measured.

The CMS Silicon Strip Tracker (SST) integration has been completed. After an extensive period of testing with cosmic muons the detector is ready for the final installation inside the CMS magnet. This paper will review the integration procedures and the tests completed to ensure that SST performs according to specifications.