Compact and Wide Stopband Lowpass Filter Using Open Complementary Split Ring Resonator and Defected Ground Structure

A compact (0.16 λg x 0.08 λg) and wide stop¬band lowpass filter design using open complementary split ring resonator (OCSRR) and defected ground structure (DGS) is presented in this paper. Low pass filter is con-structed using two cascaded stages of OCSRR. Since the rejection bandwidth of the OCSRR is narrow, tapered dumbbell shaped DGS section is placed under the OCSRR to enhance the bandwidth. The cutoff frequency (fc) of the proposed lowpass filter is 1.09 GHz. The rejection band¬width of the filter covers the entire ultra wideband spec¬trum. Hence the spurious passband suppression is achieved up to 10 fc. The designed filter has been fabri¬cated and validated by experimental result

A Compact Dual Band-Notched Circular Ring Printed Monopole Antenna for Super wideband Applications

In this article, a simple and compact dual band-notched (DBN) super wideband (SWB) printed monopole antenna (PMA) has been proposed. The proposed antenna composed of a circular PMA, which is connected through a 50-Ω triangular tapered microstrip fed line (TTMFL) and a round-cornered finite ground plane (RCFGP). It exhibits a very wide frequency band from 1.6–25 GHz (ratio band¬width of 15.63:1) with a voltage standing wave ratio (VSWR) ≤ 2. By employing a U-shaped parasitic element (USPE) near the RCFGP and a T-shaped protruded stub (TSPS) inside the radiating patch, a single band-notched (SBN) characteristic in the frequency band of 3.2–4.4 GHz (WiMAX/C-band) is generated. In order to realize the sec¬ond band-notched function for X-band satellite communication systems (7.2–8.4 GHz), a U-shaped slot (USS) has been inserted in the RCFGP. The overall dimension of the proposed antenna is 24x30x0.787 mm3 and occupies a relatively small space compared to the existing DBN an¬tennas. Good agreement has been attained between pre¬dicted and measured results

The classical two dimensional Heisenberg model revisited An SU 2 symmetric tensor network study

The classical Heisenberg model in two spatial dimensions constitutes one of the most paradigmatic spin models, taking an important role in statistical and condensed matter physics to understand magnetism. Still, despite its paradigmatic character and the widely accepted ban of a continuous spontaneous symmetry breaking, controversies remain whether the model exhibits a phase transition at finite temperature. Importantly, the model can be interpreted as a lattice discretization of the O 3 non linear sigma model in 1 1 dimensions, one of the simplest quantum field theories encompassing crucial features of celebrated higher dimensional ones like quantum chromodynamics in 3 1 dimensions , namely the phenomenon of asymptotic freedom. This should also exclude finite temperature transitions, but lattice effects might play a significant role in correcting the mainstream picture. In this work, we make use of state of the art tensor network approaches, representing the classical partition function in the thermodynamic limit over a large range of temperatures, to comprehensively explore the correlation structure for Gibbs states. By implementing an SU 2 symmetry in our two dimensional tensor network contraction scheme, we are able to handle very large effective bond dimensions of the environment up to amp; 967;effE amp; 8764;1500, a feature that is crucial in detecting phase transitions. With decreasing temperatures, we find a rapidly diverging correlation length, whose behaviour is apparently compatible with the two main contradictory hypotheses known in the literature, namely a finite T transition and asymptotic freedom, though with a slight preference for the secon