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The sleeve monopole antenna with an integrated broadband filter is presented for base station applications. The antenna is designed to radiate from 698–960 MHz (low band) and provide band rejection from 1695–2690 MHz (high band). The antenna exhibits return loss better than −15 dB in the low band. The filter exhibits excellent rejection where the worst-case return loss is approximately −0.3 dB in...
This paper presents a multiband, electrically small patch antenna with dimensions 147.9 mm by 90.4 mm and an inset microstrip feed. The length of this antenna is suited to a 0.5 GHz resonance. The geometry of the patch has been modified from its traditional form by introduction of five 0.6 mm gaps just inside its outer edge. The effect of these gaps is to reduce the highest frequency of resonance...
This paper presents a dual band, dual polarized rail mount MIMO antenna designed to provide mobile wireless coverage in the stadium environment. The high band (1695–2690 MHz) antenna is a dual polarized vertical printed dipole array with dual slant linear polarization. The low band (698–960 MHz) elements are vertically and horizontally polarized omnidirectional sleeve monopole antennas.
A software-tunable digital non-Foster fast-wave transmission line is presented, using an Internet of Things approach to implement tuning and signal monitoring. Such non-Foster fast-wave lines offer greater bandwidth than conventional passive designs, and a digital non-Foster approach is proposed to provide a software-adjustable implementation of the required negative capacitors. Further, an IoT (Internet-of-Things)...
Measured results are compared to simulation results for a wideband software-adjustable fast-wave line using coaxial line sections loaded with digital discrete-time non-Foster circuit elements. In the proposed approach, the negative capacitance of non-Foster circuit elements is varied by changing the signal processing in the digital non-Foster circuit. For the purposes of demonstration and comparison...
A novel spherical spiral metamaterial unit cell is presented. The structure is shown to provide negative permeability over a 31.7% bandwidth at one orientation with respect to the incident electric field, negative permittivity over a 40.4% bandwidth at a second orientation, and double-negative behavior over a 15.5% bandwidth at a third orientation. At all performance frequencies, the structure is...
An electrically thin magnetodielectric Fresnel zone lens fed with a patch antenna is presented. By using impedance matched magnetodielectric materials to form the lens, the desired focusing can be obtained with very little mismatch loss. The presented lens thickness is one-tenth of a wavelength with alternating regions of free space and material with a refractive index of 6. A metamaterial unit cell...
A digital discrete-time approach is presented for the design of two-port non-Foster circuits. The proposed digital approach offers the potential for effective implementation of complex non-Foster circuits in a wide variety of applications such as wideband metamaterials, broadband impedance matching, electrically small antennas, and artificial magnetic conductors. To illustrate the proposed digital...
The design of a fast-wave microstrip line is presented, where analog negative capacitance circuits are replaced by digital discrete-time non-Foster circuits. Building upon recent results for a wideband three-section fast-wave microstrip line using three negative capacitors, the proposed digital approach is shown to exhibit fast-wave characteristics over wide bandwidth with phase velocity greater than...
A fractal tree monopole antenna is presented. The antenna consists of three iterations of a branching cone pattern over an oblate spheroidal ground. This structure was simulated in Ansys HFSS, and simulation results are given, showing broadband operation beginning at 1.2 GHz and extending beyond 20 GHz. Radiation patterns are shown at 5.5 GHz and at 10 GHz, with co-polarization and cross-polarization...
Measured, simulated, and theoretical results are presented for a unit cell loaded by a non-Foster circuit element comprising a negative capacitor. The unit cell is suspended in the electromagnetic field of a coaxial line for characterization, rather than being directly wired to the transmission line. Relative dielectric constant less than unity was observed over a 5∶1 bandwidth, and supporting theory...
Digital discrete-time implementations of non-Foster circuit elements offer an alternative to conventional analog circuit approaches. In particular, the design of a discrete-time negative capacitor is investigated, since such non-Foster circuit elements offer significant potential in wideband antenna, metamaterial, and artificial magnetic conductor applications. As with analog non-Foster circuits,...
Electrically small resonant scatterers have gained enormous popularity in the field of electromagnetics recently due to their pivotal role in metamaterial design. One of the fundamental physical limitations restricting the application of metamaterials is the inherent narrow bandwidth of the resonators. This paper demonstrates the use of these narrowband scatterers to realize an X-band horn antenna...
There is renewed interest in the use of non-Foster circuit elements in a variety of important applications such as wideband impedance matching and artificial magnetic conductors. Although non-Foster devices such as negative capacitors and negative inductors can be realized using current conveyors and Linvill circuits, a digital design approach may offer an important alternative in some applications...
The primary purpose of the current paper is to design a fast and accurate performance model framework for exploring various thread-to-core mapping strategies (MS) and estimating steady state cycles per instruction (CPI). It is directed towards efficiently exploring these performance metrics for large parallel applications for shared memory multicores. This work establishes a hybrid Markov Chain Model...
A great deal of research has been dedicated to the design and synthesis of metamaterials to acheive interesting electromagnetic properties such as very high, sub-unity, and even negative effective relative permeabilities and permittivities. While the design and fabrication of various metamaterial structures can be a challenge, it can be equally demanding in some cases to make accurate measurements...
A fractal inspired metamaterial structure based on the electric LC resonator (ELC) described in [1] is presented. The proposed unit cell was built with a larger physical size to shift the frequency of operation to lower frequencies, and a partial repetition of the basic I-shape was inserted in each capacitive gap. The resulting structure was simulated in HFSS, and the relative permittivity and permeability...
Current conveyors are useful for creating non-Foster circuit components such as negative capacitors. As with operational amplifiers, it is sometimes desirable to use phase compensation techniques to improve the phase margin and stability in these circuits. However, it is shown for negative capacitor applications that the frequency response in a current conveyor leads to undesired parasitic resistance...
Non-Foster circuits can be used to provide broadband impedance matching for antennas and metamaterials. These circuits allow effective matching over a much wider bandwidth than is expected from traditional passive components. Therefore, this paper considers the design and test of a negative capacitor in a 0.5 micron CMOS process. The proposed circuit uses a cross-coupled design to allow for floating...
This paper presents an effective approach for reducing parasitic resistance of a CMOS negative inductor with a single compensating resistor. A compensating resistor is used to mitigate the effect of parasitic resistance with quadratic frequency dependence. The undesired parasitic effect is induced by the inevitable finite drain-source resistance of the input CMOS transistor of the most common Linvill...
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