Ultra Wideband Signals and Systems in Communication Engineering

Cognitive radios have been proposed as a means to implement efficient reuse of the licensed spectrum. The key feature of a cognitive radio is its ability to recognize the primary (licensed) user and adapt its communication strategy to minimize the interference that it generates. We consider a communication scenario in which the primary and the cognitive user wish to communicate to different receivers, subject to mutual interference. Modeling the cognitive radio as a transmitter with side-information about the primary transmission, we characterize the largest rate at which the cognitive radio can reliably communicate under the constraint that (i) no interference is created for the primary user, and (ii) the primary encoder-decoder pair is oblivious to the presence of the cognitive radio.

Cognitive Radio: An Information-Theoretic Perspective

Koch-shaped dipoles are introduced for the first time in a wideband antenna design and evolve the traditional Euclidean log-periodic dipole array into the log-periodic Koch-dipole array (LPKDA). Antenna size can be reduced while maintaining its overall performance characteristics. Observations and characteristics of both antennas are discussed. Advantages and disadvantages of the proposed LPKDA are validated through a fabricated proof-of-concept prototype that exhibited approximately 12% size reduction with minimal degradation in the impedance and pattern bandwidths. This is the first application of Koch prefractal elements in a miniaturized wideband antenna design.

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A Printed Log-Periodic Koch-Dipole Array (LPKDA)

This paper presents compact size 4 × 4 cm 2 MIMO antenna for UWB applications. The proposed antenna consists of four symmetric circular elements printed on low cost FR4 substrate with partial slotted ground plane. The two sides of the substrate are symmetric and each side is consisting of two radiators with the partial ground planes associated to the two other elements mounted on the other side. The two elements of the front side are orthogonal to the two other elements of the back side in order to increase the isolation between elements. For further reduction in the mutual coupling between elements, decoupling structures are presented in the top and bottom layers of the substrate. The simulated and measured results are investigated to study the effectiveness of the MIMO-UWB antenna. The results demonstrate the satisfactory performance of MIMO-UWB antenna, which has a return loss less than −10 dB from approximately 3.1 GHz to more than 11 GHz with an insertion loss lower than −20 dB through the achieved frequency band, and a correlation less than 0.002. Moreover, the proposed MIMO model exhibits a nearly omni-directional radiation pattern with almost constant gain of average value 3.28 dBi.

A compact double-sided MIMO antenna with an improved isolation for UWB applications

A compact tree shape planar quad element Multiple Input Multiple Output (MIMO) antenna bearing a wide bandwidth for 5G communication operating in the millimeter-wave spectrum is proposed The radiating element of the proposed design contains four different arcs to achieve the wide bandwidth response Each radiating element is backed by a 157 mm thicker Rogers-5880 substrate material, having a loss tangent and relative dielectric constant of 00009 and 22, respectively The measured impedance bandwidth of the proposed quad element MIMO antenna system based on 10 dB criterion is from 23 GHz to 40 GHz with a port isolation of greater than 20 dB The measured radiation patterns are presented at 28 GHz, 33 GHz and 38 GHz with a maximum total gain of 1058, 887 and 1145 dB, respectively The high gain of the proposed antenna further helps to overcome the atmospheric attenuations faced by the higher frequencies In addition, the measured total efficiency of the proposed MIMO antenna is observed above 70% for the millimeter wave frequencies Furthermore, the MIMO key performance metrics such as Mean Effective Gain (MEG) and Envelope Correlation Coefficient (ECC) are analyzed and found to conform to the required standard of MEG < 3 dB and ECC < 05 A prototype of the proposed quad element MIMO antenna system is fabricated and measured The experimental results validate the simulation design process conducted with Computer Simulation Technology (CST) software

https://www.mdpi.com/2079-9292/9/6/1031/pdf

A Novel High Gain Wideband MIMO Antenna for 5G Millimeter Wave Applications

A compact dual-frequency ( 38 / 60 GHz ) microstrip patch antenna with novel design is proposed for 5G mobile handsets to combine complicated radiation mechanisms for dual-band operation. The proposed antenna is composed of two electromagnetically coupled patches. The first patch is directly fed by a microstrip line and is mainly responsible for radiation in the lower band ( 38 GHz ). The second patch is fed through both capacitive and inductive coupling to the first patch and is mainly responsible for radiation in the upper frequency band ( 60 GHz ). Numerical and experimental results show good performance regarding return loss, bandwidth, radiation patterns, radiation efficiency, and gain. The impedance matching bandwidths achieved in the 38 GHz and 60 GHz bands are about 2 GHz and 3.2 GHz , respectively. The minimum value of the return loss is − 42 dB for the 38 GHz band and − 47 for the 60 GHz band. Radiation patterns are omnidirectional with a balloon-like shape for both bands, which makes the proposed single antenna an excellent candidate for a multiple-input multiple-output (MIMO) system constructed from a number of properly allocated elements for 5G mobile communications with excellent diversity schemes. Numerical comparisons show that the proposed antenna is superior to other published designs.

https://www.mdpi.com/1424-8220/20/9/2541/pdf

A Novel Dual-Band (38/60 GHz) Patch Antenna for 5G Mobile Handsets

This paper presented the design and implementation of a 60 GHz single element monopole antenna as well as a two-element array made of two 60 GHz monopole antennas. The proposed antenna array was used for 5G applications with radiation characteristics that conformed to the requirements of wireless communication systems. The proposed single element was designed and optimized to work at 60 GHz with a bandwidth of 6.6 GHz (57.2–63.8 GHz) and a maximum gain of 11.6 dB. The design was optimized by double T-shaped structures that were added in the rectangular slots, as well as two external stubs in order to achieve a highly directed radiation pattern. Moreover, ring and circular slots were made in the partial ground plane at an optimized distance as a defected ground structure (DGS) to improve the impedance bandwidth in the desired band. The two-element array was fed by a feed network, thus improving both the impedance bandwidth and gain. The single element and array were fabricated, and the measured and simulated results mimicked each other in both return loss and antenna gain.

A Novel High Gain Monopole Antenna Array for 60 GHz Millimeter-Wave Communications

In this paper a low cost rectangular ring monopole antenna element and antenna array with parasitic patches are presented for ultra-wideband applications. The proposed antenna element and antenna array are constructed with a modified partial ground plane on FR4 epoxy substrate with relative permittivity 4.4 and thickness 1.5 mm. A parametric study on the main parameters of the radiating elements and the distance between them as well as the partial ground has been investigated to optimize the design of the antenna array. The return loss is less than −10 dB in the frequency range 3.6–9.6 GHz which makes it suitable for UWB applications. Impedance and radiation characteristics of the proposed antenna are simulated using Ansoft HFSS 13 software. The simulated and measured results show good agreement and validate the proposed approach. © 2016 Wiley Periodicals, Inc. Microwave Opt Technol Lett 58:2268–2273, 2016

Design and fabrication of rectangular ring monopole array with parasitic elements for UWB applications

Recently, genetic algorithm/method of moments (GA/MoM) technique is used as an efficient optimization tool for many antenna design problems. In this paper, a GA/MoM code is developed and used for compressing the size of the wideband log-periodic dipole array (LPDA). The numerical simulations prove that the optimized LPDA with compressed dimensions has nearly the same characteristics of the previously published designs. The optimized LPDA is then applied to a Cantor fractal array design and a multiband behavior is obtained successfully.

http://ieeexplore.ieee.org/iel5/10444/33168/01562507.pdf

Amira I. Zaki

Papers

A Novel Dual-Band (38/60 GHz) Patch Antenna for 5G Mobile Handsets

A Novel High Gain Monopole Antenna Array for 60 GHz Millimeter-Wave Communications

Design and fabrication of rectangular ring monopole array with parasitic elements for UWB applications

Genetic algorithm design of compressed log periodic dipole array

A new fractal‐like tree structure of circular patch antennas for UWB and 5G multi‐band applications