Quad-Element Implantable MIMO Antenna for Wireless Capsule Endoscopy.

To meet the 5G communication requirements for smartphone terminal antennas regarding element count and isolation, this paper proposes a 12 -element MIMO antenna with shared radiators for 5G smartphones. The <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$12 \times 12$</tex> MIMO antenna consists of six shared-radiator antenna pairs symmetrically distributed on both sides of the substrate. Each radiator is directly excited by two feeding ports and comprises a rectangular radiating strip on the inner side of the side frame along with two L-shaped grounded radiating strips printed on the outer side. The overall dimensions of the 12-element MIMO antenna system on the side frame are <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$30 \text{mm} \times 3.2 \text{mm} \times 12$</tex>, demonstrating a compact structure. The L-shaped radiating strips printed on the outer side enhance impedance matching performance and extend bandwidth. Simultaneously, a rectangular grounding strip printed between the rectangular radiating strip and the ground plane improves common-mode currents. Assisted by this grounding strip, the antenna pair achieves self-decoupling through mode cancellation based on common-mode and differential-mode synthesis. The proposed shared-radiator antenna pair exhibits excellent isolation exceeding 11.9 dB within the operating bandwidth (3.95-5.25 GHz) and features radiation pattern diversity. Moreover, the <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$12 \times 12$</tex> MIMO antenna formed by these antenna pairs achieves high channel capacity and operates within the 3.95-5 GHz bandwidth (below −10 dB in <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$S_{11})$</tex>, covering the n79 band. Based on the shared-radiator antenna pair design, this architecture achieves self-decoupling and constructs a <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">$12 \times 12$</tex> MIMO antenna system. This MIMO system demonstrates high channel capacity while featuring a novel structure, straightforward architecture, and wide bandwidth. The proposed design exhibits significant application potential for highly integrated MIMO antennas in future 5G smartphones.

As discussed in the previous chapter, Low Power Communication is the key to realization of a low power sensor node. Since sensor nodes require only low data rate communication, it might sound intuitively clear that they should also naturally be low power. After all, if a node does less work, it should also consume lesser power. But somehow this doesn’t seem to fit the behavior for low data rate communication, short range radios. If we look at existing radio designs at various data rates and ranges, we see that the design space occupied is very wide. There are designs that operate at very high (~100 Mbps) data rates and designs that operate at low data rates (~100 Kbps). There are designs that take wall supply, consuming a few watts of power, while some work on batteries. If one looks at energy per bit requirements of these designs, while some designs operate at hundreds of nJ/bit, some other designs exist consuming only 0.1 nJ/bit (Fig. 2.1). Now if we plot the range over these designs and examine how they should scale according to the energy/bit requirements we should see radios working at low data rates while consuming few microwatts of power, as required by sensor networks. These designs do not exist. The reasons there aren’t any designs in this space requires us to consider the consequences of scaling traditional design as we go for lower and lower data rate. Since Shannon’s law governs the limit on the energy efficiency of radio communication and link margin vis-à-vis the channel capacity, it makes sense to have a closer look at it and then see what constraints typical radio architectures have that prevent power from scaling in low data rate applications.KeywordsSensor NodeSpectral EfficiencyLeakage PowerGain StageImpulse RadioThese keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.

In this article, a novel metasurface absorber is designed for RCS reduction as well as high isolation in a 4-elements MIMO antenna. A unit cell of metasurface absorber is amalgamated by concentric circular and elliptical-shaped rings with four 300 ohms lumped resistances. Absorbance at the intended frequency band (i.e. 8.75 GHz-9.00 GHz) of metasurface absorber is more than 90.0% and its reflectivity is tending to zero. Therefore, the isolation between antennas due to this absorbance is improved by 12 dB, and the total isolation of the antenna is achieved less than 23 dB. Similarly, the Radar cross-section (RCS) of the antenna is also significantly reduced by 10dBm2. This MIMO antenna with an absorbing structure is fabricated on a richly existing FR4 substrate with dimensions of 55 × 40 × 1 mm3. The performance of the designed MIMO antenna is also judged by diversity parameters similar to Envelope correlation coefficient (ECC), Directive gain (DG), Mean effective gain (MEG), Channel capacity loss (CCL), Total Active Reflection Coefficient (TARC), and channel capacity, etc. for the proposed frequency band. The simulated and measured ECC of the proposed MIMO is less than 0.073 which exhibits that this antenna is suitable for military application in radiolocation and navigation.

SummaryA small size neutralization line integrated flower‐shaped MIMO antenna is designed and analyzed for sub‐6 GHz type 5G NR frequency bands like n79 (4400–5000 MHz), n78 (3300–3800 MHz), n77 (3300–4200 MHz), and WLAN (5150–5825 MHz) applications. The novel approach of theory of characteristic mode analysis (TCMA) is introduced to provide physical insight of the designed structure and its characteristics behavior. Due to the suggested modifications in the geometry, the isolation among the patches is greatly increased. The overall miniaturized dimension of the MIMO antenna is 25 × 40 mm2. The edge‐edge spacing among the elements is 0.0233λ. The prototype antenna is fabricated and measured that shows good agreement compared with simulated results. The designed MIMO antenna without the presence of decoupling structure offers an isolation of 28 dB, gain of 3.6 dBi, and radiation efficiency of 69.7% at the resonant frequency. The proposed MIMO antenna covers a broad range of frequency band from 3.296 to 5.962 GHz with −10 dB impedance bandwidth of 2666 MHz and maintains a good isolation of greater than 50 dB for the entire operating band. The tested radiation efficiency and gain are 85.3% and 6.22 dBi at 3.5 GHz. Moreover, the diversity parameters of the neutralization line integrated MIMO antenna, that is, channel capacity loss (CCL) isolation, mean effective gain (MEG), total active reflection coefficient (TARC) diversity gain (DG), and envelope correlation coefficient (ECC), are analyzed and discussed in this article.

A four-element, compact, ultra wide band antenna for multi-input-multi-output (MIMO) applications, is proposed in this paper. The proposed MIMO structure consists of four identical monopole elements that are placed perpendicular to each other to achieve the pattern diversity among them. The proposed structure gives an advantage of high isolation and low correlation; however, to improve this isolation more, stubs are used and placed in the front layer of the substrate. The proposed antenna has a compact size of area 42 x42 mm2 and has a frequency range from 3.2 to 12 GHz which is suitable for UWB applications. The antenna characteristics such as the bandwidth, isolation, peak gain, diversity gain, and envelope correlation coefficient are studied through simulation and fabrication. The fabricated antenna measurements show that the proposed MIMO antenna has a large bandwidth of nearly 9 GHz over the range from 3.2 to 12 GHz, with a low correlation coefficient <0.01 and high isolation of 17dB in the operated band of frequency. The simulation and measurement results are introduced and there is an agreement between them.

An ultra-wideband (UWB) dual-polarized microstrip slot antenna with high port isolation and planar structure is presented in this letter. This antenna consists of a monopole and a tapered microstrip feed line, they are used for obtaining UWB characteristic and generating two orthogonal polarization modes. Furthermore, the good impedance matching can be attained through etching slots on the ground plane. The simulated results point out that the antenna can cover the input impedance bandwidth of 3.1∼10.6 GHz with reflection coefficient <−10 dB, and the port isolation is better than 22 dB over the whole operating band. It also has a good radiation performance and is appropriate for UWB applications.

Background. Previously, Many MIMO designs were presented for 4G applications. Out of stated 4G MIMO antennas, few designs presented are not suitable for use in mobile phones due to their large size as compared to the standard sizes of current generation mobile phones. The rest, Ceramic based mobile phone antenna and a multi-band MIMO antenna with PIFA structures have significant heights and non-planner structure which makes them unsuitable for mobile phones as they are getting thinner with advancement in technology. Some MIMO antennas were designed with simpler structure and suitable size but they do not have adequate bandwidth. Here there is a need to develop a MIMO system with an adequate bandwidth to cover all 2G, 3G and 4G bands as well as compact to be suitable for mobile communication.Objective. The purpose of the paper is to design a compact planner MIMO antenna Suitable for Mobile communication with enhanced gain and an enhanced bandwidth to cover all 2G, 3G and 4G bandsMethods.i. A monopole was designed with proper dimensions, which was designed to operate at focus recurrence of 1.8GHz. That covers the wide scope of data transfer capacity from 1.1 GHz to 2.7 GHz at -9 dB reference line. Then an inverted L shape structure known as SIR stub technique is used to enhance the bandwidth.ii. The inverted L shape structure which is extended from the ground plane is put around the monopole which generates the low resonant frequencies and also broadens the bandwidth. Bandwidth is broadened to 0.8 GHz to 3.5 GHz.iii. For the purpose of more impedance matching, a small patch is etched from the ground plane opposite to the feeding and all the parameters are optimizedResults. that lower 0.9GHz radiation pattern is omnidirectional while at higher frequencies it is quasiomnidirectional, a steady gain greater than 2.8dBi over the entire frequency band i.e from .8 GHz to 3.5 GHz, avery high gain of 6.7 dBi at 0.9 GHz. The compact wide band planar MIMO antenna has over 80% efficiency over most of the working recurrence For handy application ECC value less than 0.5 is adequate for mobile phones. The measured ECC is less than 0.36 over complete operating frequency band, which is all right for mobile phonesConclusions. The paper presents compact planner two port MIMO antenna with wideband width and high gain. The proposed antenna achieved a wide bandwidth from 0.8GHz to 3.5GHz covering 2G/3G/4G bands and Wi-Fi (2.45GHz). High isolation between antenna elements, lower ECC and high diversity gain makes the design of the compact planner wide band MIMO antenna a suitable possibility for mobile phone applications.

We propose a low-cost, dual band (2.4–5.2 GHz) and dual band (2.4–5.8 GHz) MIMO antennas by using two identical T shaped antenna with high isolation. MIMO is a technique that is used a multiple number of antennas as a transmitter and a receiver. Using artificial magnetic conductor as a reflector made our antenna low profile and high isolated. A dual-band MIMO antenna with high isolation by using artificial magnetic conductor (AMC) is proposed.

Orthogonal frequency-division multiplexing (OFDM) signaling format is commonly associated with guard subintervals to reject interblock interference (IBI) and enable simple one-tap frequency-domain equalization (FDE) at the receiver when received over dispersive channels. Despite the advantages, the insertion of guard subintervals expands the signal spectrum and thus trades off the spectral efficiency significantly. In this paper, the nonguarded OFDM (NG-OFDM) signaling format, which is exactly OFDM without inserting guard subintervals, is considered to avoid the spectrum expansion and combined with spectral precoding to further achieve high spectrum compactness. In particular, spectral precoders are designed for NG-OFDM to provide very small spectral sidelobes, and thus extremely compact signal spectrum, and associate the transmitted waveform with low peak-to-average power ratio. To reject IBI among received NG-OFDM blocks over dispersive channels, a guard subinterval in each received block is removed at the receiver, and this turns the resultant receiver as nonorthogonal over subcarrier subchannels, thus resulting in intercarrier interference (ICI). The corresponding channel capacity and linear minimum-mean-square-error (LMMSE) data estimation are analyzed. It is shown that the proposed spectrally precoded NG-OFDM (SP-NG-OFDM) system can provide channel capacity very close to nonprecoded and spectrally precoded OFDM using the cyclic prefix (CP-OFDM) when the removal guard ratio is small, and much higher channel capacity per unit bandwidth than spectrally precoded CP-OFDM conveying the same data rate provided that a small out-of-band power proportion is required. When a sufficiently small precoding rate is adopted, the SP-NG-OFDM receiver, using guard removal and LMMSE-FDE, is also shown to counteract ICI effectively and exploit frequency diversity over dispersive channels.

In line of sight multiple input multiple output (LoS-MIMO) transmission in a feeder link, which involves communication between a ground station and a high altitude platform station (HAPS), the design of antenna arrays that ensure a stable and high channel capacity is a challenge because of the degradation of the channel capacity caused by changes in the distance and angle owing to the movement of the HAPS. In this study, we first evaluate the channel capacity characteristics of a basic uniform linear array (ULA) for LoS-MIMO transmission during movement. To compensate for this drawback, we propose a uniform cross array (UXA) configuration with two crossed ULAs as the antenna array and show that the LoS-MIMO transmission with the UXA configuration is robust against HAPS movement. The method in this paper is applicable to HAPS as well as LoS-MIMO transmission between two stations with changing positions. LoS-MIMO transmission using UXA exhibits excellent performance with the channel capacity approaching the theoretical upper bound.

We propose a high-gain, multi-wideband Dielectric Resonator Antenna (DRA) utilizing an orthogonality technique to minimize interference and noise, achieving a low correlation coefficient. Operating across X, Ku, K, and Ka bands, the design incorporates a Defected Ground Structure (DGS) with two cylindrical and two semi-circular cuts, alongside a hybrid DRA with horizontal and vertical cuts. A microstrip feed enhances impedance matching, controls electric field distribution, and increases bandwidth, ensuring optimal performance across the targeted frequency bands. The antenna operates at four resonant frequencies: 12.6 GHz, 18.1 GHz, 30.5 GHz, and 40.4 GHz, with good impedance matching and bandwidths of 11.11%, 42.92%, 18.42%, and 14.18%, respectively. Transmission coefficients are below -30.41 dB, - 33.74 dB, -26.74 dB, and -29.66 dB. The achieved gains are 5.78 dB, 6.23 dB, 7.51 dB, and 8.19 dB, with radiation efficiencies exceeding 97% across all bands. Axial ratios remain below 3 dB, with values of 1.652 dB at 18.62 GHz and 1.746 dB at 40.4 GHz. Low Envelope Correlation Coefficients (ECC) of 0.0004 to 0.002 ensure minimal interference. This antenna is ideal for satellite communications, military aircraft, defense tracking, and radar systems.

A novel compact microstrip MIMO antenna with high isolation and low envelope correction coefficient has been proposed and presented in this paper. The proposed antenna is compact in size with 3.22x4.86 mm2, operating over the frequency band of 60GHz. The MIMO antennas have been designed andsimulated using electromagnetic design and verification platformIE3DTM. Two ports MIMO antenna with the size of 3.22x1.93 mm2 resonates at 58.1 GHz covering a band of 57-59.3 GHz, with the bandwidth of 2.3 GHz, gain of 5.2 dBi, and directivity of 8.67 dBi. It also provides aninput reflection coefficient of -18.41 dB with isolation of -19.98 dB. Proposed four port MIMO antenna resonates at 58 GHz covering a range of 56.9 GHz to 59.2 GHz, with a bandwidth of 2.3 GHz, gain of 5.44 dBi, and the directivity of 9.75dBi. It provides goodisolationranging from -19 dB to -30 dB with input reflection coefficient of -18.09 dB. The envelope correlation coefficient (ECC) of the proposed four-port MIMO antenna is below 0.06 in far-field radiation characteristics. The proposed MIMO antenna has been analyzed for its diversity performance in terms of ECC, mean effective gain, and diversity gain.

Relative comparison of the effective isotropic radiated power (EIRP) from Fleet Satellite (FLTSAT) against the UHF Follow-On (UFO) satellites generally shows equal or reduced downlink signal power from the UFO transponders, far less than the anticipated 3.5 dB increase in specified narrowband channel EIRP. Thus we have a relative measurement between what the warfighter sees today (FLTSAT) and what the future holds (UFO). Understanding of this measurement is key to the expected UHF SATCOM performance over the next decade as the UFO constellation replaces aging FLTSAT satellites. Certainly narrowband (5 kHz) channel spacing has improved with the advent of UFO, allowing an increase in transponder channel bandwidth. Wideband (25 kHz) channels have also increased in bandwidth, inviting the use of higher data rate modulation. Link margin is even more important today because of increased emphasis on higher data rates and the migration of terminals to on-the-move (OTM) operation with lower-gain, hemispherical-coverage antennas. Mobile SATCOM users however will not be able to take advantage of this increased data throughput, due to low link margins. Technological advances are required of SATCOM terminals to mitigate low carrier-to-noise (C/N) signals available at the antenna forward error coding (FEC) provides some improvement in data integrity at the cost of decreased data rates. However, if the link margins become too low during multipath fading, the terminal becomes synchronization-limited. Several techniques are available which provide significant improvement over the traditional Costas tracking and synchronization loops. These include mod-remod, data-aided, parallel loops and simultaneous clock/carrier synchronization. The MOST (multiple output SATCOM transceiver) terminal, for example, utilizes advanced software algorithms to provide acquisition and tracking for reduced C/N signals. Measured results show a 5 dB improvement in acquisition compared to traditional SATCOM terminals.

Radiation patterns for a Uniform Linear Array deployed in millimeter wave communications are analyzed. Millimeter wave technology works on extremely high frequency bands such as 28, 38, and 72 GHz bands which results in reduced antenna height. The sizes of these antennas lie in the range of millimeters and therefore they are assembled on-chip. These can further be steered to obtain high directivity and channel capacity. Directed antennas are implemented using beamsteering in millimeter wave communications for achieving higher data rates and thereby higher capacity. The data rates are reported to increase by around 40 times as compared to off-chip antennas. In this paper, beam patterns for a uniform linear array are observed for varying number of elements and varying spacing between two antennas. Performance analysis is done in terms of Array Gain and Half Power Beamwidth.

A compact four-element multiple-input-multiple-output (MIMO) antenna for ultra-wideband (UWB) applications with WLAN band-notched characteristics is proposed here. The proposed antenna has been designed to operate from 2 to 12 GHz while reject the frequencies between 4.9 to 6.4 GHz. The four antenna elements are placed orthogonal to attain the polarization diversity and high isolation. A thin stub connected to the ground plane is deployed as a LC notch filter to accomplish the rejected WLAN band in each antenna element. The mutual coupling between the adjacent elements is at least 17 dB while it has low indoor and outdoor envelop correlation (<0.45) and high gain with compact size of two boards, each measuring 50 × 25 mm2. To validate the concept, the prototype antenna is manufactured and measured. The comparison of the simulation results showed good agreement with the measured results. The low-profile design and compact size of the proposed MIMO antenna make it a good candidate for diversity applications desired in portable devices operating in the UWB region.