Branch Power Ratio Research Articles

A Quad-Band Shared-Aperture Antenna Based on Dual-Mode Composite Quarter-Mode SIW Cavity for 5G and 6G with MIMO Capability

This study introduces a new design for an ultra-compact shared-aperture antenna utilizing a quarter-mode substrate integrated waveguide (QMSIW) cavity. The proposed antenna operates as a 4 × 4 multi-input multi-output (MIMO) system in three 5G/6G millimeter-wave (MMw) bands, while functioning as a single element antenna for a 5.5 GHz wireless fidelity Microwave (Mw) band. The antenna comprises four QMSIW cavity resonators; each QMSIW is loaded with dual slots to produce tri-band MMw operation at 28 GHz, 38 GHz, and 0.13 THz. The four cavities are arranged to reuse the entire aperture by creating a conventional open-loop antenna that operates at a frequency of 5.5 GHz. Simulation, measurement, and co-simulation results show that the proposed antenna has a quad-band operation and exhibits favorable characteristics. The measured scattering parameters validate the simulated ones over the four bands under consideration. The lowest values of the measured total radiation efficiencies are 80%, 73%, 62%, and 72% (co-simulation) within the four covered bands, respectively. The antenna peak gains are 1.8 to 1.85 dBi, 4.0 to 4.5 dBi, 4.3 to 4.5 dBi, and 6.5 to 6.6 dBi within the covered bands. Furthermore, the design satisfies MIMO and diversity conditions (envelope correlation coefficient and branch power ratio) over frequency bands of operation. All excellent results are achieved from an ultra-compact size in terms of footprint area (0.018λ02), where λ0 represents the free space wavelength at 5.5 GHz. The antenna boasts an excellent reuse aperture utilization efficiency (RAU) of 92% and a large ratio frequency of 23, making it an ideal candidate for compact devices. With its superior performance, the proposed design is well-suited for a range ofs wireless communication systems, including mobile devices and the Internet of Things.

Six-port mid-bands Low-SAR MIMO antenna for WLAN, 5G mobile terminals, and C-band applications

This article investigates a six-port multiple-input multiple-output antenna which operates in mid-bands with a resonating frequency at 4.8 GHz. The overall dimensions of proposed antenna are 0.60 λ0×1.32λ0×0.024λ0, where λ0 is free space wavelength corresponding to resonating frequency of 4.8 GHz. The proposed geometry consists of six-port electromagnetic wave components along with a plane rectangular patch, slotted partial ring ground, circular cutting ground plane, and inset feeding. For enhancing isolation, I-shaped stubs and slotted ring ground are responsible. Inset feeding, circular cutting ground plane, and partial ground plane are used for enhancing reflection coefficient. The overall −10 dB impedance bandwidth of proposed antenna is ranging from 3.92 GHz to 5.2 GHz. The achieved isolation between all the ports of proposed work is ¿15 dB. The peak values of gain and radiation efficiency provided by this prototype are 6.45 dB & and 86% respectively. The achieved diversity parameters such as envelope correlation coefficients are ¡0.002, diversity gain is 9.98, channel capacity loss is ¡0.014 bits/sec/Hz, and branch power ratio is ¡−1 dB. The proposed antenna can be considered as a suitable candidate for wireless local area network, n77 bands, 5G wireless communications applications, and C-band operations.

Experimental Evaluation of User Influence on Test Zone Size in Multi-Probe Anechoic Chamber Setups

Over-the-air (OTA) radiated testing for multiple-input multiple-output (MIMO) capable mobile terminals has been actively discussed in the standardization in recent years, where multi-probe anechoic chamber (MPAC) method has been selected, together with the radiated two-stage method. The supported test zone size is a key parameter to determine for an MPAC design, and the test zone size is restricted by the number of OTA antennas. A larger test zone would necessitate more OTA antennas, each port of which is driven by an expensive channel emulator radio frequency interface. Results available in the literature are typically limited to free space scenarios, where no user effect in the vicinity of MIMO terminal is present. There is a concern whether or not the test zone size should encompass the user phantom, together with the mobile terminal in the MPAC setup. To address this issue, an extensive measurement campaign was carried out in this paper. Two realistic long term evolution mockups were designed and their performance were evaluated under standard spatial channel models with and without the presence of user phantom. The measurement results have shown that the nearby user phantom can significantly affect the MIMO performance. However, its impact on the test zone size of the MPAC system is negligible, since emulation accuracy in terms of received power, branch power ratio, antenna correlation, and measured throughput under the target and the emulated channels is not affected by the presence of user phantom. Moreover, results measured with the synthetic MPAC method generally match those obtained with the reference two-stage method. These findings are valuable inputs for the ongoing MIMO OTA harmonization work in the standardization.

A Port and Frequency Reconfigurable MIMO Slot Antenna for WLAN Applications

A novel compact four-port reconfigurable multiple-input multiple-output (MIMO) antenna design for IEEE 802.11 applications is proposed. In one configuration, the antenna provides four ports operating from 4.9 to 5.725 GHz with isolation between antennas greater than 14 dB. In the second configuration, it provides a two-port antenna operating at 2.4–2.5 GHz together with another two-port antenna operating at 4.9–5.725 GHz all with isolations greater than 18 dB. The structure consists of four-slot antennas, and two of the slots are made reconfigurable by including MEMS switches in the slots. The overall antenna size is compact and occupies $46\times20\times1.6\;{\rm mm}^{3}$ and is printed on FR-4 printed-circuit-board. The proposed antenna is investigated by simulation and measurement, and results include radiation patterns, S-parameters, and signal correlations and branch power ratio (BPR) between ports. These show that in typical wireless environments’ envelope, cross correlations of less than 0.2 between the ports are obtained. The effect of the RF MEMS switches on the antenna performance is also addressed.

Investigation of a Triple-Band Multibeam MIMO Antenna for Wireless Access Points

A triple-band multibeam multiple-input multiple-output (MIMO) antenna is investigated for access points (APs). The triple-band antenna covers 2.4–2.5, 3.4–3.7, and 5.1–5.9 GHz frequency bands with high gains and directional radiation patterns for WLAN/WiMAX applications. The MIMO antenna consists of four triple-band antenna elements rotated around a circle for space and polarization diversities. The multibeam antenna is composed of four MIMO antenna units for the coverage of a conical area. The triple-band multibeam MIMO antenna is designed and the MIMO performance is evaluated. It is shown that low capacity loss and high diversity gain can be obtained with the low correlation and low branch power ratio between the MIMO antenna units. It is found that the four-beam MIMO antenna is suitable for large public places with high density clients where enhanced frequency reusability and reduced maintenance efforts are preferred.

On Antenna Design Objectives and the Channel Capacity of MIMO Handsets

The branch correlation coefficient (BCC), the branch power ratio (BPR), and the total mean power (TMP) are often used to characterize the mobile multiple-input multiple-output (MIMO) channel. This work investigates to which degree these parameters are useful for maximizing the channel capacity of multiple-input multiple-output (MIMO) handheld devices used in data mode. A statistical point of view is applied, using about 2800 outdoor to indoor channel sounder measurements obtained with combinations of ten different handsets, four to eight test users, and a variety of different use cases (UCs). All measurements were made in an urban environment in a setup with two different base stations (BSs) and with the users inside a single building. For each measurement combination, the mean capacity (MC) and associated values of BCC, BPR, and TMP are obtained. From the data it is found that the MC is only weakly correlated with both the BCC and the BPR, while the MC is highly correlated with the TMP.

MIMO Reference Antennas Performance in Anisotropic Channel Environments

The new generation of cellular wireless communications, long term evolution (LTE), requires multiple antennas at both the transmit and receive ends of the radio link to improve system performance. This use of the radio link is termed multiple input-multiple output (MIMO), and in this work, the focus is on the downlink (base station transmit and mobile receive). Efforts to define over-the-air (OTA) downlink MIMO measurement methodologies are still being carried out within several standards bodies and are based on the evaluation of so-called good, nominal, and bad MIMO reference antennas. The reference antennas were necessarily defined independently of the channel environment, which is still under discussion. The reference antenna figures of merit, for an isotropic channel environment, were chosen as efficiency, branch power ratio (BPR), and correlation. The objective of this work is to evaluate the radiated performance of the MIMO reference antennas using anisotropic (nonuniform power angular spread) channel environments. The performance of the reference antennas in anisotropic environments is different to that in an isotropic environment, due to the antenna orientation in the three-dimensional space relative to the channel. This leads to a statistical description of the branch power ratio (BPR), correlation, and efficiency, which is expressed in terms of mean effective gain (MEG). The outcome of this new anisotropic evaluation is that the reference antennas are seen to vary significantly for BPR and mean effective gain (MEG) and somewhat less for correlation, relative to the isotropic environment.

Experimental interference assessment between two independent and simultaneous 4 × 4 MIMO handset user links operating at 5 GHz

Analysis of simultaneous 4 × 4 MIMO channel measurements at 5 × GHz are discussed that evidence the impact of user interaction on mobile terminals that will significantly impact the signal to interference ratio between two users. Results indicate that branch power ratio on a mobile, which results from user interaction, will impact both its interference to other users but also its own signal to interference ratio. User interactions both in talk position and texting position are considered.

MIMO capacity dependence on realistic cross‐polarization and branch power ratios

AbstractThe dependence of channel capacity on cross‐polarization and the branch power ratio is established over a wide range of both realistic and idealized values. An existing empirical model is adjusted to avoid self‐contradictory results for cross‐coupled, but uncorrelated energy. Typical ranges are highlighted for realistic channel measurements from the literature, and extreme cases are identified. The value of a peak capacity measure is established and compared with the outage and average capacities. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 1384–1388, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23360

Propagation Modeling of MIMO Multipolarized Fixed Wireless Channels

This paper addresses the extension of a stochastic geometry-based scattering model to multipolarized transmissions. The initial approach is based on a geometrical distribution of obstacles derived from known power-delay profiles. Each scattering process is statistically described by a matrix reflection coefficient corresponding to dual-polarization states. Ultimately, the model allows us to simulate the effects of the range on K-factor, delay-spread, Doppler spectrum, channel correlations and capacity, branch power ratio, and cross-polar discrimination. Simulation results are compared with existing measurements at 2.5 GHz. The proposed model is then used to investigate various dual-polarization 2 /spl times/ 2 multiple-input-multiple-output (MIMO) schemes such as 0/spl deg//90/spl deg/ or /spl plusmn/45/spl deg/, as well as to optimize the design of multipolarized MIMO schemes.

Spherical outdoor to indoor power spectrum model at the mobile terminal

Mobile terminals are often used indoor with the base station outdoors. At the mobile terminal the major part of the signal energy comes through openings in the building such as windows. Typically, only one of the sides in a room has windows, and seldom does a room have windows on all sides. Hence, the dominating signal can be expected to arrive at the mobile terminal from a narrow range of angles. Mobile terminal antennas used next to the head in the speaking position will be directional due to the fact that part of the radiation pattern facing the head will be attenuated and reflected. Having a directive antenna in a directive environment, the performance will depend on the orientation of the antenna in the radio environment. A new statistical spherical outdoor to indoor power spectrum model has been proposed to be able to calculate the directional performance of mobile terminals with a single or multiple antennas. The model consists of a major scattering area in one direction and more uniformly distributed minor scatterers in the other directions. A verification of the proposed model was performed and 60 data sets of spherical power spectrum measurements were collected in a typical urban environment. Using the new model, the directional performance of mobile terminal antennas including a human operator has been investigated through directional mean effective gain, branch power ratio, and correlation calculations using spherical radiation pattern measurements of a mobile terminal including the effect of 42 different persons. The accuracy of the calculated values was verified by directly measured values using 200 persons walking with the mobile terminal in the same office-like environments as where the spherical power spectrum measurements were performed.