Relationship between radiation pattern correlation and scattering matrix of lossless and lossy antennas

Stjernman, Anders

doi:10.1049/el:20050988

Cited by 43 publications

(37 citation statements)

References 3 publications

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“…6 and 7 respectively. The calculations with equivalent circuit (red solid line) were obtained with (3) and (2). It has to be emphasized, that the data rely solely on the raw S-parameter measurements and have neither been interpolated nor postprocessed in any other way.…”

Section: A Efficiencies From Equivalent Circuit Wc Methodsmentioning

confidence: 99%

“…8. This antenna, although not practical for real life communication systems, was proposed in [2] as a testbed for MIMO correlation, as it offers a unique combination of highly correlated patterns and low S 21 coupling. The monopole antenna itself has very high efficiency, but due to the Wilkinson divider the total efficiency cannot exceed 0.5.…”

Section: Validation With Wilkinson Dividermentioning

confidence: 99%

“…This evaluation requires to measure a full-sphere radiation pattern for each port, what is time consuming and requires expensive facilities, not available to many small industries. However, an alternative technique was proposed by Hallbjorner in [1], whereassuming uncorrelated losses in both antennas -one can calculate the ECC based solely on S-parameters and radiation efficiencies η 1 and η 2 : Measurement of antenna's efficiency is a challenging task, however ignoring the losses will yield a huge mistake in (1), as demonstrated in [1][2][3][4]. A convenient technique to overcome this difficulty could be a Wheeler Cap.…”

Section: Introductionmentioning

confidence: 99%

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On the use of wheeler cap for MIMO antennas

Reher

Narbudowicz²,

Ammann³

et al. 2017

2017 11th European Conference on Antennas and Propagation (EUCAP)

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Abstract-A new equivalent circuit based Wheeler Cap method to calculate MIMO efficiency is introduced. The method works without the necessity for interpolation by avoiding concur of resonating and cavity modes. The method is tested with a set of three differently correlated MIMO antennas. Results are compared with the recently proposed quality factor method for MIMO antennas and efficiency data from spherical near field measurements.

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Section: A Efficiencies From Equivalent Circuit Wc Methodsmentioning

confidence: 99%

Section: Validation With Wilkinson Dividermentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

On the use of wheeler cap for MIMO antennas

Reher

Narbudowicz²,

Ammann³

et al. 2017

2017 11th European Conference on Antennas and Propagation (EUCAP)

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show abstract

“…To solve this problem, based on the relationship between the antenna patterns and scattering parameters [5], several researchers have tried to simplify the process of calculating the ECC using S-parameters, instead of the 3D radiation patterns [6][7][8].…”

Section: Introductionmentioning

confidence: 99%

“…However, the ECC calculated using the equation in [6] is much lower than the actual value when the targeted small MIMO mobile antenna operates in a low-frequency range, typically below 1 GHz, because the antenna elements have low efficiency, and a large portion of the energy is radiated from the ground plane [12]. The worst-case estimates of the ECC using the S-parameters provided by [7,8] were both too conservative, and they could even be larger than one in some cases.…”

Section: Introductionmentioning

confidence: 99%

Worst-Case Estimate of Envelope Correlation Coefficient for Small MIMO Mobile Antennas Below 1 GHz

Zhao¹,

Tak²,

Choi³

2015

Journal of electromagnetic engineering and science

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A worst-case estimate of an envelope correlation coefficient (ECC) is obtained for small multiple-input multiple-output (MIMO) mobile antennas operating below 1 GHz. The worst-case estimate is numerically derived in this paper using spherical and exponential wave functions. The derived result confirms that the worst-case ECC can be easily obtained from the rotation angle between the radiation patterns of two MIMO elements, which are attained directly from the amplitude of 2D electric field patterns without any additional phase and polarization information. As a practical example, MIMO mobile antennas with different antenna element arrangements are compared to verify the validity of the proposed worst-case estimate. Moreover, based on these analyses, we also suggest an effective approach to reduce the ECC of a small MIMO mobile antenna operating below 1 GHz by properly locating the antenna elements to make the radiation patterns perpendicular to each other. This is an Open-Access article distributed under the terms of the Creative Commons Attribution Non-Commercial License (http://creativecommons.org/licenses/ by-nc/3.0) which permits unrestricted non-commercial use, distribution, and reproduction in any medium, provided the original work is properly cited. ⓒ Copyright The Korean Institute of Electromagnetic Engineering and Science. All Rights Reserved. ZHAO et al.: WORST-CASE ESTIMATE OF ENVELOPE CORRELATION COEFFICIENT FOR SMALL MIMO MOBILE ANTENNAS BELOW 1 GHz 45worst-case estimate of the ECC through a direct derivation using the spherical and exponential wave functions. Then, the correctness of this worst-case estimate is verified by comparing MIMO mobile antennas that operate at 0.8 GHz and under different arrangements of the antenna elements. Moreover, by investigating the different factors (rotation angle, translation of phase centers, and occasional pattern variance) related to the ECC, we prove the rotation angle, which is chosen to estimate the worst-case ECC, is also an effective applicable factor to reduce the ECC for a MIMO mobile antenna below 1 GHz. A low ECC can be attained when the rotation angle of a MIMO mobile antenna approaches 90° by locating two antenna elements on the perpendicular edges of the ground plane. II. WORST-CASE ESTIMATE OF ECCIn this paper, we assume the antennas are operating in an isotopic/uniform multi-path condition (XPR = 1 and P θ = P φ = 1/4π) [13,14].Based on the above assumption, the ECC ( e  ) is inversely proportional to the diversity of the radiation patterns and can be expressed in the spherical coordinate Ω = ( θ , ϕ ) using thewhere, and E θ n and E ϕ n are the θ -and ϕ -polarized complex electric field intensities of the antenna element n. Meanwhile, we note the diversity and corresponding ECC are mainly determined by three factors (rotation angle, translation of phase centers, and occasional pattern variance) in MI-MO antennas. Thus, our investigation of the worst-case ECC will start by exploring and comparing these three factors.In addition, we analyz...

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Design of novel compact eight‐element lotus shaped UWB‐MIMO antenna with triple‐notch characteristics on hollow substrate

Addepalli

Manda²,

Vidyavathi

et al. 2023

Int J Communication

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The design of novel compact two-element and eight-element lotus shaped multiple-input-multiple-output (MIMO) antenna system employing pattern diversity with enhanced isolation characteristics is presented. The proposed two-element antenna system is arranged rotationally on a square-hollow substrate resulting in an eight-element MIMO antenna system employing pattern diversity. The developed eight-element MIMO antenna system resonates in the frequency range 3.1 to 14.6 GHz housing the complete UWB band with triple band-notch characteristics at 3.7-4.5 GHz (C-band satellite down link [3.7-4.2 GHz]), 5.1-5.9 GHz (WLAN) and 6.8-8.25 GHz (X-band satellite down link (7.25-7.75 GHz) and up link (7.9-8.4 GHz)) bands. The antenna system gives element-to-element isolation of more than 25 dB in the majority of the operating band with a peak gain of 6.8 dBi and a maximum 90% efficiency. The important MIMO metrics like ECC (envelope correlation coefficient), DG (diversity gain), total active reflection coefficient (TARC), channel capacity losses (CCL) and MEG (mean effective gain) are presented for both twoelement and eight-element to estimate the performance the proposed antennas in multi-antenna environments. The both two-and eight-element designs are fabricated and the measured results of those are well agreed with simulation results.

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Relationship between radiation pattern correlation and scattering matrix of lossless and lossy antennas

Cited by 43 publications

References 3 publications

On the use of wheeler cap for MIMO antennas

On the use of wheeler cap for MIMO antennas

Worst-Case Estimate of Envelope Correlation Coefficient for Small MIMO Mobile Antennas Below 1 GHz

Design of novel compact eight‐element lotus shaped UWB‐MIMO antenna with triple‐notch characteristics on hollow substrate

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