To optimize the design of a high-sensitivity receiver, it is valuable to be able to assign noise budget contributions to various parts of the system. The system noise and aperture efficiency can be ...characterized using the antenna Y-factor method, which has been added recently to the IEEE Recommended Practice for Antenna Measurements, Std 149-2021. We extend the antenna Y-factor method by showing that it can be used to measure the noise figure of an active antenna and receiver system. With an additional measurement of the receiver noise, the antenna radiation efficiency can be determined. We demonstrate the extended antenna Y-factor method experimentally at X-band for antennas under test, including a horn with near 100% efficiency, microstrip patch antenna with efficiency near 80%, and a patch antenna array with 40% nominal efficiency.
Dielectric loss occurring in tissues in close proximity to UHF-implanted antennas is an important factor in the performance of medical implant communication systems. Common practice in numerical ...analysis and testing is to utilize radiation efficiency (RE) measures external to the tissue phantom employed. This approach means that RE is also dependent on the phantom used and antenna positioning, making it difficult to understand antenna performance and minimize near-field tissue losses. Therefore, an alternative methodology for determining the intrinsic radiation performance of implanted antennas that focuses on assessing structural and near-field tissue losses is presented. The new method is independent of the tissue phantom employed and can be used for quantitative comparison of designs across different studies. The intrinsic RE of an implant antenna is determined by assessing the power flow within the tissue phantom at a distance of at least λ g /2 from the radiating structure. The simulated results are presented for canonical antennas at 403 and 2400 MHz in homogeneous muscle and fat phantoms. These illustrate the dominance of propagating path losses in high-water content tissues such as muscle, whereas near-field dielectric losses may be more important in low-water tissues such as fat due to the extended reactive near-field.
This paper proposes a simple yet accurate method for estimating the antenna correlation coefficient (ACC) of a high‐order multiple‐input multiple‐output (MIMO) antenna. The conventional method ...employed to obtain the ACC from three‐dimensional radiation patterns is costly and difficult to measure. An alternate method is to use the S‐parameters, which can be easily measured using a network analyzer. However, this method assumes that the antennas are highly efficient, and it is therefore not suitable for lossy MIMO antenna arrays. To overcome this limitation, we define and utilize the non‐coupled radiation efficiency in the S‐parameter‐based ACC formula. The accuracy of the proposed method is verified by the simulation results of a 4‐port highly coupled lossy MIMO array. Further, the proposed method can be applied to N‐port arrays by expanding the calculation matrix.
We provide results of antenna radiation and total radiation efficiency at millimeter-wave frequencies gathered with a new open-ended waveguide-plate method that is compared to a well-known ...two-antenna method. The new method yields improved uncertainty in antenna efficiency measurements. Both methods are based on use of a reverberation chamber. Measurement results are compared to numerical simulations and good agreement (~3% maximum difference) is achieved. Before performing the efficiency measurements, the chamber configuration was assessed with respect to the Rician K-factor, number of uncorrelated paddle orientations, and coherence bandwidth. We calculated the uncertainty using the NIST microwave uncertainty framework capable of performing parallel sensitivity and Monte Carlo analyses. The framework enables us to capture and propagate the uncertainties in the S-parameter measurements to the final efficiency result. The expanded uncertainty that we achieved for these antenna efficiency measurements is 2.60%.
In this communication, an <inline-formula> <tex-math notation="LaTeX">8 \times 8 </tex-math></inline-formula> dual-polarized traveling-wave antenna array is proposed and studied for in-band ...full-duplex applications. The proposed array consists of single-layer dual-polarized patch antennas with a simple feeding network. Despite the strong coupling among antenna elements, good suppression for the self-interference can be achieved by using differential feedings. To validate the study, an on-board prototype is developed, fabricated, and measured. The results show that good impedance matching responses are found, and high isolation of over 50 dB between the dual-polarized outputs is realized from less than 13.0 to 15.7 GHz. Meanwhile, small sidelobes and low cross-polarization levels with low insertion loss are observed, showing well-designed radiation responses.
A polarization-agility antenna using liquid metal (eutectic gallium indium) with high radiation efficiency is proposed in this letter. This design approach offers possibilities to use the minimum ...amount of liquid metal as well as elastomer, so that a higher-radiation-efficiency liquid metal antenna can be realized. The proposed design is based on an aperture-coupled patch antenna composed of both liquid metal alloy and copper tape. The polarization of this antenna is controlled by the position of the pressure-driven liquid metal encased in four triangle cavities constructed by both the elastic dielectric material (i.e., Ecoflex) and polyethylene terephthalate film. A prototype is demonstrated with a center frequency of 2.45 GHz. Three kinds of polarization including left-hand circular polarization, right-hand circular polarization, and linear polarization are successfully demonstrated. A radiation efficiency higher than 90% is observed in the measurement.
In this paper a compact annular ring micro strip patch antenna with modified ground plane is proposed for UWB applications. The dimensions of proposed antenna are 30 × 26 × 1.6 mm3 which was designed ...on FR4 substrate with the thickness of 1.6 mm, εr = 4.4 and loss tangent parameter 0.02. To enhance the impedance bandwidth of the antenna ground plane is modifiedby extruding an inverted L shape stub and defected with multiple I shaped slots. The radiator consists of annular ringpatch, two circular stubs and one rectangular stub is included to the patch to improve the bandwidth. To design and simulate the proposed antenna CST Studio Suite 2018 is used. The proposed antenna is found with UWB frequency range of 3.1–10 GHz (S11 < −13 dB). Multiple frequency bands are observed in UWB frequency range 3.18 GHz, 6.75 GHz and8.67 GHz with the reflection coefficients of −49.6 dB, −50.2 dB and −45.7 dB respectively. VSWR is less than 2 for the total UWB frequency range. Proposed antenna is better option for UWB applications specially First and third frequency bands (3.18 GHz and 8.67 GHz) are suitable for Radio location (G59) services and second frequency band (6.75 GHz) is suitable for satellite and TV broadcasting applications. Performance of the proposed antenna is evaluated in terms of size, radiation efficiency and radiation patterns and it is better compared with existed systems.
This work describes the designof an SRR-loaded pentagon monopole antenna for super wideband (SWB) applications on Rogers RT/Duroid 5880 dielectric material with dielectric constant of 2.2, and a ...dielectric loss tangent of 0.0009. The pentagon patch radiator is fed with a 50 Ω transmission line placed on the dielectric size of 16 mm × 14 mm × 0.787 mm. In this paper, SRR is etched from the radiating element, and partial ground is added to improve the performance characteristics. The proposed antenna has a bandwidth ratio (BR) of 185.38 and an impedance bandwidth (IBW) of 66.38 GHz at a reflection coefficient of −10 dB. It has a fractional bandwidth (FBW) of 197.85% and a bandwidth dimension ratio (BDR) of 19,786 dB, with a peak gain of 6.2 dB. The proposed antenna covers microwave applications, which cover the following spectrums: L: 1–2 GHz, S: 2–4 GHz, C: 4–8 GHz, X: 8–12 GHz, Ku: 12–18 GHz, K: 18–26.5 GHz, Ka: 26.5–40 GHz, and limited millimetre wave frequencies up to 70 GHz.
From the characteristic mode point of view of electrically small antennas, radiation efficiency normally decreases significantly if multiple modes are well excited. Among all these well-excited ...modes, the one with the lowest modal radiation efficiency determines how much actual radiation efficiency is guaranteed. Based on this idea, this letter proposes a method for improving antenna efficiency using shape optimization approach. The optimized shape can give rise to a high efficiency and an implied high gain after being excited using a single port whose location is easily selected by observing characteristic-mode current distributions.
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