Wide Impedance Matching Bandwidth Research Articles

Mitigating mutual coupling effects on circular polarization for improved bandwidth in MIMO systems: A novel approach

An improved mutual coupling compensation in circularly polarized (CP) multi-input multi-output (MIMO) dielectric resonator antenna (DRA) is presented in this paper. Using trimming approach, the mutual coupling (MC) between closely spaced DRA units at 0.3λ has been significantly reduced while axial ratio performance has been maintained. Mutual coupling reduction is obtained by trimming the DRA to ensure low mutual coupling below −20dB. The exclusive features of the proposed MIMO DRA include wide impedance matching bandwidth (BW), triple band circular polarization, and suppressed MC between the radiating elements. The impedance bandwidth matches perfectly with a triple band's 3 dB axial ratio (AR). It is designed with characteristic mode analysis with good agreement of the measurement that has been obtained. Using the probe feed method, the DRA and patch strip are coupled together to allow bandwidth widening of the pro-posed DRA. An impedance bandwidth of 34% at a lower frequency to around 2% at a higher frequency was achieved in all resonance frequencies. Thus, we refer to our newly designed DRA as a proposed method for effectively reducing the mutual coupling between DRAs. Additionally, the 3 dB AR bandwidth matched at 3.3 GHz, 4.6 GHz, and 6.3 GHz with a percentage of 11.66%, 3.04%, and 2.22% obtained at the three different frequencies. Note that the proposed DRA exhibits low mutual coupling (below −20 dB) at the targeted frequencies, which is suitable for better signal reception for MIMO applications. By computing, the metrics envelop correlation coefficient, diversity gain, channel capacity loss, and total active reflection coefficient, the MIMO performance of the proposed antenna is verified. The experiments show a close result between simulated and computed validation of the proposed DRA.

Triple-Band Circularly Polarized Dielectric Resonator Antenna (DRA) for Wireless Applications

This paper proposes a new dielectric resonator antenna (DRA) design that can generate circularly polarized (CP) triple-band signals. A triple-band CP DRA antenna fed by a probe feed system is achieved with metal strips structure on side of DRA structure. The design start with conventional rectangular DRA with F shaped metal strips on DRA structure alongside the feed. Then, the F metal strip is enhanced by extending the length of the metal strip to obtain wider impedance bandwidth. Further improvement on the antenna performance is observed by improvised the conventional DRA structure. The method of removing part of DRA bottom resulted to higher antenna gain with triple band CP. The primary features of the proposed DRA include wide impedance matching bandwidth (BW) and broadband circular polarization (CP). The primary features of the proposed DRA include wide impedance matching bandwidth (BW) and broadband circular polarization (CP). The CP BW values recorded by the proposed antenna were ∼ 11.27% (3.3–3.65 GHz), 12.18% (4.17–4.69 GHz), and 1.74% (6.44–6.55 GHz) for impedance-matching BW values of 35.4% (3.3–4.69 GHz), 1.74% (5.36–5.44 GHz), and 1.85% (6.41–6.55 GHz) with peak gains of 6.8 dBic, 7.6 dBic, and 8.5 dBic, respectively, in the lower, central, and upper bands. The prototype of the proposed antenna geometry was fabricated and measured. A good agreement was noted between the simulated and the measured results.

A Single-Feed Wideband Circularly Polarized Dielectric Resonator Antenna Using Hybrid Technique With a Thin Metasurface

A compact metasurface-based circularly polarized (CP) dielectric resonator antenna (DRA) is proposed with wideband characteristics. The antenna forms a very simple structure, composed of a rectangular DR, a single coaxial probe and a plus-shaped unit cells based metasurface. The metasurface is realized on a grounded FR-4 substrate. Next, a rectangular DR is loaded centrally over the metasurface. The DR is fed with a perturbed probe feed at an appropriate angle of (θ=29°), along the diagonal line. Thus, a novel hybrid technique involving the angle of feed location from the center of DR, and the N × N unit cells based metasurface is utilized for generating a wideband CP radiation. The resonance from the rectangular DR and surface waves along the 7 × 7 plus-shaped unit cells based metasurface is exploited to achieve a 3-dB axial ratio (AR) and wide impedance matching bandwidth. The fabricated antenna prototype used for the validation of predicted results confirms the successful implementation of the proposed technique. Measured results demonstrate a wide impedance bandwidth of 32% (3.6 GHz - 7.0 GHz) and an overlapping 3-dB AR bandwidth of 20.4% (4.2 GHz - 5.2 GHz). Moreover, the antenna adopts a left-hand circular polarization (LHCP) with 6-7 dBic measured gain within the operational frequency range. Overall, the proposed antenna offers low profile, simplicity, ease of design, and high performance.

Broadband coplanar waveguide‐fed stub loaded pot shape E‐textile antenna equipped with perfect electric conductor

In this paper, a coplanar waveguide (CPW) fed pot-shaped electronic textile (E-textile) antenna aided by rectangular ring ground plane has been proposed. The textile patch in pot form is designed by cutting triangular slots on the non-radiating edges of the rectangular patch, which yields a broadband of 6.45 GHz. The measured antenna impedance bandwidth is from 2.15 to 8.6 GHz with a peak gain of 10.7 dB on fabricated human tissue muscle equivalent phantom model. The proposed antenna exhibits a broadside radiation pattern from 2.15 GHz to less than 6 GHz and conical radiation pattern from 6 GHz to 8.6 GHz covering wide impedance matching bandwidth (S11 ≤ −10 dB) of 120% for dual-mode off and on-body communication. In CPW fed technique, the back radiation from the antenna to on body is reduced by using a perfect electric conductor. For wearable applications, considering human safety concern the specific absorption rate levels are maintained, that is less than 1.6 W/kg limit over the operating bandwidth according to IEEE C95.1-1999 standard averaged over 1 g of tissue model.

Wideband textile multiple‐input‐multiple‐output antenna for industrial, scientific and medical (ISM) /wearable applications

A compact, wideband, two-element textile multiple-input-multiple-output (MIMO) antenna is presented for industrial, scientific and medical (ISM)/wearable applications. The proposed structure is composed of the Felt material substrate, and the ground plane and radiating patch are formed using ShielditTM Super conductive material. The designed MIMO antenna offers a wide impedance matching bandwidth (S11 ≤ −10 dB) of 2.00−6.23 GHz, a very low mutual coupling of (S21,max) −29.26 dB, low envelope correlation coefficient <0.01, high diversity gain ∼9.95 dB, and realized gain of more than 2.88 dBi, over the entire band. The prototype of the proposed antenna geometry is fabricated, and it has a size of 76 × 37 mm2. The proposed antenna could be a good candidate for wearable electronic devices due to its compact size, all textile layers, easy integration, robustness, and reasonable on-body performance.

Circularly polarized rectangular dielectric resonator antenna excited by an off-set conformal metal strip

&lt;p class="Abstract"&gt;A rectangular dielectric resonator antenna (DRA) has been excited by an off-set single conformal metal strip. By using such excitation technique two degenerate resonant modes, TExδ11 and TEy1δ1 of the rectangular DRA have been excited to achieve circular polarization (CP). A CP bandwidth of ~ 5.2% in conjunction with a wide impedance matching bandwidth of ~ 54% has been provided by the proposed DRA configuration. The antenna design has been simulated using computer simulation technology (CST). Antenna prototype has been built to verify the impedance matching bandwidth. Far field parameters have been optimized and verified using two simulation techniques in CST i.e. finite integration technique (FIT) and finite element method (FEM). A good agreement between the simulated and measured result has been observed for S11. Similarly a very good resemblance between the far field results from FIT and FEM have been demonstrated.&lt;/p&gt;

Research on a wide-beam-layered printed antenna for aerocraft telemetry system

ABSTRACTA wide-beam linear polarization antenna with circular patch, ring, microstrip line, and electromagnetically coupled patch is presented in this paper. This antenna was used in missile telemetry system. Circular patch is fed by a coaxial probe directly, and the regular patch is excited by the coupling energy. In order to broaden the antenna beamwidth, the ring and regular patch were added to change the distribution of electromagnetic field. Four microstrip lines were used to obtain a wide impedance-matching bandwidth. This antenna is simulated and optimized by using the full wave electromagnetic simulation technique. It can achieve an impedance bandwidth (S11<-10 dB) of 2.36–2.38 GHz. The simulated results showed a linear polarization radiation with a wide half-power beamwidth (>71.9°) and a high radiation gain (>6.2 dB) within the operational bandwidth. The proposed antenna is fabricated and measured. Measured results show that the proposed antenna achieves the expected radiation performance and validates the effectiveness of the dual polarized antenna design. The wide-beam antenna studied in this paper is suitable for missile telemetry system. The research results have laid a technical foundation for its practical engineering application.

Mutual Coupling Reduction Using Hybrid Technique in Wideband Circularly Polarized MIMO Antenna for WiMAX Applications

In this paper, a novel wideband circularly polarized multiple-input multiple-output (MIMO) dielectric resonator antenna (DRA) has been proposed for worldwide interoperability for microwave access (WiMAX) applications. The mutual coupling (MC) between closely placed DRA units at 0.5λ has been significantly reduced by using a new hybrid technique. The exclusive features of the proposed MIMO antenna include wide impedance matching bandwidth (BW), broadband circular polarization (CP), and suppressed MC between the radiating elements. The first step of hybrid technique is the employment of parasitic patch at an optimized distance beside the conformal metal strip of the two identical rectangular DRAs in order to generate CP wave along with a wide impedance matching BW over the same frequency range. In the final step, the MC is suppressed significantly along with the broadband CP by placing the DRAs diagonally at an optimized position. The proposed MIMO antenna is the hybrid of the parasitic patch and the diagonal position of radiating elements. The CP BW offered by the proposed antenna is ~20.82% (3.58-4.40 GHz) in conjunction with an impedance-matching BW of ~38.51% (3.50-4.95 GHz). Moreover, MC less than -28 dB is achieved over the entire band and -26 dB at 3.89 GHz (minimum of the AR) through the hybrid technique. The prototype of the proposed antenna geometry is fabricated and measured. A good agreement has been attained between the simulated and measured results.

Bandwidth Enhancement and Generation of CP by Using Parasitic Patch on Rectangular DRA for Wireless Applications

A wideband circularly polarized rectangular dielectric resonator antenna (DRA) fed by single feeding mechanism has been studied theoretically and experimentally. The study has been carried out to find out the effect on different antenna parameters when a parasitic strip is attached to the wall beside the conformal metallic feed. The DRA is excited by an E-shaped metal strip. The novel feed produces a narrow impedance matching |S 11 | <; -10 dB bandwidth of 7.94%. Further enhancement is carried out by introducing the parasitic patch at an optimal location on rectangular DRA, such configuration provided a measured circular polarization (CP) waves over a broad bandwidth of 22.01% (3.59 - 4.40 GHz) in conjunction with a wide impedance matching bandwidth of -23% (3.6 - 4.45 GHz). These results represent that; parasitic patch not only generate CP but also an increase by a factor of - 3 times in return loss as compared to those achieved by E-shape feed only. Simulation is done through computer simulation technology (CST-2017). The prototype of the proposed antenna geometry is fabricated and measured. Performance parameters demonstrate that the proposed antenna is well suitable for WiMAX applications. The simulated results agree reasonably with measurements.

LTCC SIW-Vertical-Fed-Dipole Array Fed by a Microstrip Network With Tapered Microstrip-to-SIW Transitions for Wideband Millimeter-Wave Applications

A wideband vertical off-center-fed dipole antenna using low-temperature cofired ceramic technology working at Ka-band is presented first. The dipole is fed by a short-ended substrate integrated waveguide (SIW), and a rectangular transverse slot is built on the upper broad wall of the SIW for better impedance matching. Then, a 2 \times $ 2 array with a dimension of 17 × 25 × 0.94 mm $^3$ , fed by a microstrip network with tapered microstrip-to-SIW transitions, was fabricated and measured. Measured results show that the proposed array has a wide impedance matching bandwidth from 32.9 to 40 GHz or 19.5% for $\mid$ $S$ $_{11}$ $\mid$ $\leq$ $-$ 10 dB. The measured gain of the array is about 10 dBi with slight fluctuations over the frequency range of 29–39 GHz.

A Wideband Aperture-Coupled Microstrip Patch Antenna Employing Spaced Dielectric Cover for Enhanced Gain Performance

A dielectric cover is used to enhance the gain of an aperture-coupled microstrip patch antenna. The cover is spaced off of the patch antenna by air and, as expected, is found to significantly increase antenna broadside directivity in some configurations. A parametric study on the effects of spacing height, cover size, and thickness of the cover are presented. This study uses a finite element method (FEM) based, commercial analysis tool to perform these parametric searches, and so accounts for finite size ground planes and dielectrics. The previous research work reported in literature considered infinite-area ground planes and dielectrics. The wide impedance matching bandwidth of the aperture-coupled microstrip patch also allows observation of the narrow-bandwidth effects of the added dielectric cover. Finally, a proposed design methodology is outlined, and a prototype of the antenna was fabricated and experimentally verified with a peak gain of 13.9 dBi. The measured results agree reasonably well with the simulated ones.

Ultrawideband Dielectric Resonator Antenna With Broadside Patterns Mounted on a Vertical Ground Plane Edge

A novel portable dielectric resonator antenna (DRA) design with broadside radiation is presented for ultrawideband wireless applications and narrow pulse sensor for breast cancer detections. The antenna provides broadside radiation. By using a solid rectangular dielectric resonator mounted on a vertical ground plane edge, the total antenna volume is considered to be less than that with a perpendicular ground plane. A wide impedance matching bandwidth is achieved. In addition, a modified version of the rectangular dielectric resonator antenna, which has two dielectric pieces removed to have an A-shaped resonator, provides wider impedance matching bandwidth of around 93% with much better broadside radiation characteristics and lighter weight is also considered. Comparison between the two antennas is presented with parametric study. The modified antenna is built and tested and very good agreement between computed and measured results is obtained.

Application of segmentation analysis to a matched U‐slot patch antenna

AbstractA wide impedance matching bandwidth or multi‐band response can be obtained using a single layer U‐slot rectangular antenna with a probe feed. However, the determination of the input impedance of this antenna has not been reported. In this letter using segmentation analysis a new explicit matrix input impedance formula has been derived. The U‐slot rectangular antenna is partitioned into rectangular segments and the system of coplanar matrix circuit equations is reduced by cojoining pairs of equations. The reduced system is then solved to obtain a new explicit matrix input impedance formula. This technique has the potential to be applied to other multi‐segmented antenna geometries. Two antennas operating at 2.45 GHz were fabricated, one with a substrate of thickness 1.575 mm and the other with a substrate of thickness of 3.175 mm. For both antennas there is an excellent agreement between the predicted, simulated, and measured results for the input impedance. © 2008 Wiley Periodicals, Inc. Microwave Opt Technol Lett 50: 2608–2611, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.23743