Small Ground Plane Research Articles

A miniaturized multi-wideband Quasi-Yagi MIMO antenna system

A multi-band directional multiple-input–multiple-output (MIMO) antenna system is presented based on a rectangular loop excited Quasi-Yagi configuration. A 64% reduction in size is obtained using a rectangular meandered element as well as a small ground plane. The proposed two-element MIMO antenna system covers the Telemetry L-band and several LTE/WLAN bands. It has a wide measured bandwidth of 689 MHz (1.897–2.586 GHz) in the desired band centered at 2 GHz, and a measured bandwidth of more than 168 MHz across rest of the bands. The MIMO antenna system has a total size of 45 × 120 × 0.76 mm3, with a single element size of 55 × 60 × 0.76 mm3. The non-desired back-lobe radiation which is obtained using a small ground plane, is significantly reduced by using a novel defected ground structure (DGS) as compared with the complex techniques present in literature. The proposed DGS provides a high measured front-to-back ratio of 14 dB at 2 GHz and 11 dB in other bands. A maximum measured realized gain of 5.8 dBi is obtained in the desired band using a single parasitic director element. The proposed MIMO antenna system has a minimum measured radiation efficiency of 70%, isolation of 12 dB, and envelope correlation coefficient of 0.098 within all bands which ensures very good MIMO performance.

Design of 2.4 GHz/5 GHz planar dual-band electrically small slot antenna based on impedance matching circuit

A dual-band electrically small antenna based on impedance matching circuit is proposed. Which is fed by coplanar waveguide (CPW). The antenna includes two twin-spiral type slot-line short stubs and three open-circuited series-stubs with slot-line loaded at the central feed line of the CPW as impedance matching network. The total size of the antenna is 12.45mm×13.05mm×0.8mm , with Kα=0.45 and 0.95 at 2.4 GHz and 5 GHz respectively. By the introduction of the proposed impedance matching network, the syntonic frequency of the antenna is achieved at 2.4 GHz and 5 GHz. And the measured bandwidth of S11<-10dB is about 7.5% and 12% of the two resonant frequencies. The proposed antenna has a very small ground plane (0.9mm×1.8mm). And it is appropriately applied to wireless communication for considerable radiation efficiency.

Compact Laterally Radiating Dielectric Resonator Antenna With Small Ground Plane

A unilateral probe-fed rectangular dielectric resonator antenna (DRA) with a very small ground plane is investigated. The small ground plane simultaneously works as an excitation patch that excites the fundamental TE111 mode of the DRA, which is an equivalent magnetic dipole. By combining this equivalent magnetic dipole and the electric dipole of the probe, a lateral radiation pattern can be obtained. This complementary antenna has the same E- and H-Planes patterns with low back radiation. Moreover, the cardioid-shaped pattern can be easily steered in the horizontal plane by changing the angular position of the patch (ground). To verify the idea, a prototype operating in 3.5-GHz long term evolution band (3.4–3.6 GHz) was fabricated and measured, with reasonable agreement between the measured and simulated results obtained. It is found that the measured 15-dB front-to-back-ratio bandwidth is 10.9%.

Design of a Ceramic Patch Antenna for Artillery Projectile Positioning Applications

본 논문에서는 GPS/GLONASS 신호 수신을 위해 포탄 신관에 탑재되는 소형 원편파 패치 안테나를 제안하였다. 제안된 안테나는 모서리가 절단된 슬롯형 세라믹 패치와 작은 원형 접지판으로 구성된다. 충분한 원편파 대역폭을 얻기 위해 패치 중앙의 2곳에 소형 슬롯을 배치하고 안테나의 요구되는 임피던스 대역폭을 얻기 위해 패치의 상부 왼쪽 모서리를 절단하였다. 신관 내부에 설계된 안테나는 높이 6㎜와 직경 36㎜의 공간을 차지한다. 안테나의 최적 설계 및 주요 설계 변수에 따른 영향은 CST사의 Microwave StudioTM 프로그램으로 분석하였다. 제작된 안테나는 플라스틱 폼으로 포팅되어 있는 신관 레이돔 내부에 실장된다. 제작된 안테나는 2.5~4.2㏈ic 이득, 5.1~11.6㏈ 축비 및 1.57~1.62㎓에서 –10㏈이하의 반사계수 특성을 보였다.

Mobile antenna performance improvement by ground mode tuning using a closed loop

An antenna with a modified ground plane is proposed for modern mobile devices in the wireless communications. The proposed antenna design comprises a planar inverted-F antenna with a feeding capacitor (C F) at the top side of the ground plane, and an additional closed loop with lumped inductors (L1 and L2) at the end of the ground plane. The closed loop is connected to the small ground plane for ground mode tuning so that the ground mode resonant frequency is equal to the operating frequency. In the simulation, the −10 dB bandwidth is 140 MHz (from 2.39 to 2.53 GHz) without the closed loop, and is 320 MHz (from 2.34 to 2.66 GHz) with the proposed closed loop. The measured efficiency is 61% on average from 2.3 to 2.6 GHz for the proposed antenna, and is 36% for the reference antenna. The ground mode resonance can be easily tuned, and the proposed technique is a versatile approach for antenna performance improvement.

Low-profile patch antennas for biomedical and wireless applications

Printed microstrip-fed antennas based on a slotted radiating patch are proposed herein. First, a basic rectangular antenna without any slots was designed, being suitable for wideband applications and showing impedance bandwidth of 2714 MHz for $$S_{11} < -10$$S11<-10 dB. Next, dual-band operation for worldwide interoperability for microwave access (WiMAX, from 3.11 to 3.97 GHz) and wireless local-area network (WLAN, 4.97---5.71 GHz) was obtained by including slots only on the left side of the basic design. Then, using a structure with slots on the right side of the radiating patch, WLAN operation was obtained in the frequency range of 2.865---2.096 GHz. The fourth antenna, with slots on both sides of the patch, was characterized and realized for biomedical applications at 2.45 GHz ($$S_{11} <-10$$S11<-10 dB). The proposed antennas can be realized with small ground plane size and total antenna area of only $$27.5 \times 21\,\hbox {mm}^{2}$$27.5×21mm2. This reduction in total antenna area is achieved by using a truncated patch. All the simulations were carried out using Empire XCcel. The designs were characterized based on their radiation pattern, return loss, voltage standing wave ratio (VSWR), gain, and current distribution. The simulated and measured results show good compatibility.

A Compact Quasi-Isotropic Shorted Patch Antenna

A compact shorted patch antenna with quasi-isotropic radiation pattern is proposed in this paper. The antenna consists of a radiating patch, a small ground plane that has the same dimensions with the top patch, and a metallic sidewall which connects the former two. A coaxial probe is used to feed the antenna and excite its fundamental TEM mode, whose magnetic field generates surface electric current on the shorted sidewall and electric field generates surface magnetic current on the open-ended aperture. Due to the inherent properties of the electric and magnetic fields, the corresponding currents are found not only perpendicular but also quadrature with each other, and, therefore, the patch antenna can provide a quasi-isotropic radiation pattern without involving complex feeding circuit. To verify the theory, a prototype operating at 2.4-GHz WLAN band was designed, fabricated, and measured. Reasonable agreement between the calculated, simulated, and measured results is obtained. It has been shown that the difference between the maximum and minimum radiation power densities is ~2 dB over the entire spherical radiating surface, and the difference can be further reduced to ~0.9 dB by using a lower profile.

Miniaturized Dual-Band Folded Patch Antenna With Independent Band Control Utilizing an Interdigitated Slot Loading

A compact linearly polarized dual-band patch antenna with low cross-polarization and independent band control is presented. Miniaturization was achieved through a combination of shorting, subsequently folding, and by replacing the standard slot loading with a slot that is featured by a meander line. By replacing the standard straight slot with an interdigitated slot loading, the resonance condition was shifted to the lower operating band, facilitating significant antenna miniaturization and resulting in an element size equal to or smaller than $0.1\lambda _{ {0}}$ in all three dimensions. The antenna design procedure is outlined and a prototype for WiFi applications was fabricated and measured for impedance matching, radiation pattern, and broadside gain. A simulated parametric analysis was performed on the interdigitated slot geometry to determine how the antenna performance is controlled. Then, based on the parametric analysis, it was further demonstrated that the two operational bands of the antenna element could be independently controlled by changing only the geometrical dimensions of the interdigitated slot, leaving the base of the antenna entirely unaltered. As a result, the lower operating band could be fixed while the upper operating band could be shifted by up to 10%. Lastly, the effect of utilizing a small ground plane, in an effort to achieve a small antenna footprint, is discussed.

Compact Linearly and Circularly Polarized Unidirectional Dielectric Resonator Antennas

The linearly polarized (LP) and circularly polarized (CP) unidirectional dielectric resonator (DR) antennas (DRAs) with compact ground planes are investigated. Both designs make use of the broadside DR ${\text{HEM}}_{11{{\delta}}}$ mode to obtain the required equivalent magnetic dipoles. The required electric dipoles are provided by the currents on the small ground planes. To demonstrate the idea, both LP and CP unidirectional DRAs operating at 2.4 GHz were designed, fabricated, and tested. Reasonable agreement between the measured and simulated results is observed. It was found that the front-to-back ratio (FTBR) of the LP design is more than 15 dB over the frequency range 2.30–2.55 GHz (10.1% bandwidth). For the CP design, the FTBR is over 15 dB across the frequency range 2.40–2.55 GHz (6.1% bandwidth).

Electrically Small Folded Dipole Antenna for HF and Low-VHF Bands

A novel, highly miniaturized, lightweight antenna operating at the low-VHF band is presented. Earlier studies on an extremely short HF monopole antenna consisting of two in-phase vertical elements face an inevitable issue regarding an unbalanced coaxial cable feed due to the very small ground plane . To resolve this problem, as well as to achieve higher bandwidth, we introduce an electrically small folded dipole version of the same antenna having a fully balanced structure. The overall dimension and total mass of the proposed antenna are $10 \times 10 \times 15 ~\hbox{cm}^3$ . ( $0.013{\lambda _0} \times 0.013{\lambda _0} \times 0.02{\lambda _0}$ at 40 MHz) and 98 g, respectively. The gain and pattern of the fabricated antenna are measured in an elevated range that is in nearly free-space conditions. Measurements are shown to be in good agreement with the design predictions from simulation.

Extended S-Parameter Method for Measuring Reflection and Mutual Coupling of Multi-Antennas

In this paper, a measurement method for the impedance and mutual coupling of multi-antennas that we have proposed is summarized. Impedance and mutual coupling characteristics are obtained after reducing the influence of the coaxial cables by synthesizing the measured S-parameters under the condition that unbalanced currents on the outside of the coaxial cables are canceled at feed points. We apply the proposed method to two closely positioned monopole antennas mounted on a small ground plane and demonstrate the validity and effectiveness of the proposed method by simulation and experiment. The proposed method is significantly better in terms of the accuracy of the mutual coupling data. In the presented case, the errors at the resonant frequency of the antennas are only 0.5dB in amplitude and 1.8° in phase.

Integration and Operation of an Electrically Small Magnetic EZ Antenna With a High-Power Standing Wave Oscillator Source

The efficacy of the three-dimensional, rectangular magnetic EZ antenna for use with mesoband high-power microwave (HPM) sources has been demonstrated previously. It overcomes the typical bulky and massive impedance-matching components found currently in most HPM systems, making it an attractive option when space is very limited. However, its extremely compact nature presents practical challenges when dealing with extremely high-power sources due to the associated local field enhancements near the feed and the near-field resonant parasitic element. This letter presents a fully integrated, high-voltage source and radiating system that has several improvements in the antenna, source, and power system that have not before been demonstrated. The full system includes a ferroelectric generator, standing wave oscillator source, and electrically small antenna ( ${\rm ka} = 0.37$ ) operating at 510 MHz that can be packaged inside a 15-cm-diameter tube. This small diameter results in a quarter-wavelength-diameter ground plane, and the effects of this small ground plane on the radiation characteristics are explored. The development of a pressurized radome allows for operation at 73.6 kV, significantly higher than previous studies.

Analysis of open‐slot antenna radiation pattern using spherical wave expansion

This work explores the impact of the ground plane on a λ/2 open-slot antenna using the spherical wave expansion in the far-field zone. In terms of equivalent radiating sources, the nature of the open-slot antenna radiation pattern is not well assessed. This study shows that for small ground planes, open-slot antenna is a multiple source antenna.

A Wideband Rectangular Dielectric Resonator Antenna with Small Ground Plane

A broadband rectangular dielectric resonator antenna with a small ground plane is presented in this article. A U-shaped slot acts as a feeding structure and an effective radiator simultaneously. A parasitic H-shaped slot is adopted to improve the impedance match. The antenna prototype has been fabricated and tested, and good agreement has been observed between the measured and simulated results. A measured bandwidth for S11 <–10 dB of up to 73.72% and a maximum gain of 6.69 dB have been obtained. The total size of the proposed antenna with the ground plane is only ( is the central operating wavelength).

A dual band-notched ultra-wideband monopole antenna with spiral-slots and folded SIR-DGS as notch band structures

In this paper, an ultra-wideband (UWB) planar monopole antenna with impedance bandwidth from 2.83 to 11.56 GHz and dual band-notched characteristics is presented. The antenna consists of a small rectangular ground plane, a bat-shaped radiating patch, anda 50-Ω microstrip line. The notched bands are realized by introducing two different types of structures. The half-wavelength spiral-slots are etched on the radiating patch to obtain a notched band in 5.15 5.925 GHz for WLAN, HIPERLAN, and DSRC systems. Based on the single band-notched UWB antenna, the second notched band is realized by etching a folded stepped impedance resonator as defected ground structure on the ground plane for WiMAX and C-band communication systems. The notched frequencies can be adjusted by altering the length of resonant cells. Surface current distributions and equivalent circuit are used to illustrate the notched mechanism. The performance of this antenna both by simulation and by experiment indicates that the proposed antenna is suitable and a good candidate for UWB applications.

An ultra low‐profile ultra wideband blade shape monopole antenna

ABSTRACTThis article presents the results of simulation and fabrication of a new ultra wideband ultra low‐profile blade shape monopole antenna. The antenna is a meanderline loaded by lumped elements with an electrically small ground plane. The reflection coefficient and line of sight gain of antenna is simulated and measured. Results indicate that the antenna has a good performance in 30–500 MHz and deep notches in line‐of‐sight gain are eliminated. Design approaches are described and a new structure is developed. Finally, several key points were expressed for a true measurement procedure in cases that the ground plane is electrically very small. © 2015 Wiley Periodicals, Inc. Microwave Opt Technol Lett 57:1695–1699, 2015

IMPACT OF FEEDING LOCATION ON ON-BODY PERFORMANCE OF SMALL ON-GROUND ANTENNAS

In this paper, three commonly used on-ground antenna types (loop, monopole and planar inverted-F antenna) are compared in the scope of wireless body area networks (WBAN) for on-body communications at 2.45 GHz. The bandwidth of the antennas can be enhanced by placing them towards the edge or the corner of the small ground plane (25× 35 mm 2 ) which has, as a consequence, detrimental effects on radiation characteristics that motivates the examination of the impact of feeding location for on-body propagation in detail. The present study quantifies the trade-off between on-body efficiency, the gain in the direction tangential to the surface, applicability to launch creeping waves and bandwidth potential of the different antenna types with various feeding locations. The simulated channel gain |S21| around tissue-equivalent numerical phantoms is compared to an analytical WBAN path loss model.

A Low-Profile and Wideband PILA-Based Antenna for Handset Diversity Applications

A low-profile (5 mm) and wideband planar inverted-L antenna (PILA) is proposed for handset diversity and MIMO applications. It occupies a footprint area of <formula formulatype="inline" xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"><tex Notation="TeX">$702 (= 351 \times 2) ~\hbox{mm}^2$</tex></formula> over the ground plane and consists of two elements arranged utilizing both pattern and spatial diversities to provide a reasonable isolation level. The radiators consist of modified PILAs coupled with a ground plane notch that works as a parasitic radiator; a small ground plane strip is added to shift the lower edge frequency down to 1700 MHz. The single-element and dual-element antennas are analyzed in terms of the reflection coefficient and antenna impedance. Prototypes are made and the measurement results show that this design is good for mobile applications over the frequency range 1700–2850 MHz with a fractional bandwidth of 51%; it covers applications such as DCS 1800, PCS 1900, UMTS, LTE 2300 and LTE 2500, Wi-Fi, and Bluetooth (2400-2448 MHz). Finally, the diversity performance parameters are obtained and evaluated based on both simulation and measurement results. It is demonstrated that the proposed antenna design is a promising candidate for wireless hand-portable applications.

Calibration of Biconical Antennas by Vertically Stacking Method

A new way is proposed, and verified by experiment, to measure the free-space antenna factor (F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</sub> ) of biconical antennas over 30 to 300 MHz by the standard antenna method. The antennas were horizontally polarized above a metal ground plane. The usual method of calibrating electromagnetic compatibility antennas is to place two antennas at a given separation in a horizontal plane. Biconical antennas have a uniform H-plane pattern, making it possible to stack the antennas in a vertical plane. The (F <sub xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">a</sub> ) measured with the new method is in close agreement (difference less than 0.6 dB) to that with the vertically polarized method from the FDIS IEC international standard CISPR 16-1-6. Because the antennas are stacked vertically, a smaller ground plane can be used. Because the antennas are horizontally polarized, the vertically routed cable is orthogonal to the antenna so the interaction of cable and antenna is minimized.

Compact Quasi-Isotropic Dielectric Resonator Antenna With Small Ground Plane

The quasi-isotropic dielectric resonator antenna (DRA) is investigated for the first time. It uses a small ground plane which also serves as an electric dipole. The electric dipole combines with the equivalent magnetic dipole of the DRA to generate quasi-isotropic fields. A choke (balun) is connected to the outer conductor of the coaxial cable to suppress stray radiation. ANSYS HFSS was used to simulate the antenna, and a prototype operating at 2.4-GHz WLAN band was fabricated to verify the simulation. Results show that the difference between the measured maximum and minimum radiation power densities is 5.6 dB over the entire pseudo spherical radiating surface. By using a narrower ground plane and a higher dielectric constant, the gain difference can be reduced to 3.4 dB, approaching the theoretical limit of 3 dB.