Modified Ground Structure Research Articles

A Compact On/Off-Body Dual Band Antenna with Modified Ground for Healthcare Applications

ABSTRACT In this paper, a compact dual-band radiator with a modified ground structure is presented for on/off body communication. The antenna is capable of resonating in the ISM-I (2.4 GHz) and WLAN (5.15–5.85 GHz) bands. The proposed antenna consists of a novel compact ring loaded with a C-shaped radiator for dual-band operation. To improve impedance matching and shifting of the lower band at the ISM-I band, a modified ground structure is used. This suggested antenna has a small footprint of 0.24λ0×0.22λ0×0.016λ0, wherever λ0 is the free space wavelength at the lower operational frequency. The proposed antenna is parametrically studied, as well as the analysis of electric field and SAR at different positions on the arm are also carried out to check its utility for medical applications. The proposed antenna's specific absorption rate (SAR) meets IEEE standards and the prototype's measured findings validate the simulation's results.

Characterization of dual-band circularly polarized mushroom-shaped monopole antenna with modified ground plane

Abstract In this manuscript, an antenna design configured for dual-band circularly polarized (DBCP) characteristics is presented. The proposed design is quite compact (0.63 λ g × 0.63 λ g × 0.04 λ g) and comprises a mushroom-shaped monopole with a modified ground structure (MGS). In the proposed antenna structure, dual-band CP behavior is generated through a tunable side stub joined orthogonally with the feed patch and reshaping the wide square slot. The impedance bandwidth is measured as 2900 MHz ranging from 1.32 to 4.22 GHz in the lower frequency band (Band 1); however, 980 MHz from 4.78 to 5.76 GHz in the higher frequency band (Band 2). The 3-dB AR bandwidth is measured as 370 MHz (from 3.54 to 3.91 GHz)in the lower frequency band; whereas, it is measured as 650 MHz (from 5.07 to 5.72 GHz) in the higher frequency band. The measured gains spread from 2.5 to 8.3 dBi with a maximum gain of 8.3 dBi in the lower frequency band, whereas 4.8 to 7.05 dBi with a 7.05 dBi maximum gain in the higher frequency band, respectively. The cross-polar rejection is observed greater than 14 dB. Besides, 3-dB half-power beamwidths are seen as 86° & 84°, and 87° & 86° in the x-z and y-z planes for the lower and higher frequency bands, respectively.

Multi-band different polarized monopole antenna with modified ground for WLAN & Wi-MAX applications

ABSTRACT This paper presents the design and analysis of a multi-band, dual-polarised monopole antenna consisting of a simple equilateral triangular monopole patch configured with a modified ground structure (MGS). In the presented antenna design, quad-band dual-polarised operation has been obtained by creating the three unequal rectangular slots on the ground structure. The proposed monopole antenna produces four individual frequency bandwidths with the dual sense of polarisation, namely linear polarisation (LP) and circular polarisation (CP). The antenna produces quad-band behaviour with linear wave polarisation in Band1, whereas right-hand circular polarisation (RHCP) in rest frequency bands viz. Band2, Band3, and Band4. The measured impedance bandwidths spread from 2.50 to 4.42 GHz in band2; 5.22 to 6.28 GHz in band3; and 8.40 to 10.30 GHz in band4; whereas the impedance bandwidth extends from 1.35 to 2.14 GHz in linearly polarised band 1. The measured axial ratio bandwidth (ARBW) extends from 2.82 to 3.20 GHz in band2; 5.17 to 5.94 GHz in band3; and 9.30 to 9.70 GHz in band4, respectively. The constant gain profile has been observed in all frequency bands. The proposed antenna can be applied for WLAN/ WiMAX and Wi-Fi applications.

Mutual Coupling Reduction between Finite Spaced Planar Antenna Elements Using Modified Ground Structure

In this paper, a modified ground structure capable of reducing mutual coupling to provide isolation between adjacent antenna elements is presented. The proposed modified ground structure is a combination of a strategically located ground slot, asymmetric partial ground and a substrate-integrated pin wall. The use of the modified ground structure causes a more than 28 dB (measured value) mutual coupling reduction. The modified ground structure has been optimized and validated with a finite spaced planar 2 × 1 antenna array operating at 4.16 GHz, intended for unmanned aerial vehicle radar altimeter applications. The patch antennas built with the MGS exhibit high gain (greater than 6 dBi throughout the operational band), along with inter-element coupling as low as −65 dB. Mutual coupling reduction at lower contours is beneficial for altimeter applications.

Isolation improvement of compact LTE MIMO terminal using combination of neutralisation line and modified ground structure

A multi-wideband MIMO antenna is presented for LTE MIMO terminals. The proposed antenna covers LTE700, GSM1800, GSM1900, UMTS, LTE2500, and Wi-Fi frequency bands. The multi-antenna elements are placed at the top two corners of printed circuit board (PCB) in the mirror image position. Each antenna element consists of a driven element and a shorted radiating element. To make the compact antenna structure, radiating element is meandered, folded, and shorted to the ground through copper wire. The size of each radiator is 15 × 25 × 4 mm3. Further, a combination of neutralisation line and modified ground structure is designed and deployed between radiating elements to reduce the mutual coupling between them. According to the measurement results of the fabricated antenna prototype, the isolation between two antenna ports is better than -12 dB over the operating frequency band. The simulated and measured results are found in close agreement. Moreover, to investigate the performance of the proposed antenna on the real application platform, mobile environment and user proximity analyses are carried out. Besides, total radiated power (TRP), channel capacity loss (CCL) and specifi c absorption rate (SAR) to peak location spacing ratio (SPLSR) are calculated and found well below the limit of Federal Communication Commission (FCC) standard.

A compact flower slotted dual band notched ultrawideband antenna integrated with Ku band for ultrawideband, medical, direct broadcast service, and fixed satellite service applications

AbstractA compact flower slotted antenna (FSA) for dual band eliminated ultrawideband (UWB) integrated with Ku band applications is proposed. The basic FSA with modified ground structure is utilized for obtaining fractional bandwidth of 137% (3.45‐18.45 GHz). The dual band eliminated frequencies are achieved by a via hole to eliminate 5.39 to 5.90 GHz (upper WLAN band) frequencies and by utilizing symmetrical inverted L‐shaped parasitic elements to notch 7.30 to 7.75 GHz (downlink of X‐ band satellite communication link) frequencies. The FSA is having a compact size of 16 × 22 mm2 printed on low cost FR‐ 4 substrate with two band notched characteristics, nearly omnidirectional radiation characteristics and stable gain over UWB frequency range makes it suitable for portable UWB systems.

Asymmetrical mirror imaged monopole antenna with modified ground structure for DBDP radiations

ABSTRACTIn this article, asymmetrical mirror-imaged monopole antenna comprises a rectangular patch with tuneable stub and supported with modified ground structure (MGS) is investigated. The proposed antenna is characterised for dual band dual polarised (DBDP) radiations and can operate at 2.45 GHz for Wi-Fi and WLAN systems (2.4–2.485 GHz) and 5.45 GHz for WLAN band (WLAN band: 5.2–5.8 GHz) with the corresponding polarisations. A rectangular patch integrated with tuneable stub and a pair of asymmetrical inverted L-shaped slots positioned at ground plane is responsible for circularly polarised higher band; while a parasitic patch is created due to slotting of a mirror-imaged stub from the extended ground plane which is accountable for lower frequency band. The fabricated prototype shows that the measured Impedance bandwidths (VSWR < 2) are 350 and 1770 MHz for lower and higher frequency bands, respectively. The measured axial ratio bandwidth (AR < 3 dB) is yielded as 1450 MHz centred at 5.44 GHz for higher frequency band. The peak gains are measured as 4.3 and 4.15 dB for lower and higher frequency band, respectively. For the prototype antenna, substantial 3-dB beamwidth is found along with good cross polarisation suppression.

A novel ITI-shaped isolation structure placed between two-port CPW-fed dual-band MIMO antenna for high isolation

In this paper, a novel structure of CPW-Fed MIMO antenna is presented for dual-band applications covering 2.4/5.8 GHz ISM band, 2300 MHz LTE-4G band, HiperLAN (5–6 GHz) and IEEE C-bands. A Rectangle-Split-Ring-Resonator (RSRR) slot has been embedded in the patch antenna to create a band-notch centered around 3.74 GHz in order to isolate the high traffic of 3.5 GHz WiMAX band and convert a wideband antenna into a dual-band antenna which is mainly focused on the WLAN bands. A modified ground structure is implemented to control and achieve a higher impedance bandwidth (IBW) up to 64% in the upper band, ranging from 3.90 to 7.55 GHz while the lower band, ranges from 2.24 to 2.90 GHz with an IBW of 26%. A novel ITI-shaped isolation structure is designed and placed between the patch antennas, which are separated by a center-to-center distance of 0.35λ0, helping in achieving a minimum measured isolation of 24 dB across the dual-band. The design has been fabricated on an FR-4 substrate of dimension 72 × 56 × 0.8 mm3 with a minimum measured gain of 2.5 dBi across the operating bands.

An Optimal Design of Fractal Antenna with Modified Ground Structure for Wideband Applications

This paper premeditates an optimal design of fractal antenna with modified ground structure for wideband applications. The proposed antenna has been designed by taking numerous iterations started from 0th to 3rd. To attain the wideband characteristics, the partial ground plane has been introduced in the 3rd iteration, and the length of the ground plane has been varied to enhance the bandwidth. The maximum value of bandwidth has been adorned in the final iteration as 1.88 and 0.20 GHz. Further, this bandwidth has been improved and embellished as 2.48 GHz within the frequency range of 3–6 GHz by employing horizontal and vertical extensions in the partial ground plane. Antenna is simulated by using HFSS and performance parameters of antenna like return loss (S11 ≤ − 10 dB), gain and radiation efficiency are in the acceptable limits. The maximum value of gain is reported as 5.1 dB and radiation pattern is also omnidirectional. The proposed antenna is useful for the wireless applications as WiMAX (3.4–3.69 GHz) and WLAN (5.15–5.35 and 5.72–5.82 GHz) Simulated and experimental results are also juxtaposed and found in good agreement with each other.

Miniaturization of a CPW-fed Dual-Band Antenna for GSM 1800/1900 and WLAN 5 GHz Applications

This paper presents a unique and miniaturized dual-band coplanar waveguide (CPW-fed) antenna for modern wireless communication. A new technique of using a modified ground structure (MGS) and frequency shifting strips (FSS) has been employed in the design to achieve dual-frequency operation. The proposed antenna generates two separate impedance bandwidths and covers the minimum required frequency bands of GSM 1800, GSM 1900, and Wi-Fi/WLAN 5 GHz. The proposed antenna is relatively small (<TEX>$17{\times}20mm^2$</TEX>) and operates over frequency ranges 1.51~2.06 and 4.43~6.70 GHz. The designed antenna was simulated using Ansoft HFSS, a FEM based simulator, and antenna characteristics, such as reflection coefficient, gain, radiation efficiency, radiation pattern, impedance bandwidth, VSWR, surface current, and electric field distributions, are reported in this paper. The effect of the antenna's key structural parameters on its performance is also analyzed.

Effects of Modified Ground Structure on a CPW-fed Patch Antenna

Effects of Modified Ground Structure on a CPW-fed Patch Antenna

Design and Analysis of a New Dual-Band Microstrip Fractal Antenna

Abstract—This paper presents a novel design of a microstrip fractal antenna based on the use of Sierpinski triangle shape, it’s designed and simulated by using FR4 substrate in the operating frequency bands (GPS, WiMAX), the design is a fractal antenna with a modified ground structure. The proposed antenna is simulated and validated by using CST Microwave Studio Software, the simulated results presents good performances in term of radiation pattern and matching input impedance.

Design of a compact ultra‐wide‐band monopole antenna with band rejection characteristics

This study presents a design of two compact monopole antennas with band-notched characteristics for ultra-wide-band application. The compact antennas are etched on an FR4 substrate with the size of 14 × 16 × 1 mm3, consists of a tree-shaped radiation patch with modified ground structure, providing a wide usable fractional bandwidth of more than 170% (2.8–19.2 GHz). To reject certain-frequency bands, two completely different approaches are proposed. First a shorted T-shaped quarter-wavelength resonator is used to omit undesired frequency band of 5.1–5.9 GHz. In the second approach, two L-shaped slots are inserted in the patch to act as a filter structure for worldwide interoperability for microwave access (3.4–3.6 GHz) and wireless local area network (5–5.6 GHz) applications. The band-notched can be controlled by adjusting the length of the rectangle slots. The effects of dimensional parameters on the antenna performance have been investigated through a parametric study. Furthermore, current density distribution on the antenna is also computed to gain a better insight of its behaviour. The antennas are investigated numerically and experimentally for their impedance matching properties, frequency notched characteristics and radiation performances.

Compact ultra‐wideband antenna with band‐notched based on defected ground structure

A simple and very compact planar monopole ultra-wideband antenna with a 3.5 GHz band rejection is proposed in this Letter. The compact antenna is etched on an FR4 substrate with the size of 14 × 16 × 1 mm3, consists of a tree-shaped radiation patch with modified ground structure. To reject certain frequency band, a pair of parallel strip patch, acting as a parasitic element is used. Prototype of the proposed antenna was constructed and measured. The measured impedance bandwidth of the realised antenna with optimal parameters is from 2.6 to 12 GHz (128%) for voltage standing wave ratio <2 with an unwanted band notched from 3.3 to 4 GHz. Moreover, the antenna has good omnidirectional radiation patterns in the H-plane.

이중층 패치와 부분 제거된 접지면을 이용한 광대역 평판형 역 F 안테나의 설계

In this paper, we proposed a wideband design of planar inverted-F antenna(PIFA) using two-layer, patches and modified ground structure. The antenna consists of two layer patches with common feed and modified ground plane to control resonance frequency and antenna input impedance. The measured bandwidth is 1,492 MHz(BW: 67.7 %, 1,457 MHz) for VSWR6,140 MHz) for VSWR