The increasing use of antennas in the biomedical domain is transforming healthcare by facilitating advanced communication and monitoring capabilities in medical devices. Specifically, the Planar Inverted-F Antenna (PIFA) has solidified its position in diverse biomedical applications due to its compact and low-profile characteristics. This paper presents the design of a dual-band PIFA antenna. The proposed design is compact and simple in design with a size of 50×30×3 mm3. The antenna resonates at the frequencies of 3 GHz and 5.3 GHz. The resonant frequencies have been tuned by employing reactive loadings with the use of shorting pin and slots. Also, the ON body characterization of the antenna has been performed on human skin phantom model with pre-defined dielectric properties.

A flexible wearable antenna with wideband characteristics and having a conical radiation pattern which is suitable for ON body application is presented.To realize a compact antenna size, characteristic modal (CM) analysis is performed initially, and the ground plane of the antenna is utilized to generate one of the resonant modes.The quasi-current loop in the feed layer patch is used to generate another resonant mode.Combination of these two modes has resulted in the wideband performance of the antenna from 4.72 to 6.08 GHz.A planar wideband artificial magnetic conductor (AMC) is used beneath the antenna.This AMC surface compensates the undesired coupling taking place due to the ground radiator thereby reducing the specific absorption rate (SAR) to 76.4% and enhancing the gain of the antenna.The performance of the antenna in terms of return loss, gain, efficiency, SAR and bending sensitivity is studied.

In this paper a switchable THz antenna is designed using the varying electrical characteristics of graphene and vanadium-di-oxide material at THz frequency. A microstrip line fed monopole antenna is printed over a silicon-di-oxide substrate with a partial ground plane at the bottom. The radiating patch is made of graphene material whereas the ground plane is assigned by VO 2 material. By varying the chemical potential of graphene and conductivity of VO 2 , the impedance and electrical behaviour of these materials are changed. This idea has been applied to switch the printed monopole antenna to the printed dipole antenna and vice-versa without modifying the antenna geometry. To avoid the design repetition at THz frequency this method of tuning the antenna found preferable than by any mechanical tuning. Moreover, the monopole antenna exhibits excellent wideband characteristics and can be employed for high data rate communication.

In this article, a geometrically simple, microstrip line‐fed planar monopole structure with slanting edge ground plane is designed to realize the dual‐band dual‐polarized operation. The proposed antenna consists of a rotated U‐shaped patch and an electromagnetically coupled L‐shaped parasitic radiating element. Owing to the combination of microstrip line‐fed radiating patch and a slanting‐edge rectangular ground plane on the opposite side of the substrate, the proposed dual‐band antenna can generate broad axial ratio bandwidth (ARBW) in the upper frequency band. The overall dimension of the prototype is only 32 × 32 × 1.6 mm3. The measured results validate that the proposed antenna has two operational frequency bands, 29.84% (1.54‐2.08 GHz) for linearly polarized radiation and 71.85% (3.96‐8.4 GHz) for circularly polarized radiation. Measured result shows that 3‐dB ARBW of the proposed antenna is 73.54% (3.80‐8.22 GHz) in the higher frequency band. It shows that the higher frequency band exhibits a left‐hand circularly polarized radiation in the boresight direction.

A dual band dual mode triangular textile patch antenna is proposed for body-centric communication. The antenna has a broadside radiation pattern at 2.5GHz for supporting OFF body link whereas a conical-like radiation pattern at 5.8GHz for ON body link. Tuning of both broadside and conical radiating modes to the specific frequencies is achieved by loading three shorting pins and two symmetrical open-ended slots. This approach has resulted in the realization of the dual band-dual mode antenna using a single radiator with a simple structure. An all textile design further enhances the practicability of the antenna for wearable applications respectively.

This paper presents a CPW-fed dual-band dual-sense circularly polarized square slot antenna (CPSSA). The antenna consists of a rectangular radiator with two unequal rectangular strips, connected by a CPW feed line. An inverted L-shaped grounded stub is placed in the right side of the slotted ground plane with the orthogonal direction of the feed line to create CP modes. The proposed antenna obtained two CP bandwidths of 3.30-3.78 GHz and 5.4-5.86 GHz with axial ratio (AR) value less than 3 dB, and both the CP bands are overlapped by impedance bandwidth (IBW) of the antenna, ranging from 2.72 to 7.34 GHz. Total size of the proposed antenna is 50 x 50 x 1.58 mm(3). The antenna is fabricated on an FR4-epoxy substrate and measured. Simulation results are verified by measurement for the given antenna. The designed antenna is well used for WiMAX (3.5 GHz and 5.5 GHz) band with CP characteristics. Design procedures of the antenna are discussed in details for further understanding of the antenna design. Parametric study has been done for describing the mechanism of the dual-band CP with the analysis of electric current distribution of the antenna. Meanwhile, wide axial ratio bandwidth has been obtained in both the bands using this structure compared to other published structures.

A simple and compact triple-band dual-sense circularly polarised (CP) microstrip line fed planar monopole antenna is presented here with ultra-wide impedance bandwidth. The proposed antenna comprised a slit-loaded semi-circular radiating patch and a stub-loaded modified ground plane. By properly embedding a slit into the patch and a stub into the modified ground plane, the proposed monopole structure radiates triple band CP in broadside direction. The overall size of the proposed antenna is 40 x 40 x 1.6 mm(3). The proposed antenna is capable of generating right hand CP wave in the lower and upper CP band, while left hand CP wave is generated by the middle CP band. The measured - 10 dB impedance bandwidth is 122% (2.74-11.32 GHz) and 3-dB axial ratio bandwidths for the triple bands are 41.55% (4.08-6.22 GHz), 17.03% (7.52-8.92 GHz) and 14.68% (9.34-10.82 GHz), respectively. The measured peak gains within three CP bands are 4.24, 4.02 and 3.78 dBic, respectively.

The design of a broadband circularly polarized compact monopole antenna is proposed in this letter. By protruding a G-shaped parasitic strip into a C-shaped monopole antenna structure, two orthogonal modes are created with equal amplitude and 90 phase difference for circular polarization. A 3 dB axial-ratio bandwidth (ARBW) of the antenna is greatly extended by using a modified ground plane. With the help of these features, a compact broadband circularly polarized antenna is designed and fabricated. Experimental results show that the proposed antenna realizes -10 dB impedance bandwidth of 62.94% (3.92-7.52 GHz) and ARBW of 53.92% (4.28-7.44 GHz). Overall size of the proposed monopole antenna is 0.57 lambda(0) x 0.614 lambda(0) x 0.03 lambda(0), where lambda(0) is the free-space wavelength at the center frequency of the operating bandwidth. The proposed antenna is desirable for MAN (5.15-5.85 GHz) applications and various wireless communication systems.

AbstractA planar inverted F-Antenna with the dual band-dual polarization property is presented for medical body area networks applications. The designed antenna covers the 2.45 GHz industrial, scientific and medical, 4 G long term evolution (2.5–2.69 GHz) bands for ON body communication and Wi-Fi and WLAN (3.5–3.6 GHz) bands for OFF body communication. At the lower band, an equivalent offset fed magnetic microstrip type dipole has been utilized that generate field parallel to the surface of the body for supporting ON body communication. The broadside radiation pattern has been realized using the slotted patch counterpart for supporting OFF body communication. This technique has resulted in a design of dual band dual mode property using a single radiator. The footprint of the antenna is only 0.35λg × 0.17λg × 0.08λg. Owing to its compactness, lightweight, and easy mountable property (due to foam substrate), the proposed antenna is found to be robust for MBAN applications. The maximum permissible transmitted power for the 1st band is 25.78 and 20.3 dBm for the 2nd one to maintain standard specific absorption rate limitations of 1.6 W/Kg. Experimental investigations over human body showed minimal deviations from the free space conditions which makes it a potential candidate for body-centric communications.

A compact dual-band dual-polarized wearable antenna for on-body communication in the 2.45 and 5.8 GHz ISM bands is presented. The antenna is linearly polarized (LP) at 2.45 GHz and circularly polarized (CP) with the conical pattern at 5.8 GHz, which is suitable for the multisensor link network. By using the characteristic modal analysis initially, the ground plane has been miniaturized and optimized to radiate an omnidirectional beam in the horizontal plane with the excitation of the lambda/4 resonant mode. The higher order band at 5.8 GHz has been realized by the excitation of the 3 lambda/4 resonant mode of the same L-shaped slot. These two odd-order modes radiate horizontally polarized omnidirectional patterns. The combination of the vertical polarization generated from the top-loaded patch antenna along with the 3 lambda/4 mode from the L-shaped slot resulted into omnidirectional CP in the 5.8 GHz band. Furthermore, enhancement in axial ratio bandwidth is achieved with the addition of dielectric superstrate over the feed layer. Bending sensitivity study to emphasize for conformal applications, transmission loss along with specific absorption rate analysis has been performed for on-body characterization. The simulated and measured results are found to be in good agreement.

A broadband circularly polarized (CP) planar monopole antenna is proposed here for ultrawideband (UWB) communication. The antenna is composed of a modified annular ring patch fed by a tapered microstrip line and a rectangular semiground plane on the opposite side of the substrate. Capability of generating wide axial ratio bandwidth (ARBW) is another feature of the proposed antenna. Wide ARBW is achieved by introducing a rectangular slot and a stub in the ground plane. The CP antenna has an impressive ARBW of 5.52 GHz (81.42%, 4.02-9.54 GHz) within the UWB frequency range (3.1-10.6 GHz). Measured 10-dB return loss bandwidth of the proposed antenna is 120.86% centered at 7.48 GHz (2.96-12 GHz). The proposed antenna is well used for wireless local area network (5.2 and 5.8 GHz), Worldwide Interoperability for Microwave Access (5.5 GHz), and other wireless systems in C band as well as CP-UWB antenna communication.

In this paper, a compact and wideband open-slot circularly polarized antenna is proposed. The proposed antenna based on microstrip line fed inverted L-shaped radiator and modified ground plane. The ground plane is modified by incorporating an inverted L-shaped grounded strip and etched a rectangular portion from the lower right corner. Therefore, a wideband circular polarization(CP) coverage is obtained within a compact size. The magnitude and phase differences between the two field components (E X , E Y ) can be controlled effectively by properly tuning the dimensions of the horizontal section of the inverted-L shaped radiator. Which is helpful to minimize the axial ratio (AR) values (≤3dB) to widening the ARBW over the C-band. The overall dimensions of the prototype is only 22×22×1.6 mm 3 . The simulated impedance bandwidth (IBW) is 17.86% (5.15-6.16GHz) and a 3-dB AR bandwidth is 24.61% (5.06-6.48GHz). A peak gain of 3.8dB is achieved within the ARBW. The proposed antenna is suitable for circular polarization applications in C band.

A dual band antenna operating at 2.45 and 5.8 GHz ISM bands is proposed for wearable applications. The antenna is simple in design where a coplanar waveguide (CPW) fed structure along with a slot in the patch are responsible for generation of dual band property. As the wearable antenna works in close proximity of the human body so, it is susceptible to various performance degradations. In order to restore the antenna performance, a fully flexible artificial magnetic conductor (AMC) based ground plane is placed beneath the antenna which is found to enhance the front to back ratio, gain and efficiency of the standalone antenna. Additionally, it reduces the specific absorption rate (SAR) of the antenna which is a merit from the wearable point of view.

A compact wideband coplanar waveguide (CPW)-fed antenna is designed for body implantable applications. The proposed antenna has an electrical dimension of only 0.42x0.42x0.0072 at 2.3GHz resonating frequency. Fractional bandwidth of 93.5% (1.35-3.5GHz) is achieved with the low-profile antenna. To understand the extent of miniaturisation and bandwidth enhancement of the antenna, the characteristic modal analysis is performed. The wideband feature is achieved with the application of asymmetric complementary split-ring resonator structure through multiple mode excitations. Additional miniaturisation and impedance matching are obtained with a pair of asymmetrical arc-shaped annular ring slots within the main radiator. The substrate and radiator have been realised using silicon and gold due to their inherent property of excellent bio-compatibility with the human body. Single layer, as well as multi-layers phantom model, was used to assess the performance of the antenna. Owing to the inherent wideband feature of the designed antenna, it is able to cover the desired band efficiently even after detuning in different phantom models. The designed antenna is tested in vitro with the development of proper muscle mimicking liquid and the measured results are found to be in good agreement with the simulated ones.

A novel dual band textile antenna for ON body communication in the 2.45 and 5.8 GHz ISM bands is presented. The overall size of the antenna is 60 x 30 x 3.75 mm(3) and the merit of the antenna lies in its design simplicity. To realize a small antenna size, the lower resonant frequency is generated by the ground plane which is larger than the radiator normally. The ground plane has been miniaturized with the addition of two alternate quarter wavelength slots placed parallel to each other. Through characteristic modal analysis, the ground plane of the antenna is optimized for radiating field parallel to the body which could facilitate ON body communication. The patch at the top has been folded in opposite directions to resonant at higher frequency. An equivalent circuit showing the working mechanism of the ground and the patch is shown. Simulation results were verified by measurement for the given antenna.

In this paper a combination of rectangular and staircase fractal curves are applied on a regular hexagonal wide slot antenna to achieve Super Wide Band (SWB) operation. The antenna is fed by a simple microstrip line along with a regular hexagonal tuning stub. The proposed antenna achieves a ratio impedance bandwidth 20:1 (from 3GHz to 60GHz) for VSWR ≤ 2. The bandwidth enhancement of the hexagonal wide slot antenna due to the fractal curves is shown in a step by step manner. Relatively stable omnidirectional radiation pattern and satisfactory value of gain is obtained over the operation band.

A novel compact CPW (coplanar waveguide-fed) CPSS (Circularly polarized square slot) antenna is presented. The proposed single-layer antenna is composed of a rectangular ground plane embedded with two equal-size patches along two orthogonal directions. Equal amplitudes with 90 phase difference values of two patches are capable of generating a resonant mode for exciting two orthogonal E vectors. Axial ratio (AR) bandwidth is significantly enhanced due to slot corner modification. The designed CPSS antenna is compact in nature with volume of 0.37 lambda(0) x 0.34 lambda(0) x 0.012 lambda(0) mm(3) (lambda(0) = free space wavelength at centre frequency of the CP bandwidth). It has impedance bandwidth between 4.65-6.72 GHz (36.41%) and 3-dB axial-ratio bandwidth of 520 MHz (4.85-5.37 GHz), which covers 4.9 GHz (802.11j) WLAN for public safety ranging from 4.94 GHz to 4.99 GHz and WLAN (U-NII-1 and U-NII-2A) ranging from 5.150-5.350 GHz for indoor use. The gain variation for the frequencies within the CP bandwidth is also observed to be less than 0.4 dBic. The design is successfully implemented, and measured results are compared with the simulated ones, which are found good agreement.

A compact dual mode dual wide band antenna for ON/OFF body communication is presented. The antenna comprises a circular patch which is electromagnetically coupled with an annular ring patch antenna. The TM11 modes of both annular ring and circular patch radiators are broadside directed whereas the TM21 modes of both have a radiation parallel to the human body. Wideband characteristic over the higher band has been achieved by tuning the TM21 modes of both the circular patch and annular ring while proper tuning of the fundamental modes of the two counterparts resulted into realization of lower wide band. Additional bandwidth and impedance matching is obtained with the help of an open ended rectangular slot cut over the annular ring patch and a shorting pin connected to the circular patch from the ground.

This paper presents a CPW fed dual-band dual-sense circularly polarized (CP) square slot antenna. The proposed antenna consists of a rectangular radiator with two unequal rectangular strips, connected by a CPW feed line and an asymmetric T-shaped stub is placed in the right side of the slotted ground plane with the orthogonal direction of the feed line. The proposed antenna obtained two CP bandwidth from 3.72GHz-4.14GHz (LHCP) and 5.3GHz-6.06GHz (RHCP) with axial ratio (AR) value less than 3dB and both the CP band are overlapped by impedance bandwidth of the antenna, ranging from 3.7GHz-7.15GHz. Design procedures of the antenna are discussed in details for further understanding of the antenna design. Total size of the proposed antenna is 50×50×1.58mm 3 . The antenna is fabricated on FR4-epoxy substrate and measured results are discussed in details.