H-shaped Slot Antenna Research Articles

H-Shaped Slot Antenna with Harmonic Tuning Function and Integrated Power Amplifier

This study proposes a patch antenna with an H-shaped slot with direct matching and harmonic tuning (rejection) functions for microwave power transfer. This antenna enables an integrated active antenna in which the power amplifier and antenna are directly connected without using a matching circuit for the fundamental frequency and harmonic rejection filter to improve the efficiency of the amplifier. The integrated design also reduces the total size of the amplifier and antenna, allowing for a higher-density array antenna. Characteristic mode analysis was performed to explain the working principle of the harmonic rejection function. The designed antenna at 5.8 GHz was fabricated to study its harmonic tuning function. The magnitude of the reflection coefficient of the proposed antenna was at a fundamental frequency of −40.4 dB for an amplification device with an optimum load impedance of 100 Ohm. At the second harmonic frequency, the magnitude and phase of the reflection coefficient at the second harmonic frequency were −0.79 dB and −177.6°, respectively; at the third harmonic frequency, they were −0.92 dB and −179.5°, respectively. Finally, the designed antenna was integrated into an amplifier circuit to verify that it achieved similar drain efficiency as when using the impedance tuner. It was confirmed that the harmonic rejection function of the proposed antenna increases the drain efficiency of the integrated power amplifier by 5.5%. The measurements revealed that this antenna is suitable for use in microwave power transfer because of its fundamental matching and harmonic-processing capabilities.

Energy Harvesting Rectenna Design for Enhanced Node Lifetime In WSNs

With the rising popularity and advent of many services on Wireless Sensor Networks (WSNs), there is a compelling need to have energy-efficient solutions. The sensors and devices are powered by batteries whose life is limited, and at times it is impossible to replace the batteries, especially in remote applications. In such a scenario, Energy Harvesting (EH) stands as an undisputed candidate for enhancing the network lifetime. Radio Frequency (RF) energy is the most commonly available, ubiquitous, and reliable energy source among all the available energy sources. While RF signal carries both information and energy, EH is possible for long-distance and mobile environments. This work discusses initial research in the domain of EH in wireless networks via Radio Frequency (RF) signals. The paper presents an EH rectenna for energy harvesting over 2.45 GHz (Wi-Fi band). The receiving antenna is designed to pick up the radio signal in the RF range (2.45 GHz) from the free space. The four patch elements design has an antenna substrate made with RT with a dielectric constant of 2.2. The paper presents the simulation results of the basic parameters of the antenna, such as return loss, input impedance, bandwidth, gain, directivity, and efficiency. H-shaped slot antenna and modified H-shaped antenna (with circular slot) are designed with a gain of 8.24 dB and 8.32 dB, return loss of -10 dB and -16 dB, and bandwidth of 64.8 MHz and 868 MHz. The high gain, large bandwidth, properly matched impedance for minimum return loss, and high efficiency of the modified H-shaped patch antenna makes it eligible for energy harvestin.

Body-Matched Gradient Index Lens Antenna for Electromagnetic Torso Scanner

A lens antenna that performs both as a matching medium and as a spherical-to-planar wave transformer for near-field electromagnetic medical scanning is presented. By achieving those two main targets, the antenna, which can be classified as body-matched gradient index (GRIN) lens, maximizes signal penetration and forms a focused plane wave incident field distribution inside the torso. Consequently, it improves image quality in electromagnetic imaging (EMI) applications. A design process is proposed based on the theory of multilayer medium with different dielectric properties. To realize the obtained dielectric values, the structure is 3-D printed in a planar structure comprising multiple sets of holes forming four layers. Each row has eleven holes with different radii that are filled with freshwater to create four distinct permittivity layers. The fabricated lens is illuminated using an H-shaped slot antenna. It is tested on a torso phantom that is comprised of skin and fat layers and torso tissue-mimicking mixture. The GRIN lens antenna achieves a wide fractional bandwidth of 53% at 0.78–1.34 GHz with a size of <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$130\times 130\times53.6$ </tex-math></inline-formula> mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> ( <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$0.3\lambda _{0}\times 0.3\lambda _{0}\times 0.14\lambda _{0}$ </tex-math></inline-formula> , where <inline-formula xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> <tex-math notation="LaTeX">$\lambda _{0}$ </tex-math></inline-formula> is the wavelength at the lowest operating frequency). The lens structure improves the signal penetration at the center of the torso by 6 dB compared to a standard slot antenna. Moreover, the electric field intensity can be steered inside the torso phantom by controlling water level in the created holes.

Design and Simulation of a Compact 5.4GHz H-shaped Slot Antenna for RF Energy Harvesting Systems

in this paper, a compact H-shaped slot antenna is proposed. The antenna contains one H-shape slot which is fed through microstrip line, an open circuited stub is connected for proper impedance matching. The H- shaped slot is used for bandwidth enhancement. The antenna is designed to radiate at 5.4 GHz with a bandwidth of 1.6GHz. The antenna has an omni-directional pattern across the frequency band. The gain of the antenna is 4.35dBi at 5.4GHz. Since, the proposed antenna satisfies all the characteristics of energy harvesting systems, it can be used for energy harvesting systems, at 5.4GHz 4G-LTE band. CST microwave studio was used for designing the proposed antenna. An excellent agreement is achieved between simulated and measured results.

Compact 5.4 GHz H-Shaped Slot Antenna for Energy Combining

Compact 5.4 GHz H-Shaped Slot Antenna for Energy Combining

Wideband Epidermal Antenna for Medical Radiometry.

Microwave thermometry is a noninvasive and passive technique for measuring internal body temperature. Wearable compact antennas, matched to the specific body area, are required for this method. We present a new epidermal wideband antenna for medical radiometry. The double asymmetric H-shaped slot antenna was designed to be matched to different parts of the body without fat layers. The slots are fed by a short-circuited microstrip line in order to decrease size and back radiation, thus reducing potential interferences. In this way, contribution to radiometric temperature due to back radiation is lower than 4%, versus the 20% of the volume under investigation, over the whole operating frequency band. The designed prototype was manufactured on a flexible substrate. The antenna is a very small size, to make it comfortable and suitable for being used by patients with different body mass indexes. The double H-shaped antenna shows good wideband matching results from around 1.5 GHz up to 5 GHz, in different body locations such as the neck, foot instep and foot sole.

Bandwidth Enhancement of a Dual-Polarized Slot Antenna Using Characteristic Modes

In this letter, a wideband dual-polarized slot antenna is presented. The proposed antenna is designed in a systematic way using the theory of characteristic modes for slot apertures. An H-shaped slot in an infinite ground plane is used as the initial structure for further optimization design. Magnetic characteristic currents for the first four modes of the slot are investigated. To enhance the bandwidth (BW) of the antenna, the geometry of the slot antenna is then modified based on the clear physical insights obtained from the modal analysis. In addition, two pairs of differentially fed capacitive coupling elements are introduced to excite the first two modes of the slot, and an integrated wideband feeding network is designed. An antenna prototype in WLAN 2.4 GHz band is fabricated. Experimental and simulated results show that the proposed dual-polarized slot antenna has a wide BW and good dipole-like radiation characteristics. Compared with the initial H-shaped slot antenna, the BW of the proposed antenna is enhanced from 17% to 46%. The measured port isolation over the entire frequency band is about 26 dB, and the cross-polarization level is over 28 dB for the two polarizations.

Modified H-shaped Microstrip Array Antennas for WiMAX Applications

Modified H-shaped array antennas are proposed to achieve high gain and good impedance matching for WiMAXapplications. Here a 3*2 H-shaped microstrip array antenna is designed. To reduce the return loss and for good impedance matching, the 50 ohm impedance transformer is used. By using H-shaped slot antenna, an air bridge can be avoided in design as well as the complexity of design can be reduced .The 180 degree phase shifters are organised in H-shaped antenna. It gives 7.77 dB gain and 11.97 dB directivity. The return loss of 16 dB and 24 dB can be achieved at 3.3 GHz and 3.7 GHz operating frequencies which are WiMAX frequencies. Index Terms:Modified H-shaped antenna, WiMAX, 50 ohm impedance transformer, 180 deg phase shifter.

Compact Multi-Band H-Shaped Slot Antenna

A compact triple-band H-shaped slot antenna fed by microstrip coupling is proposed. Four resonant modes are excited, including a monopole mode, a slot mode, and their higher-order modes, to cover GPS (1.575 GHz) and Wi-Fi (2.4-2.485 GHz and 5.15-5.85 GHz), respectively. Sensitivity study of the slot geometry upon the resonant modes have been conducted. The measured gains at these four resonant frequencies are 0.2 dBi, 3.5 dBi, 2.37 dBi, and 3.7 dBi, respectively, and the total efficiencies are -2.5 dB, -1.07 dB, -3.06 dB, and -2.7 dB, respectively. The size of this slot antenna is only 0.24λ0×0.034λ0, where λ0 is the free-space wavelength at 1.575 GHz, hence is suitable to install on notebook PC's and handheld devices.

Large and Optically Transparent Multilayer for Broadband H-Shaped Slot Antenna

This letter presents a feasibility study of a large optically transparent broadband antenna for urban radio cellular networks. The proposed H-shaped slot antenna, which is well suited for antenna arrays, is made of three transparent and conductive layers printed on three glass substrates separated by two air gaps. The size of the antenna is close to 300×300×20 mm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3</sup> . The transparent and conductive coatings used to fabricate the antenna are made of a silver grid layer (AgGL) deposited on one side of each 1.1-mm-thick 1737 Corning glass substrate. The theoretical optical transparency of the multilayer antenna ranges between 51.6% and 70.7% over the whole visible light spectrum. The measured electromagnetic performance of the transparent H-shaped slot antenna has been compared to that of a nontransparent (but geometrically identical) simulated antenna. The results show a similar behavior and performance in terms of bandwidth, radiation pattern, and gain. This confirms the restriction of the ohmic loss and skin depth loss from the AgGL material. These also provide the ability to implement large transparent antennas with performance identical to that of nontransparent ones, and most importantly with the advantage of a soft visual impact on urban environment.

Dual‐band H‐shaped slot antenna for 2.4 and 5 GHz wireless communication

AbstractA simple and compact dual‐band H‐shaped slot antenna for wireless local area network applications is proposed.The proposed antenna is composed of an H‐shaped slot on the ground plane with size of 23 mm by 32 mm. The substrate material is foam. The antenna is fed by microstrip at its top. The impedance bandwidth, radiation pattern, and gain of the antenna were simulated. The results show that the antenna just covers the WLAN bands (2.4–2.485, 5.15–5.35, and 5.725–5.825 GHz), with the gain remaining steady. The measurement of impedance bandwidth was carried out with a network analyzer. A good agreement between measurement and simulation can be observed. © 2010 Wiley Periodicals, Inc. Microwave Opt Technol Lett 52:957–959, 2010; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.25042

Compact CPW-fed ground defected H-shaped slot antenna with harmonic suppression and stable radiation characteristics

A compact uniplanar antenna for 2.4 GHz WLAN applications is presented. This compact co-planar waveguide (CPW)-fed antenna has an advantage of excellent higher harmonic suppression. This characteristic is brought about by suitably inserting symmetrical slots in the ground plane of an open-ended CPW-fed transmission line. The proposed antenna with an H-shaped slot exhibits the characteristics of a centre-fed slot dipole together with excellent higher-harmonic suppression. The antenna designed on a substrate of dielectric constant 4.4 and height 1.6 mm offers moderate gain and good radiation characteristics. The design equations for the proposed antenna are validated in different frequency bands. Details of the simulated and experimental characteristics of the antenna are presented and discussed.

Dual-band CPW-FED Double H-shaped Slot Antenna for RFID Application

A novel double H-shaped slot is introduced to achieve a dual-band coplanar waveguide CPW-fed antenna for radio frequency identification (RFID) applications. The designed antenna is low in profile and can operate simultaneously at 2.45 and 5.8 GHz bands with 1.07 and 2.38 dBi gains, respectively. Also, good omnidirectional radiation patterns have been obtained. Its properties make the antenna not only suitable for RFID tags, but also for WLAN applications.