A small planar inverted F antenna with capacitive and inductive loading

A spherical ultra-wideband antenna is proposed based on a self-complementary structure. The antenna employs a loop comprising two symmetric teardrop-shaped arms conformally printed on a three-dimensional (3D) sphere. To enhance the impedance matching bandwidth, inductive and capacitive loadings are applied to the antenna by adding shorting strips at the antenna’s rear part and broadening the front part respectively. Measurement results show that the proposed antenna is capable of covering the frequency range of 0.8–8 GHz with a low reflection coefficient(S11) ≤ − 10 dB, gain > 2.8 dB, and radiation efficiency > 63%.

Inverted-F antennas (IFAs) are a primary choice to implement the radiating system of portable devices. A tried and tested idea can remain topical if proven useful in modern applications. This paper shows that printed IFAs (PIFAs) are capable of forming robust, compact, dual-band radiating systems for wireless microsensors with an adjustable spacing between bands. Reactive tuning was applied by inductively loading the structures with prefractal slots; inductive slot loading degenerates higher-order resonances and increases the fractional bandwidth (FBW). The current distributions revealed that most of the element area is used for radiation at both resonances. In radiation terms, the antennas provide satisfactory gains and high efficiencies (≥82%). A simple figure of merit is used to compare the performance of the three PIFAs head to head. Operation at 2.5 GHz and 5.5 GHz indicated that changes in slot geometry almost double the FBW. The proposed antennas serve both the 5.15–5.35 GHz U-NII and the 5.8 GHz ISM bands; at the lower band, their size is less or equal to the half-wavelength dipole. This study of dual-band antennas also showed that the aggregate FBW of a PIFA is bounded; by degenerating higher-order modes, the designer redistributes whatever bandwidth is available by the antenna itself to the desired bands.

A study of the efficiency of small dipole antennas loaded with a left-handed transmission line is described. The antenna is composed of a ladder network periodic structure of a number of unit cells. Left-handed performance can be obtained in straight or meandered capacitive-inductive (CL) lumped loading. Its performance is compared to a right-handed dipole with inductive (L) lumped loading. Differently loaded dipoles with four unit cells with the same size reduction have been compared. Right-handed loading gives the best efficiency as expected, but left-handed loading shows the greater degree of freedom to achieve a desired impedance at the terminals. The efficiency is also increased when the CL-loaded dipole is meandered, because of the higher radiation resistance. Moreover, different numbers of unit cell have been compared in order to clarify the number for the best efficiency with size reduction. In a low-order mode, an inductively loaded dipole has highest efficiency for two unit cells, with reduced efficiency with the number of loading elements. However, the reverse is true for the CL-loading. The efficiency of a meandered CL-loaded dipole becomes comparable to the conventional L-loading for higher than four cells. CL-loading with higher mode number gives higher efficiency than a conventional dipole with multiple inductive loads.

Periodic coplanar waveguides (CPWs) with inductive loading are thoroughly studied by resorting to unit-length transmission parameters, i.e., propagation constant and characteristic impedance, of an equivalent dispersive and/or lossy transmission line. The admittance-type method of moments (MoM) is at first formulated to full-wave modeling of a finite-cell periodic CPW with the two feeding lines and then the short-open-calibration procedure is carried out to deembed the two-port ABCD matrix of the core periodic CPW section. Thus, the above two parameters can be extracted from the MoM simulation to exhibit their guided-wave characteristics, i.e., slow-wave and bandstop behaviors. It is demonstrated for the first time that, within the bandstop or bandgap, the propagation constant must become complex with a nonzero attenuation constant, while the characteristic impedance appears purely imaginary. Three periodic CPW circuits with six finite cells are then characterized on a basis of the transmission-line theorem and the derived S-parameters are validated by Momentum simulation and RF measurement.

This study intends to discuss enclosed a realistic approach to determine and analyze the effects of radio frequency on human exposure inside a cylindrical enclosure. A scenario in which a mobile phone with inverted-F antenna (IFA) operating in the Global System for Mobile Communication (GSM) band (900 MHz) is used inside a cylindrical enclosure. Metallic enclosures are known to have resonance and reflection effects, thereby increasing electric field strength and hence resulting in a change of the human exposure to electromagnetic absorptions. So, this study examines and compares the levels of absorption in terms of specific absorption rate (SAR) values under various conditions. In this study, a human phantom with dielectric properties is designed and its interaction is studied with IFA inside fully enclosed cylindrical enclosures. The results show that SAR values are increased inside cylindrical enclosures compared with those in free space. The method of computation uses method of moments. Simulations are done in FEKO software.

Because the Josephson pair current in a weak-link superconductor junction is a nonlinear parametric function of junction voltage, the ac impedance seen by the junction influences both the response time to changes in bias and the dc voltage-current characteristics. The first effect is obvious; the second, considered here, has not been generally recognized. Both are relevant to device design. Two special cases which illustrate the basic principles involved are worked out in detail; they correspond, respectively, to ac capacitive and inductive loading. The results partly explain differences in the dc voltage-current characteristics of plane-parallel and point-contact junctions.

A generic integrated optoelectronic-to-VLSI packaging technology using silicon substrate and etched silicon optical submount has been developed and demonstrated. The miniature silicon submount that interfaces optical fiber with the optoelectronic component and the silicon substrate containing VLSI circuits is fabricated with double-sided nonplanar photolithography and anisotropic etching techniques. The advantages of this technology are: ability to interface optical information and circuits with VLSI in a single package; precision controlled capacitive, resistive, and inductive loading; minimized distance between optoelectronic components and electronic ICs, and between decoupling capacitors and active circuits; self-aligned fiber insertion; and highly automated manufacturing. These advantages translate to higher functional density and performance at a lower cost than conventional optoelectronic packaging technologies. >

Planar antenna modeling requires a constrained solution space and open boundaries and so is highly computationally intensive. One of the methods used to overcome this is by using method of moments simulation. The method of moments is a highly efficient method of solving wire antenna structures and is commonly used in antenna optimization. A method of transforming a wire antenna structure to a planar antenna structure is presented using a 4‐element Yagi‐Uda antenna designed to resonate at 905 MHz. The wire to planar transformation is based on the circular cross section wire to planar strip, a spacing adjustment based on interelement capacitance, and a length scaling to compensate for the change in effective permittivity. The planar antenna shows slightly improved impedance performance at the resonance [voltage standing wave ratio (VSWR) = 1.39]. This transformation decreased the antenna footprint by 15.11% after conversion for a wire antenna to a planar antenna in air with similar radiation characteristics and on FR4 (1.6 mm thickness), the footprint increased by 52%. The antenna simulation time was reduced from 15 min using finite element method to less than 10 s for one cycle by using the method of moments solver. All antenna properties are essentially unchanged. © 2013 Wiley Periodicals, Inc. Int J RF and Microwave CAE 24:184–190, 2014.

A capacitively loaded planar inverted-F antenna (PIFA) is proposed and studied. It is found that the capacitive load reduces the resonance length of the PIFA from /spl lambda//4 to less than /spl lambda//S. A design with a bandwidth of 178 MHz centered at 1.8 GHz is provided to demonstrate that compact antennas for mobile telephone handsets can be constructed using this approach. The finite-difference time-domain (FDTD) method is used in the study and experimental verification is also provided.

This paper presents a dual Subscriber Identity Module (SIM) mobile phone which integrates a planar inverted-F antenna (PIFA), a monopole, and an inverted-F antenna (IFA). The main circuit board of the mobile phone has a dimension of 105 mm × 45 mm. By optimizing the multi-antenna configuration and adjusting the gap and angle of the antennas, good isolations of the three antennas are obtained. The PIFA and monopole support the Global System for Mobile communications (GSM) applications. And the measured results show that the Total Radiated Power (TRP) and Total Isotropic Sensitivity (TIS) of them satisfy the Cellular Telecommunications and Internet Association (CTIA) requirements. In addition, the IFA which enables the Bluetooth achieves a 3.79 dB gain. The presented ways are very useful for the dual SIM mobile phone design.

By embedding a group of parallel slots in the ground plane, novel dual‐frequency operations of a single‐feed planar inverted‐F antenna (PIFA) are presented. Simulation based upon the method of moments (MoM) is used to model the performance of the antenna. An example of the proposed antenna is fabricated to validate the simulation, and the experimental results show that the 10‐dB return‐loss impedance bandwidths are about 9% and 8.4% for frequency bands of 1.9 and 2.4 GHz, respectively. In addition, the measured radiation patterns in the two frequency bands are similar to that of a conventional planar inverted‐F antenna. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 39: 72–75, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.11131

In this paper a planar broad-band antenna, which can be used as a ground penetrating radar, is designed by a combination of a genetic algorithm (GA) and a method of moments (MoM) technique. The GA optimizes the shape of the metallisation pattern in order to minimize the return loss in the chosen frequency band of 1-6 GHz, while the return loss is evaluated with a MoM-analysis. The optimization is made more efficient by applying the direct matrix manipulation (DMM) method. In order to distinguish symmetric and non-symmetric objects, an antenna which detects cross-polarization is used.

A periodically loaded ultra wideband (UWB) bandpass filter based on the electromagnetic band-gap (EBG) concept is presented. Compact wideband filters with steep transition bands can be designed easily using this novel methodology. Unit cells in the EBG circuit model are realized by capacitive and inductive parallel loading of a transmission line. These unit cells are cascaded to realize bandpass filters whose bandwidth depends on the reactive loading of unit cells. The number of unit cells determines the steepness of the band edges of the filter. The main advantage lies in the fact that the size of unit cells can be small because electrical length of transmission line segments in unit cells can be chosen arbitrarily, hence the final filter structure becomes small in size. A microstrip filter with 60% bandwidth is designed and the physical size is compared with a conventional wideband bandpass filter designed with quarter wavelength admittance inverters.

Achieving the high data rates proposed by the fourth generation (4G) technology using a small-size antenna on a compact device remains a major technical challenge. This paper focuses on surveying the ongoing researches on antenna design for USB dongle supporting Long Term Evolution (LTE). This article analyses the advantages and disadvantages of the alternatives of small monopole antenna design such as meandered line antenna, inverted-L antenna, inverted-F antenna, planar inverted-F antenna, and multiband antenna composed of different types of radiators for providing multifunctional operations for LTE-USB antennas. Based on isolation techniques, multiple-input multiple-output (MIMO) techniques implemented has been classified and analysed. The finding is that the existing work focused on the wire or 3D antennas and still there are voids for researchers to improve the low cost, and simple profile printed antenna designs. LTE MIMO throughput measurement for characterization of antenna terminal performance study is absent from all reviewed papers contained in this study.

A new type of antifading broadcast antenna, consisting of typically four base-excited sloping wires located symmetrically about a central insulated support mast, offers significant advantages over conventional loaded antifading radiators. These advantages include a higher loop radiation resistance for mast heights below approximately 0.4λ, less inductive loading, and multiple parallel earthing points that are expected to reduce the earth losses when the soil is of low conductivity. The radiation resistances and associated antifading radiation patterns have been computed using two techniques; one with assumed sinusoidal-current distributions on the sloping wires and assumed negligible induced mast currents. The other involved a moment method analysis employing subsectional bases for the wire and mast currents. Results given by the first method agree well with both measurements performed on models having a nonmetallic mast, and the predictions given by the second method for masts having three or four insulated sections. If only two insulated mast sections are employed the induced mast current lowers the radiation resistance significantly; whereas, with a single continuous conducting mast section, the radiation pattern loses the required antifading form. It is considered that the new antenna will lower the minimum practical height of antifading radiators from the present value of approximately 0.35λ for conventional loaded monopoles to somewhere in the range 0.25λ to 0.3λ.