Low-profile Planar inverted-F Antenna Research Articles

Compact PIFA Antenna with High Gain and Low SAR Using AMC for WLAN/C-band/5G Applications

In this paper, a novel low profile planar inverted-F antenna (PIFA) with high gain and low specific absorption rate (SAR) using a miniaturized artificial magnetic conductor (AMC) is investigated. The performance of the PIFA antenna is analyzed with AMC to understand the contribution of AMC. The gain enhancement of the PIFA antenna is achieved by applying AMC below the antenna. Furthermore, the placement of AMC also reduces the SAR of the antenna and improves the antenna front-to-back ratio (FBR). The proposed antenna when measured has an impedance bandwidth of 4.8–6.7 GHz (33% with center frequency at 5.75 GHz) which is suitable for Wireless Local Area Network (WLAN), satellite uplink C-band, and sub-6 5G applications with the maximum gain of 7.6 dBi. The performance of the proposed antenna is analyzed by full-wave commercial electromagnetic software and verified by measurements.

A Low-Profile Wide-Bandwidth Planar Inverted-F Antenna Under Dual Resonances: Principle and Design Approach

A low-profile planar inverted-F antenna (PIFA) under the operation of TM0,1/2 and TM2,1/2 modes in a single patch resonator for bandwidth enhancement is proposed. Initially, our study demonstrates that all of the even-order modes can effectively be suppressed by employing a rectangular PIFA instead of the conventional microstrip patch antenna. Then, a pair of shorting pins is appropriately loaded underneath the side-shorted radiating patch to investigate the variation of their odd-mode resonant frequencies. The results indicate that the resonant frequency of TM0,1/2 mode ( $f_{0,1/2}$ ) is dramatically increased up while almost maintaining that of TM2,1/2 mode ( $f_{2,1/2}$ ). After that, the width of the radiating patch is progressively enlarged in order to move the $f_{2,1/2}$ more closely to the $f_{0,1/2}$ . By using this approach, the dual radiative resonant modes can be reallocated in proximity to each other. Additionally, a narrow slot is etched out on the radiating patch so as to counteract the equivalent inductance caused by the shorting pins and probe. As such, a wide-bandwidth with stable radiation pattern is achieved for the PIFA under the operation of these dual-resonant modes. After the extensive analysis is executed, the proposed antenna is fabricated and tested. Simulated and measured results are found in good agreement with each other, demonstrating that its impedance bandwidth is tremendously widened to about 15.3% with appearance of two in-band attenuation poles. In particular, a low-profile property with the height of 0.036 free-space wavelength is achieved.

Design of ultrawide band planar inverted-F antenna with slotted broad feed

This article presents a low-profile planar inverted-F antenna (PIFA) for broadband applications. The proposed antenna geometry is simple and does not use any parasitic elements, which makes its fabrication easier. The antenna's radiator is composed of a top loading plate, broad feed plate, and a shorting plate; occupies a total volume of (L × W × H) 20 × 12 × 6 mm3. The proposed antenna design achieved the wideband characteristics by using the method of bringing resonances to proximity; furthermore, the low-profile feature is achieved by removing some portion of the ground plane according to the volume ratio of PIFA. To validate the simulated results, an antenna prototype has been fabricated. The simulated and measured radiation patterns, gain, group delay, and simulated peak-specific absorption rate (SAR) are presented. The measurement result demonstrates that the proposed antenna design achieved the maximum bandwidth of 142% (3.1–18.5 GHz) for |S11| ≤ −10 dB.

Low-Profile Planar Inverted-F Antenna for Ultrawideband Applications

In this paper, a low-profile planar inverted-F antenna (PIFA) for ultrawideband (UWB) applications is proposed. The antenna consists of a PIFA and a ground plane with a slot. The addition of the slot not only improves the impedance matching of the PIFA but also forms an additional resonance. Therefore, the proposed antenna has a wideband characteristic covering the full UWB frequency range (3.1 GHz to 10.6 GHz) and a stable and nearly omnidirectional radiation pattern. The antenna also has a smaller volume and thickness compared to previous UWB PIFAs.

Design of multiband PIFA with low SAR value for all commercial mobile communication bands

A low profile planar inverted-F antenna is proposed for mobile handset applications. Thus, our target is to introduce a new antenna that supports both services, the proposed antenna have broadband characteristic which includes all commercial service bands, GSM850/GSM900/GPS/GSM1800/GSM1900/WCDMA2100/802.11b/g/LTE2600 (824–2690 MHz) as well as 802.11a/n (5150–5825 MHz). Overall size of the antenna is 21 × 45 × 8 mm3 is well suited for mobile handsets due to its low profile, small size, wide bandwidth, the radiation patterns are satisfactorily omnidirectional across the antenna's operation bands, and good gain (the gain in some frequency bands is higher than 4 dBi). The antenna not only has a compact size, but also it supports a low specific absorption rate (SAR) radiation at all the operating frequencies. In addition, the proposed antenna is assessed using the finite difference time domain (FDTD) program written with MATLAB to validate the results. The antenna meets three challenging parameters: the compact size, the multiband operation including the low frequency bands, and the low SAR radiation. The measured results exhibit good agreement with the simulation results from CST and the FDTD program written with MATLAB. As a result, the designed antenna is suitable for small mobile devices and slim wireless applications. © 2014 Wiley Periodicals, Inc. Int J RF and Microwave CAE 25:194–201, 2015.

Small Multi-Band Antenna with Tuning Function for Body-Centric Wireless Communications

The research on body-centric wireless communications (BCWCs) is becoming very hot because of numerous applications, especially the application of E-health systems. Therefore, a small multi-band and low-profile planar inverted-F antenna (PIFA) with tuning function is presented for BCWCs in this paper. In order to achieve multi-band operation, there are two branches in the antenna: the longer branch low frequency band (950-956MHz), and the shorter branch with a varactor diode embedded for high frequency bands. By supplying different DC voltages, the capacitance of the varactor diode varies, so the resonant frequency can be tuned without changing the dimension of the antenna. While the bias is set at 6V and 14V, WiMAX and ISM bands can be covered, respectively. From the radiation patterns, at 950MHz, the proposed antenna is suitable for on-body communications, and in WiMAX and ISM bands, they are suitable for both on-body and off-body communications.

Critical coupling of the inverted‐F antenna by increasing effective inductance

AbstractIn this letter, a novel feed structure that can achieve critical coupling in a planar inverted‐F antenna (PIFA) is proposed.The proposed structure considerably increases the effective inductance simply by inserting a branch capacitance between the feed line and the shorting pin of the conventional planar inverted‐F antenna without structural change to the antenna or ground plane. The extremely low profile PIFA for the GSM900 band is designed to verify the proposed feed structure for critical coupling. The designed PIFA fully covers the GSM 900 band for VSWR < 3. Also, a good omnidirectional radiation pattern was obtained at its operating frequency. © 2011 Wiley Periodicals, Inc. Microwave Opt Technol Lett 53:737–740, 2011; View this article online at wileyonlinelibrary.com. DOI 10.1002/mop.25839

An RFID Tag Using a Planar Inverted-F Antenna Capable of Being Stuck to Metallic Objects

This letter presents the design for a low-profile planar inverted-F antenna (PIFA) that can be stuck to metallic objects to create a passive radio frequency identification (RFID) tag in the UHF band. The designed PIFA, which uses a dielectric substrate for the antenna, consists of a U-slot patch for size reduction, several shorting pins, and a coplanar waveguide feeding structure to easily integrate with an RFID chip. The impedance bandwidth and maximum gain of the tag antenna are about 0.3% at 914 MHz for a voltage standing wave ratio (VSWR) of less than 2 and 3.6 dBi, respectively. The maximum read range is about 4.5 m as long as the tag antenna is on a metallic object.