T. Peter

A Reconfigurable Wideband and Multiband Antenna Using Dual-Patch Elements for Compact Wireless Devices

A reconfigurable wideband and multiband C-Slot patch antenna with dual-patch elements is proposed and studied. It occupies a compact volume of 50 × 50 × 1.57 (3925 mm3), including the ground plane. The antenna can operate in two dual-band modes and a wideband mode from 5 to 7 GHz. Two parallel C-Slots on the patch elements are employed to perturb the surface current paths for excitation of the dual-band and the wideband modes. Two switches, implemented using PIN diodes, are placed on the connecting lines of a simple feed network to the patch elements. Dual-band modes are achieved by switching “ON” either one of the two patch elements, while the wideband mode with an impedance bandwidth of 33.52% is obtained by switching “ON” both patch elements. The frequencies in the dual-band modes can be independently controlled using positions and dimensions of the C-Slots without affecting the wideband mode. The advantage of the proposed antenna is that two dual-band operations and one wideband operation can be achieved using the same dimensions. This overcomes the need for increasing the surface area normally incurred when designing wideband patch antennas. Simulation results are validated experimentally through prototypes. The measured radiation patterns and peak gains show stable responses and are in good agreements. Coupling between the two patch elements plays a major role for achieving the wide bandwidth and the effects of mutual coupling between the patch elements are also studied.

Multiband Inverted-F Antenna With Independent Bands for Small and Slim Cellular Mobile Handsets

The design of a small ultra-thin printed inverted-F antenna (PIFA) with independent control on the resonant frequency bands is proposed. The antenna consists of a slotted radiator supported by shorting walls and a small ground plane. The structure is designed and optimized to operate at 2.09, 3.74 and 5 GHz with achievable bandwidths of 11%, 8.84% and 10%, respectively. These three bands cover the existing wireless communication frequency bands from 1.5-6.8 GHz. Each of the three bands can be controlled independently without affecting the other two bands. The 2.09 GHz band can be controlled to operate between 1.5-2.09 GHz (33.33%), the 3.74 GHz band can be controlled over the range of 3.57-4.18 GHz (15.76%) and the 5 GHz band can be controlled to cover the band from 5.00-6.80 GHz (30.50%). Results of intensive investigations using computer simulations and measurements show that the ground plane and the feed locations of the antenna have marginal effects on the performance of the antenna. The effects of the users hand and mobile phone housing on the return loss, radiation patterns, gains and efficiency are characterized. The measured peak gains of the prototype antenna at 2.09, 3.74 and 5 GHz are 2.05, 2.32 and 3.47 dBi, respectively. The measured radiation efficiencies for the corresponding three bands are 70.12, 60.29 and 66.24% respectively.

A Novel Technique and Soldering Method to Improve Performance of Transparent Polymer Antennas

A novel technique and a nonthermal soldering method to improve the performance of AgHT-8 transparent polymer antennas are proposed in this letter. The proposed technique involves the removal of the coating layer at areas on the coplanar waveguide (CPW) ground and feed line where the connectors of the coaxial feed or legs of the SMA connectors will be attached and applying a coat of silver paint on the exposed areas before cold-soldering the coaxial connections or SMA connector legs. The nonthermal or cold soldering using electrically conductive paste enables direct soldering of the coaxial feed points or connector legs, which cannot otherwise be done with hot or thermal soldering. This type of connection greatly enhances the performance of the AgHT-8 polymer antennas compared to coaxial feed point connections through hot-soldered copper pads glued to the surface of the polymer coating. The proposed technique also gives a stronger connection bond than directly cold-soldering the feed points or connectors to the smooth surface of the AgHT-8 material. Furthermore, the copper pad connection technique also introduces additional losses contributed by the adhesive properties of the glue used. This proposed novel technique and soldering method may be extended to enhance antenna performance made from other similar transparent conductive polymers like ITO.

A Novel Transparent UWB Antenna for Photovoltaic Solar Panel Integration and RF Energy Harvesting

A novel transparent ultra-wideband antenna for photovoltaic solar-panel integration and RF energy harvesting is proposed in this paper. Since the approval by the Federal Communications Committee (FCC) in 2002, much research has been undertaken on UWB technology, especially for wireless communications. However, in the last decade, UWB has also been proposed as a power harvester. In this paper, a transparent cone-top-tapered slot antenna covering the frequency range from 2.2 to 12.1 GHz is designed and fabricated to provide UWB communications whilst integrated onto solar panels as well as harvest electromagnetic waves from free space and convert them into electrical energy. The antenna when sandwiched between an a-Si solar panel and glass is able to demonstrate a quasi omni-directional pattern that is characteristic of a UWB. The antenna when connected to a 2.55-GHz rectifier is able to produce 18-mV dc in free space and 4.4-mV dc on glass for an input power of 10 dBm at a distance of 5 cm. Although the antenna presented in this paper is a UWB antenna, only an operating range of 2.49 to 2.58 GHz for power scavenging is possible due to the limitation of the narrowband rectifier used for the study.

Miniature transparent UWB antenna with tunable notch for green wireless applications

In this paper, the design of a UWB antenna using a transparent AgHT-8 material is proposed for green wireless applications. Computer simulation is used for studies. For verification of the design, the proposed antenna is fabricated on an AgHT-8 film and measured. Results show that the antenna has better radiation efficiency relative to its size than the previous designs, good omni-directional radiation patterns throughout the FCC bandwidth of 3.1–10.6 GHz and a comparable gain. To filter out the unwanted signals in the WLAN band, two vertical slots are introduced to produce a tuning notch in the 5 GHz frequency band. For demonstration of green wireless applications, the transparent antenna is incorporated with a solar panel for harnessing solar energy. Results show that the transparency of the antenna makes it a good candidate for future green wireless applications.

Compact dual-band (2.4/5.2GHz) monopole antenna for WLAN applications

A compact and optimized design of a rectangular printed monopole antenna with slits and truncated ground plane on FR-4 substrate is presented. The proposed antenna is designed for dual-band operation at 2.4 GHz and 5.2 GHz for Wireless Local Area Network (WLAN) applications with S11≪ −10 dB. This antenna has good return loss and radiation characteristics in required frequency band. The proposed antenna gives omni-directional radiation pattern in the E Plane and H plane over the frequency range of 2.4 GHz and 5.2 GHz. The calculated and measured results in terms of return loss show good agreement and the results also show good wideband characteristics.

PIFA based reconfigurable multiband antenna for wireless applications

A compact reconfigurable four bands Planar Inverted-F Antenna (PIFA) is presented for Digital Video Broadcasting — Handheld (DVB-H), Universal Mobile Telecommunications System (UMTS), Global System for Mobile Communications (GSM800, 900, 1800 and 1900), Personal Communications System (PCS), Wireless Local Area Network and Bluetooth (WLAN), Worldwide Interoperability for Microwave Access (m-WiMAX) and Hiperlan/2 applications. Two varactor diodes with variable capacitors are used to electrically tune the operating frequencies over a wide range. The overall size of the radiated parts is 31.5 × 30.5 mm2 which makes it easy to integrate it into small mobile handset. Depending on the voltage applied to the switches the operating frequencies at 0.7 GHz, 2 GHz, 3.5 GHz and 5 GHz can be tuned over 30.48%, 20%, 4% and 4% respectively. The peak gains for the four bands range −4dBi, 3dBi, 3dBi and 6dBi at DVB-H, UMTS, WiAMX and WLAN, respectively. The average efficiency of the four bands ranges from 95% to 85%. The radiation patterns and other discussions are provided.

A novel technique to improve gain in transparent UWB antennas

A novel technique to improve the performance of AgHT-8 transparent polymer antennas is proposed in this paper. A spit-ring resonator is introduced on the radiating patch to enhance gain. The resonator basically concentrates the radiating energy to the central area of the patch thus improving gain. The designed antenna demonstrates good gain while maintaining the original transparency of the material. Such an antenna inscribed on the commercially available AgHT-8 sun shielding film material makes it a viable option for wireless applications like in-house base stations and applications requiring fast data rate transfers which can be mounted on windows and glass panels.

Small and thin Inverted-F Antenna with insensitive ground plane for mobile handsets

A small ultr-thin tri-band Planar Inverted-F Antenna (PIFA) is presented. The proposed antenna consists of slotted radiated parts supported by shorting walls and a ground plane. Intensive investigations are carried out in this paper to show that the ground plane and the antenna locations have insignificant effect on the performance of the antenna while the physical height of the radiated parts can be more significant. The radiated parts occupied a total size of 26 × 25.6 × 3.57 mm3. It designed to operate at UMTS, m-WiMAX and 5 GHz WLAN bands. Simulated and measured results are in good agreements.