Hyengcheul Choi

Excitation techniques of loop current mode of ground antenna

Excitation techniques of the antenna, which induce loop current mode on the ground plane, are described in this paper. The antenna element is a small rectangular ground clearance connected by a capacitor. It can be excited by a direct feeding, shunt-driven, or resonated loop feeding, and each feeding method gives a different impedance bandwidth of the antenna at the 2.4 GHz frequency band.

Chip Antenna Using Three Branch Structures and Interdigitated Gap Feeding

This paper proposes chip antenna using three branch structures and interdigitated gap feeding method. Three branches consist of the spiral, straight monopole, and meander structure. Antenna has a compact size of 20 x 8 x 3.2 mm . Its size is minimized so that it can be easily installed to mobile handset. FR-4 (relative permittivity = 4.4) substrate is used in this chip antenna. In this paper, interdigitated gap feeding technique is proposed. By the adoption of this structure, the proposed antenna can be alleviated a reduction of bandwidth as well as easily controlled a resonant frequency. This antenna is designed to operate at penta band, GSM900/GPS/PCS/WCDMA/Bluetooth. VSWR and radiation patterns are measured by using a network analyzer and a anechoic chamber respectively.

Controlling Resonances for a Multi-Wideband Antenna by Inserting Reactive Components

A novel method is proposed to control the resonance frequencies of an antenna for multi-wideband operation. The parallel addition of reactive components to an antenna shifts the resonance frequencies without increasing the size of the antenna. These resonance frequency shifts can be analyzed by observing the voltage difference via an approach based on an open-circuit transmission line. The designed antenna has 180 MHz (940-1120 MHz) and 630 MHz (1970-2600 MHz) bandwidths under VSWR=2.5:1 with a high radiation efficiency at dual-band. The lower and the higher bands of the antenna provide coverage for Global System for Mobile communications 900 (GSM900), Universal Mobile Telecommunications System 2100 (UMTS2100), Wireless Broadband (WiBro) and Bluetooth.

Ground antenna for GPS using lumped elements

A compact and low-profile antenna for the global positioning system application is presented, based on two capacitors and one inductor. Since the system ground plane is fully utilized as a radiating structure in this antenna, the antenna size can be miniaturized while radiation efficiency keeps high. This ground antenna occupies 15 × 5 mm2 on the ground plane and has a bandwidth of 45 MHz (1540–1585 MHz) for the voltage standing wave ratio < 3. In this work, we further illustrate the operation of the ground antenna by using the electromagnetic coupling concept.

SAR reduction of smart watch antenna using meander loop structure

A meander loop type antenna is proposed for reducing SAR values. SAR test is conducted on the wrist and mouth scene. The measured SAR of the meander loop antenna is compared with that of the monopole antenna and the loop antenna. Because the middle point of the meander loop antenna is located toward watch body and away from a human wrist, SAR and TRP of that can be improved.

A Small Antenna of High Radiation Efficiency Employing a Ground Radiator

This paper introduces the method to utilize a terminal ground as a radiator only using reactive components without an antenna structure. Characteristics of the proposed antenna is compared with that of the meander IFA on the same ground plane() for the bluetooth band. From simulation and measurement data, it is found that the proposed antenna using only capacitors provides the highest radiation efficiency. This is because of that the higher inductance reduces radiation resistance of a ground and the capacitor has a lower loss resistance comparing to that of the IFA or the inductor. In spite of the high radiation efficiency, the area () of the proposed antenna is less than half of the area () of the IFA.

Design of gap-fed antenna adjacent to ground of a mobile handset

In this paper, an antenna for mobile handsets is considered as a lossy transmission line to study the effect of distance between an antennas and ground. From this model, it is shown that a characteristic impedance of an antenna affects the input impedance. This paper proposes a gap-fed monopole antenna to reduce the proximity effect of a ground plane.

Ferrite sheet loaded PIFA for critical couping

A method which can achieve the critical coupling of PIFA is proposed. It is accomplished by only attaching the ferrite sheet without changing the structure of the antenna. It is modeled by equivalent circuit based on transmission line modeling and the critical coupling can be confirmed by Smith chart of the antenna. The proposed antenna is verified by 3D EM simulator. The ferrite sheet loaded PIFA can easily attain to critical coupling and it has sufficient bandwidth, 880-1040 MHz (VSWR<2).

A Design of Miniaturized Built-in Penta-Band Chip Antenna for Mobile Handset

The novel internal monopole chip antenna of penta-band operation for GSM850/GSM900/DCS/USPCS/WCDMA bands for mobile phones is proposed. This antenna occupies a small volume and is suitable to be embedded in a mobile phone as an internal antenna. The minimization of the proposed antenna was realized by using spiral line structure and meander line structure on FR-4 of dielectric

Realization of Gain Improvement Using Helix-Monopole Antenna for Two-Way Portable Radio

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