Shogo Hayashida

Built-in folded dipole antenna for handsets

One of the trends observed in mobile telephone technologies is the reduction in the size and weight of the handset. Accordingly, antennas used for such handsets must also follow the downsizing of the handset unit. Especially, built-in antennas are required for the latest handset antenna designs. A built-in folded dipole antenna (BFDA) for a handset is introduced and analyzed. The structure of the BFDA gives it a low profile. In the analysis, the electromagnetic simulator IE3D based on the method of moments (MoM) is applied to calculate antenna characteristics such as VSWR, current distribution and radiation patterns. The antenna has a self-balanced effect and a bandwidth of about 13%.

Characteristics of Built-In Folded Monopole Antenna for Handsets

A folded loop antenna for handsets has already been introduced and shown as one of balance-fed antennas for handsets, which is very effective to mitigate the antenna performance degradation due to the body effect. In order to meet the requirements for the latest handsets such as low profile and small size, a folded loop antenna is modified. The antenna, which is possibly built in the handsets, is newly proposed. Low profile and small size is achieved by consisting of the half of low profile folded loop antenna, which has a structure folded loop elements sideways so that the antenna can be placed on the ground plane (GP). In the analysis, the electro-magnetic simulator based on the FDTD (Finite Difference Time Domain) method is used and the design parameters useful in practical operation are found. The electromagnetic simulator based on the Method of Moment (MoM) is used to calculate the current distribution on the antenna element and the GP. An example of low profile and small size antenna which has wideband characteristics are designed based on these parameters, and the antenna characteristics such as VSWR, the current distributions and the radiation patterns are compared with Planar Inverted-F Antenna (PIFA), which is one of conventional built-in antennas for handset. As a result, it has been confirmed that the physical volume of the antenna, which has been introduced here, becomes smaller than that of PIFA. In addition, the radiation efficiency of these antennas is measured and the results are compared with each other.

A planar folded dipole antenna for handset

In this paper, we propose a planar folded dipole antenna (PFDA). The PFDA consists of a folded loop element placed horizontally on the top of the ground plane (GP) so that the antenna has a lower profile. In the analysis, an electromagnetic simulator based on the model of moments is used. The design parameters, which are useful in practical operation, are obtained. An example of a low profile antenna is designed, based on these parameters, and antenna characteristics such as VSWR, the current distributions and the radiation patterns are shown. Furthermore, we study the miniaturization of the antenna including a GP by reducing the GP length.

Built-in half size of folded dipole antenna for handsets

In conventional handset antennas, some gain degradation is often observed when the handsets is hold at a talk position. This is caused by the variation of the current on the conducting box used in the handset due to the human body effect. By using a balance-fed antenna, the current can be reduced remarkably. Previously, a folded loop antenna (FLA) was introduced and analyzed as a balance-fed antenna element (Morishita, H. et al., Proc.IEEE AP-S, vol.3, p.440-3, 2001). The trend in handsets is to reduce their size and the weight. Antennas must also be downsized while keeping performance unchanged or improved, especially as built-in antennas are desired. In order to make the FLA lower and smaller in volume, a built-in half-size folded dipole antenna (BHFDA), is considered and analyzed. The BHFDA is half the size of a standard folded dipole antenna. The bandwidth is evaluated to be approximately 16%, even though the antenna is miniaturized.

Wideband Folded Loop and Folded Dipole Antennas

In this paper, the aim is to investigate the folded loop antenna (FLA) without ground plane (GP) in detail, and to find optimum antenna parameters for wideband characteristics. In the analysis, the electromagnetic simulator IE3D based on the method of moment (MoM) is used. Consequently, it is shown that the folded construction at both ends of the FLA is not necessary for wideband properties, and planar folded dipole antenna (FDA) also has wideband characteristics

A study on miniaturization of folded monopole antenna for handsets using a reactance slit

The latest trends in mobile phone handset units is to reduce their size and weight. Antennas used for such handsets must also follow the handset downsizing and yet keep the antenna performance unchanged or even improved. Furthermore, built-in antennas are becoming a more intense requirement for handsets. In order to make a low profile and small size, the built-in folded monopole antenna (BFMA) has been introduced. In order to confirm the basic antenna characteristics of BFMA, an FMA with a slit has been analyzed on the infinite ground plane (GP). The infinite GP has been used so that the analysis of the antenna does not depend on the size of the GP. In addition, the VSWR characteristics of the FMA with a slit have been compared with those of the BFMA and the PIFA. It has been confirmed that the folded part of the BFMA has a reactance loading effect like the slit of the FMA, and the FMA with a slit is miniaturized up to approximately 37% of the PIFA.