Design of Wideband Balanced Folded-Arms Dipole Antenna for Mobile Handsets

Abstract Investigations of a wideband balanced antenna for mobile handsets covering three bands—GSM1800, GSM1900, and UMTS—are presented. Balanced antennas have advantages in handset applications as they are less affected by juxtaposition with human tissue than unbalanced types. The antenna is a slotted planar dipole with its arms folded and not connected at their ends. The antenna is fed by a balanced voltage source. The antenna impedance was investigated using two different methods, including an S-parameter method and a mirror image method. For the purpose of antenna stability evaluation and power gain measurement, a wide bandwidth planar balun was adopted and modified to feed the antenna from an unbalanced source. For validation, prototypes of the antenna were fabricated and tested. The calculated and measured results in terms of return loss show good agreement and the results also show good wideband characteristics.

[1]  Young-Hoon Min,et al.  Compact low cost antenna for passive RFID transponder , 2006, 2006 IEEE Antennas and Propagation Society International Symposium.

[2]  X.-D. Wu,et al.  Coplanar waveguide fed coplanar strip dipole antenna , 1994 .

[3]  R. Meys,et al.  Measuring the impedance of balanced antennas by an S-parameter method , 1998 .

[4]  M.Y.W. Chia,et al.  A new wide-band planar balun on a single-layer PCB , 2005, IEEE Microwave and Wireless Components Letters.

[5]  K. Fujimoto,et al.  Wideband folded loop antenna for handsets , 2002, IEEE Antennas and Propagation Society International Symposium (IEEE Cat. No.02CH37313).

[6]  Max J. Ammann,et al.  Wideband monopole antennas for multi-band wireless systems , 2003 .

[7]  Yongho Kim,et al.  A folded loop antenna system for handsets , 2001, IEEE Antennas and Propagation Society International Symposium. 2001 Digest. Held in conjunction with: USNC/URSI National Radio Science Meeting (Cat. No.01CH37229).

[8]  Raed A. Abd-Alhameed,et al.  SAR and radiation performance of balanced and unbalanced mobile antennas using a hybrid computational electromagnetics formulation , 2004 .

[9]  Kin-Lu Wong,et al.  Ultrawide-band square planar metal-plate monopole antenna with a trident-shaped feeding strip , 2005, IEEE Transactions on Antennas and Propagation.

[10]  Kyohei Fujimoto,et al.  Performance of balance-fed antenna system for handsets in the vicinity of a human head or hand , 2002 .

[11]  Hisashi Morishita,et al.  Wideband and compact folded loop antenna , 2005 .

[12]  P.S. Excell,et al.  Bandwidth enhancement of balanced folded loop antenna design for mobile handsets using genetic algorithms , 2007, 2007 IEEE Antennas and Propagation Society International Symposium.

[13]  J. Legarda,et al.  Design of UWB folded-plate monopole antennas based on TLM , 2006, IEEE Transactions on Antennas and Propagation.

[14]  R. A. Abd-Alhameed.  SAR and radiation performance of balanced and unbalanced mobile antennas using a hybrid formulation , 2004 .