FLAP ANTENNA ON THE LABEL
Original Publication Date: 1995-Mar-01
Included in the Prior Art Database: 2002-Mar-21
Mohamad F. Yahaya: AUTHOR [+2]
The demand for low power personal communi- cation systems (PCS) such as DECT, PPS2000, JHP is increasing at a large rate. The area of coverage is one of the most important figures of merit in these systems. The antennas have to perform very well in order to compensate for the low power.
MO-LA Technical Developments Volume 24 March 1995
FLAP ANTENNA ON THE LABEL
by Mohamad F. Yahaya, Argyrios A. Chatzipetros and Rudy Yorio
by the antennas is approximately equal, 2) The cor- relation of these signals is small (typically less than
The most effective single antenna structure used in a portable is a whip antenna which normally is a half-wavelength radiator. For a diversity handheld, the choice oflocation and polarization ofthe second antenna is very critical and has a significant impact on performance.
Two possible schemes are: (a) Diversity antenna in the flap (requires coax), and (b) Planar antenna on the bottom surface ofthe housing coupled to the flap antenna (no coax required).
Case (a) is shown in Figure 1. The two antennas are combined through a switch. The second antenna is located in the flap and consists of two parts: the transmission line section and the radiating section. The antenna is connected to the switch via a coax- ial transmission line passingg through the hinge. The polarization of this antenna is opposite to the one ofthe whip.
A very effective diversity scheme is achieved here because the antenna configuration provides both space and polarization diversity. In addition to this, the performance of the antenna in the flap is good in the talking position because the radiating section of the antenna is as far away from the user's head as possible. It is expected here that the performance of the second antenna will be comparable to that of the whip.
Case (b) is shown in Figure 2. The second antenna consists of two parts: the feed which is located at the bottom section of the portable and the parasitic (a half-wavelength resonator) located in the flap. The feed is a quarter wave structure transforming a low impedance point to a high imped- ance point. It is connected to the RF circuitry with a transmission line such as coaxial cable, microstrip,
0 Motorola, 1°C. 19%
The demand for low power personal communi-
cation systems (PCS) such as DECT, PPS2000, JHP is increasing at a large rate. The area of coverage is one of the most important figures of merit in these systems. The antennas have to perform very well in order to compensate for the low power.
One important way to improve communications and increase the area of coverage is diversity. The benefits of diversity applied to communication sys- tems are well established. It is a well known method for reducing the effects offading.
2.0 THE PCS ENVIRONMENT
In a typical PCS environment, multipath inter- ference is created by multiple reflections ofthe trans- mitted signal from several structures. The resultant received waveform is a sum oftime and, sometimes, frequency shifted versions of the original transmis- sion, and, depending on the chan...