Browse Prior Art Database

Built-in Antenna Over Plastic

IP.com Disclosure Number: IPCOM000004608D
Original Publication Date: 2001-Feb-28
Included in the Prior Art Database: 2001-Feb-28
Document File: 1 page(s) / 53K

Publishing Venue

Motorola

Related People

Son Quang Le: AUTHOR

Abstract

Built-in Antenna Over Plastic

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Built-in Antenna

Over Plastic

By

Son Quang Le

More products are becoming smaller and smaller in size and volume and it is becoming more of a challenge for engineers to fit in all mechanical and electrical features. Therefore we must be creative with conceptions to accommodate the space.

We recently received some comments from customers that their pagers are having difficulties with reception in high density areas (downtown with tall buildings) and low elevation locations.

Most pagers are designed with an internal antenna which provide minimal RF performance. The length of the antenna traces are very important to the performance of the antenna. That is why an external antenna is preferred over the internal. To design an internal antenna, we must take into consideration a few major challenges: spacing stack up availability in XYZ directions, location constraints and PCB layout limitations. Good antenna designs require proper distance from local components. The maximum length of the antenna tracing is very critical, and must have a good isolation area that keeps away from any metal obstruction in 3 planes. A "chip" surface mounted antenna is one type enjoying current use. It is an "H" field antenna. It is very compact and fits easily in a tight stack up, but it produces a marginal performance because of it size.

RF engineers have done an extensive study on a new antenna called "micro strip" antenna. It is an "E" field antenna, using a small strip of G4 PCB material (.35x1.3 inches) with sufficient length of antenna's tracing edged to the PCB. They have discovered that the transmitting and receiving is improved 3-5x when compared with the chip antenna.

We will apply a similar principle to any current or future pagers or cellphone device. This can be done by edging the antenna tracing to the plastic (housing, battery door) and using a set of pogo pins, flex, or the like to make connections between the tracing to the RF PCB. It can be edged into the battery door, using copper acid edge process into high class filled polycarbonate material or Ultum-like material. This will eliminate any additional mechanical piece parts. This will save space and the antenna now will be positioned close to the outside of the unit.