SI4785 데이터 시트보기 (PDF) - Silicon Laboratories
부품명
상세내역
제조사
SI4785 Datasheet PDF : 69 Pages
| |||
AN383
5. Embedded Antenna for FM Transmit on TXO and Receive on LPI (Si4704/
05/06/1x/2x Only)
The FM Transmitter component on the Si471x/2x and the FM Receiver component on the Si4704/05/06/2x support
an embedded antenna interface through the TXO/LPI pin. In the case of the Si472x FM Transceiver, the same
embedded antenna can be used for both FM Transmit and Receive.
5.1. Embedded Antenna Design
An embedded antenna can be designed using a loose wire, flex circuit, or PCB trace and can be categorized into
two types: stub antenna and loop antenna. For the purpose of this application note, three types of embedded
antenna will be covered in detail:
Embedded stub (wire)
Embedded loop (wire)
Embedded stub (PCB trace)
The following table summarizes the advantages and disadvantages of these implementations.
Antenna
Embedded Stub (Wire)
Embedded Loop (Wire)
Embedded Stub (PCB
Trace)
Description
Wire attached to or
molded inside product
case
Connect to pin 4 for TX/
RX
Wire loop attached to or
molded inside product
case
Connect to pin 4 for TX/
RX
Wire trace fabricated on
outer PCB copper layer
Connect to pin 4 for TX/
RX
Advantages
Placement flexibility
Minimum PCB space
Easy to adjust length
during design testing
Can achieve high
efficiency per length
Placement flexibility
Minimum PCB space
Easy to adjust length
during design testing
No mechanical
attachment to case
Ease of product
assembly
Disadvantages
Mechanical attachment
to case required
Performance can be
impacted by case
shielding
Mechanical attachment
to case required
Performance can be
impacted by case
shielding
PCB keep out regions
required around
antenna
Additional PCB space
Performance can be
impacted by case
shielding
Figure 12 is an example of a stub antenna in wire implementation buried inside a cellular handset. Explanations of
the dimensions A, B, C, and D are included later in this document.
Rev. 0.8
25
Share Link: 