Tel: 886-2-66296288

Fax: 886-2-29174598

URL: http://www.princeton.com.tw

PT4316 V1.6

- 13 -

August, 2007

Low Power 315/433 MHz OOK/ASK Superheterodyne

Receiver with SAW-based Oscillator

PT4316

ANTENNA DESIGN

For a λ/4 dipole antenna and operating frequency,

f (in MHz), the required antenna length, L (in cm),

may be calculated by using the formula

f

L

7132

=

.

For example, if the frequency is 315MHz, then the length of a λ/4 antenna is 22.6cm. If the calculated

antenna length is too long for the application, then it may be reduced to λ/8, λ/16, etc. without

degrading the input return loss. However, the RF input matching circuit may need to be re-optimized.

Note that in general, the shorter the antenna, the worse the receiver sensitivity and the shorter the

detection distance. Usually, when designing a λ/4 dipole antenna, it is better to use a single

If the antenna is printed on the PCB, ensure there is neither any component nor ground plane

the length of the antenna,

L (in cm), is calculated by

r

f

c

L

ε

×

×

=

4

where “c” is the speed of light (3 x 1010 cm/s)

When the PT4316 is operated in a noisy environment, it is recommended that an external SAW filter be

added between the input matching network and antenna.