RX2G 데이터 시트보기 (PDF) - Radiometrix Ltd
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RX2G Datasheet PDF : 10 Pages
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Antenna requirements
Three types of integral antenna are recommended and approved for use with the module:
A. Helical antenna
0.5 mm enameled copper wire
close wound on 3.2 mm diameter former
RF
433 MHz = 24 turns
C2
C3 C4
B. Loop antenna
16.4cm
C. Whip antenna
Fig.6: Antenna configuration
RF-GND
C1
Feed point 15% to 25% of total loop length
track width = 1mm
4 to 10 cm2 inside area
RF
wire, rod, PCB-track or a combination
of these three
RF
433 MHz = 16.4 cm total from RF pin.
Features
Ultimate performance
Easy of design set-up
Size
Immunity proximity effects
Range open ground to similar antenna
(for TX2A-433-14-5V & RX2G-433-15-5V)
Antenna selection chart
A
helical
**
**
***
**
200m
B
loop
*
*
**
***
100m
C
whip
***
***
*
*
300m
A) Helical
Wire coil, connected directly to pin 2, open circuit at other end. This
antenna is very
efficient given it's small size (20mm x 4mm dia.). The helical is a high Q antenna, trim the wire
length or expand the coil for optimum results. The helical de-tunes badly with proximity to other
conductive objects.
B) Loop
A loop of PCB track tuned by a fixed or variable capacitor to ground at the 'hot' end and fed
from pin 2 at a point 20% from the ground end. Loops have high immunity to proximity de-
tuning.
C) Whip
This is a wire, rod, PCB track or combination connected directly to pin 2 of the module.
Optimum total length is 15.5cm (1/4 wave @ 433MHz). Keep the open circuit (hot) end well
away from metal components to prevent serious de-tuning. Whips are ground plane sensitive
and will benefit from internal 1/4 wave earthed radial(s) if the product is small and plastic cased
The antenna choice and position directly controls the system range. Keep it clear of other metal in the system,
particularly the 'hot' end. The best position by far, is sticking out the top of the product. This is often not
desirable for practical/ergonomic reasons thus a compromise may need to be reached. If an internal antenna
must be used try to keep it away from other metal components, particularly large ones like transformers,
batteries and PCB tracks/earth plane. The space around the antenna is as important as the antenna itself
Radiometrix Ltd, TX2A/RX2G Data Sheet
page 8
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