TX2EH-433-64-5V RADIOMETRIX [Radiometrix Ltd], TX2EH-433-64-5V Datasheet - Page 4

• Manufacturer Part Number: TX2EH-433-64-5V
• Description: UHF High Power FM Transmitter
• Manufacturer: RADIOMETRIX [Radiometrix Ltd]

Antenna requirements
Three types of integral antenna are recommended and approved for use with the module:
A) Helical
B) Loop
C) Whip
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.
[e-mail]
B. Loop antenna
C. Whip antenna
A. Helical antenna
Ultimate performance
Easy of design set-up
Size
Immunity proximity effects
Wire coil, connected directly to pin 2, open circuit at other end. This
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.
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.
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
16.4cm
C3
C4
C2
RF
RF
C1
RF-GND
RF
Fig.8: Antenna
TX2H – Data
0.5 mm enameled copper wire
close wound on 3.2 mm diameter former
433 MHz = 24 turns
wire, rod, PCB-track or a combination
of these three
433 MHz = 16.4 cm total from RF pin.
Feed point 15% to 25% of total loop length
track width = 1mm
4 to 10 cm inside area
helical
**
**
***
**
2
A
*
*
**
***
loop
B
***
***
*
*
whip
C
antenna
Page - 4 -
is
very