TXM-418-RM Linx Technologies Inc, TXM-418-RM Datasheet - Page 8

• Manufacturer Part Number: TXM-418-RM
• Description: TRANSMITTER RF 418MHZ
• Manufacturer: Linx Technologies Inc
• Series: RMr

Specifications of TXM-418-RM

• Frequency: 418MHz
• Applications: ISM, Remote Monitoring, Telemetry
• Modulation Or Protocol: ASK, OOK
• Data Rate - Maximum: 10 kbps
• Power - Output: -4dBm ~ 4dBm
• Current - Transmitting: 6mA
• Data Interface: PCB, Through Hole
• Antenna Connector: Through Hole
• Voltage - Supply: 5.9 V ~ 9 V
• Operating Temperature: -10°C ~ 55°C
• Package / Case: SIP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -
• Memory Size: -
• Other names: TXM-418-RM-R

ANTENNA CONSIDERAT I O N S
Page 8
Antenna Selection Chart
PA R A M E T E R
Ultimate perfo r m a n c e
Ease of design setup
S i ze
I m munity to proximity effe c t s
The range of the RF link is widely va ri a ble and depends upon the type of antenna employe d
and the operating env i r o n m e n t . Proper design and matching of an antenna is a complex
task requiring sophisticated test equipment and a strong back ground in principles of RF
p r o p a g a t i o n . While adequate antenna perfo rmance can often be obtained by trial and error
m e t h o d s, you may also want to consider utilizing a premade antenna from Linx. Our low - c o s t
antenna line is designed to ensure maximum perfo rmance and Pa rt 15 compliance.
It is usually best to utilize a basic quart e r - wave whip for your initial concept eva l u a t i o n .T h i s
can easily be made from a piece of wire as shown on the next page. Once the prototype
product is operating satisfa c t o ri l y, a production antenna should be selected to meet the cost,
s i ze and cosmetic requirements of the product. It is important to recognize that the antenna
p l ays a significant role in determining the perfo rmance and legality of your end product. I n
order to gain a better understanding of the considerations invo l ved in the design and
selection of antennas, please rev i ew Linx applications note #00500 “ A n t e n n a s : D e s i g n ,
Application, Pe r fo rm a n c e ” .
The fo l l owing notes should help in ach i eving optimum antenna perfo r m a n c e :
1 .
antenna to detune. For this reason the antenna shaft and tip should be positioned as fa r
away from such objects as possibl e.
2 .
mounted at a right angle to the gr o u n d - p l a n e. In many cases this isn’t desira ble fo r
p ractical or ergonomic reasons; t h u s, an altern a t i ve antenna style such as a helical,
l o o p, patch, or base-loaded whip may be utilize d .
3 .
"Board Layout Considera t i o n s " . This allows your product's output power to be adjusted
for certification purposes without change or compromise to the antenna.
4 .
p a rt i c u l a rly large items like tra n s fo rm e r s, batteri e s, and PCB tra cks and gr o u n d - p l a n e s.
In many cases, the space around the antenna is as important as the antenna itself.
5 .
c o u n t e rp o i s e, fo rming, in essence, a 1/2-wave dipole. For this reason adequate gr o u n d -
plane area is essential. As a general rule the ground-plane to be used as counterp o i s e
should have a surface area
6 .
Switching power supplies, oscillators, even relays can also be significant sources of
potential interfe r e n c e. The single best weapon against such problems is attention to
placement and layo u t . Filter the module’s power supply with a high-frequency by p a s s
c a p a c i t o r. Place adequate ground-plane under all potential sources of noise. S h i e l d
noisy board areas whenever pra c t i c a l .
7 .
away from the main equipment. This avoids interference problems and allows the
antenna to be oriented for optimum RF perfo rm a n c e. A l ways use 50
RG-174 for the remote fe e d .
P r oximity to objects such as a user’s hand or body, or metal objects will cause an
O p t i mum perfo rmance will be obtained from a 1/4- or 1/2-wave straight whip
It is always a good practice to include a T- a t t e nuation pad as described under
If an internal antenna is to be used, keep it away from other metal components,
In many antenna designs, part i c u l a rly 1/4-wave whips, the ground-plane acts as a
R e m ove the antenna as far as possible from potential internal interference sources.
In some applications it is advantageous to place the transmitter and its antenna
= FAIR
the ove rall length of the 1/4-wave radiating element.
= G O O D
L O O P
= E X C E L L E N T
H E L I C A L
coax such as
W H I P