TXM-900-HP-II Linx Technologies Inc, TXM-900-HP-II Datasheet - Page 12

• Manufacturer Part Number: TXM-900-HP-II
• Description: TRANSMITTER RF 900MHZ 8-CHANNEL
• Manufacturer: Linx Technologies Inc
• Series: HP2r

Specifications of TXM-900-HP-II

• Frequency: 902MHz ~ 928MHz
• Applications: ISM, RKE, Security and Fire Alarms
• Modulation Or Protocol: FM, FSK
• Data Rate - Maximum: 50 kbps
• Power - Output: -3dBm ~ 4dBm
• Data Interface: PCB, Through Hole
• Antenna Connector: Through Hole
• Voltage - Supply: 2.17 V ~ 16 V
• Operating Temperature: 0°C ~ 70°C
• Package / Case: SIP
• Lead Free Status / RoHS Status: Contains lead / RoHS non-compliant
• Features: -
• Memory Size: -
• Current - Transmitting: -
• Other names: TXM-900-HP2; TXM-900-HP2

Page 12
ANTENNA CONSIDERATIONS
of the considerations involved in the design and selection of antennas please review
as far away from such objects as possible.
mounted at a right angle to the ground-plane. In many cases this isn’t desirable for
away from the main equipment. This avoids interference problems and allows the
The range of the RF link is widely variable and depends upon the type of antenna
employed and the operating environment. Proper design and matching of an
antenna is a complex task requiring sophisticated test equipment and a strong
background in principles of RF propagation. While adequate antenna performance
can often be obtained by trial and error methods, you may also want to consider
utilizing a premade antenna from Linx. Our low-cost antenna line is designed to
ensure maximum performance and Part 15 compliance.
It is usually best to utilize a basic quarter-wave whip for your initial concept
evaluation.This can easily be made from a piece of wire as shown on the next page.
Once the prototype product is operating satisfactorily, a production antenna should
be selected to meet the cost, size and cosmetic requirements of the product. It is
important to recognize that the antenna plays a significant role in determining the
performance and legality of your end product.In order to gain a better understanding
Linx applications note #00500 “Antennas: Design, Application, Performance”.
The following notes should help in achieving optimum antenna performance:
1.
an antenna to detune. For this reason the antenna shaft and tip should be positioned
2.
practical or ergonomic reasons;thus, an alternative antenna style such as a helical,
loop, patch, or base-loaded whip may be utilized.
3.
"Board Layout Considerations". 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.
a counterpoise, forming, in essence, a 1/2-wave dipole. For this reason adequate
ground-plane area is essential. As a general rule the ground-plane to be used as
counterpoise should have a surface area
radiating element.
6.
sources. Switching power supplies, oscillators, even relays can also be significant
sources of potential interference. The single best weapon against such problems is
attention to placement and layout. Filter the module’s power supply with a high-
frequency bypass capacitor. Place adequate ground-plane under all potential
sources of noise. Shield noisy board areas whenever practical.
7.
antenna to be oriented for optimum RF performance. Always use 50 coax such as
RG-174 for the remote feed.
Proximity to objects such as a user’s hand or body, or metal objects will cause
Optimum performance will be obtained from a 1/4- or 1/2-wave straight whip
It is always a good practice to include a T-attenuation pad as described under
If an internal antenna is to be used, keep it away from other metal components,
In many antenna designs, particularly 1/4-wave whips, the ground-plane acts as
Remove the antenna as far as possible from potential internal interference
In some applications it is advantageous to place the transmitter and its antenna
the overall length of the 1/4-wave