OPERATION GUIDE
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OG_CDP-02F-R_v30e
Circuit Design, Inc.
12
ANTENNAS
The most important factors for safe data transmission are a good antenna and RF grounding, both for the
transmitter and the receiver. Without an antenna it is impossible to transmit data over a long distance.
The standard antenna is a Lambda/4 wire protected by a plastic cover.
The receiver has a simple antenna input pin. Any suitable UHF antenna can be connected to it.
The easiest way to connect an antenna to the CDP-RX-02F-R is to solder a 17 cm wire directly to the antenna
input. A 50 Ohm coaxial cable can be used to extend the distance between the antenna and the receiver. The
shielding of the antenna wire should be soldered to the case near the antenna input of the CDP-RX-02F-R.
It is possible, but not recommended to connect the receiver module and the antenna by a connection on the
PCB. This will decrease the receiver performance in most cases.
To find the best method of installation for the transmitter and receiver, many things should be considered and
tested. It is recommended that you read specialized literature on antennas and radiation characteristics to gain
a better understanding of these fields. A detailed explanation cannot be given here.
Notice: For CDP-TX-02F-R and CDP-TX-02FP-R, use the antenna provided. Using other antennas may
invalidate compliance with the regulatory standards. Refer to the REGULATORY COMPLIANCE
INFORMATION in this document.
In most cases the following basic rules will help you.
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Connect an antenna with 50 Ohm impedance for 434 MHz.
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The easiest construction is a wire of approximately 17 cm.
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Place the antenna vertically, straight up or down from the transmitter and receiver module.
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Do not cover the antenna with metal parts.
•
The connection of the metal surface of the transmitter and receiver case to a larger metal part (ground
plane) will increase radiation and reception efficiency. These metal parts should not be placed near the
antenna.
•
The best range is achieved if the transmitter and receiver antenna are in direct line of sight. Any object in
between the transmitter and receiver antenna, and metallic objects in particular, will decrease the range.
•
The transmission is influenced by reflections of the transmitter signal on metallic surfaces. By overlaying
the direct and reflected signal with a 180 degree phase shift the signal can almost fade out. These
reflections and fade-outs can result in data drop-outs in mobile applications.
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The human body can have a similar effect as metal objects. Pocket transmitters should be held in your
hand, held in a position away from the body and pointed in the direction of the receiver.
