There are several advantages of using a trace antenna in your RF product design. Among them include good performance, low cost, and small size for frequencies over 900MHz. You might want to keep in mind the following tips on making your antenna design flawless.
Available Antenna Types
Widely available standard designs you can use are F-type, L-type, and monopole. The standard F-type antennas are most commonly used and they offer the best trade-off between efficiency and size.
Circuit Board Constructions
Antennas require a keep-out area on the PCB, which is located around the antenna trace. Take note that the length of the PCB will determine the resonant frequency in which the trace will be shorter when the frequency is high.
Ground Plane Is Critical
PCB trace antennas are dependent on the ground plane. Thus, they can be effective if they have a ground plane. The impedance and performance of the PCB antenna will be affected by the shape and size of the ground plane that is relative to the antenna.
The total RF link budget and range performance will be greatly reduced when there is a mismatched antenna. So, make sure to incorporate a pi-network placed directly to the antenna feed point. This will prevent any unnecessary mismatch losses.
Beware Of The Environment
Take note that in antenna design, there are factors that can affect the turning and radiation pattern of the antenna. Such would include metal components, plastic enclosures, and the presence of components near the antenna itself. Therefore, don’t put any metallic objects or use a metalized or metallic plastic enclosure. All external influences that can affect the effectiveness of the antenna should be put far away on the field.
Every Application Needs Tuning
The PCB antenna is dependent on its board and its dimensions and matching are important for its implementation.
If you tend to copy an existing antenna design, you might not be able to ensure good performance. There are variations in grain and radiation when the parameters in the surroundings change.
So the length of the antenna design needs to be adjusted in conformance to these variables. Moreover, you need to complete the final tuning and matching in the end product enclosure and installation and not in the open air.
Importance Of Antenna Matching
When the antenna impedance will match the source impedance of 50 ohms, there is a transfer of maximum RF power.
For instance, you may consider a return loss of less than -10dB to be a good antenna match. This only means that 10% of the incident power has been reflected because of mismatch.
The return loss of the antenna has been characterized by measuring the reflected power at the feed point of the antenna, including its matching components.
The antenna then is disconnected from the transceiver, then a network analyzer is connected through a coaxial cable to the antenna in order to perform the measurements.
Take note that it is good to tune the antenna when it is in proper position and environment during normal operation.
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