30 September 2019
A simple guide to impedance matching for RF
19 September 2016
When a brief lands on your desk, your role is to make sure your work matches the requirements of that specification as closely as possible. The success of your work is measured on your ability to meet that specification, whilst retaining a high-level of performance for the product you have designed.
Antenna are the eyes and ears of your products; their performance is fundamental to any wireless device. Here are 7 essential aspects to consider when designing antenna into your product designs:
The determining factor that decides what frequency products use are the features outlined in a brief. Frequencies need to match their source (e.g. an access point, amplifier, or router), so the wireless technologies required will be decided by the features the product requires.
As smart devices are everywhere, and the IoT continues to grow, more and more products will need to be connected to be commercially viable. As a result, 2.4GHz and 3G / LTE capable antenna will certainly become a feature of many of your future designs.
In the past, the frequency would dictate the size of the antenna, but as more attention is placed on advanced, innovative antenna, it’s now not necessarily a rule of thumb.
Placing antenna on your circuit board should be one of your very first considerations and decisions you take.
You cannot leave the decision to place your antenna until the last minute: you won’t have the freedom to position the antenna in the optimum location. You cannot simply ‘throw’ an antenna onto your circuit board, as it’s one of the few parts that could drastically affect the performance of a product.
Leaving this positioning and placement decision towards the end of your design process could result in missed deadlines as you scramble to redesign the integral aspects of any wireless device.
Isolation issues can negatively affect the performance of an antenna product, vastly underperforming in terms of the specification outlined.
These isolation issues occur from coupling effects, i.e. when both transmitting and receiving signals are interfering with one another, causing poor performance. Your objective should be to isolate these signals from each other.
Without isolating these two conflicting signals, products you design will become good at one or the other; a big-mouthed alligator, or a big-eared elephant.
Imagine your circuit board as a runway, and your antenna the hangar. The bigger the runway, the easier it is for planes to take off and land as they need to. This is the case when frequencies hit your circuit board, they rebound and mirror your antenna, reducing packet loss.
Therefore, the size of PCB you select will play a role in the performance of your antenna, affecting both efficiency and bandwidth. Using a circuit board that is similar in size to the reference board set out in the product specification will help ensure performance isn’t impaired.
Of course, when you assemble the parts together in your design, you must make consideration for the host ground plane size, but also the position of other parts to maximise the performance of the antenna.
Following best practice for performance, you should design products based on the evaluation board, and arrange parts so metallic or magnetically charged ones are sufficiently far away from the antenna. This is where your expertise as a product designer comes in, and knowing this information will ensure your designs deliver on performance.
Material selection is among the first considerations when designing a fit-for-purpose product, however, this material selection (and material of nearby parts) can also negatively affect the performance of your antenna.
Metallic objects, parts, or encasings can severely manipulate radiation patterns and the tuning of your antenna. Avoid using materials and parts that could possibly interfere with this signal, including magnetically charged materials. If deemed absolutely necessary, keep metal parts away from the antenna.
As the eyes and ears of a wireless device, more importance is now placed on the performance of an antenna. Considering the actual real-life applications of the product may help you make a better decision on the type of antenna and where you design it.
Asking questions about how consumers would use the product will enable you to design the antenna into the right position, and consider environmental factors that may influence performance.
When integrating antenna into your product design, these 7 considerations will decide the overall performance of wireless devices. Poor wireless performance can lead to many difficulties, and any oversights will become glaring issues in testing. In some cases, oversights in antenna design could lead you to a product redesign because of the antenna.
Antennas are not like digital components. A digital component will perform as per its specification. An antennae performance is greatly affected by the points above. So, because of this, it’s placement is critical to the wireless performance and so should be considered first in your overall design.