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M2M Connectivity Blog

Guide to Choosing the Right Antenna

By 30/11/2017October 18th, 2021No Comments
Radiocrafts recently published a white paper guide to choosing the right antenna for your requirements. What follows is a summary of the key points from that paper:
Always keep the purpose and outcome of your project in mind while working on product and accessory design. It is easy to get carried away by the promise of what technologies can achieve, but what is the point of adding additional costs if the final results don’t meet the outcome? Or if the antenna appears as an afterthought to a self-contained piece of hardware.

Specifications to Consider
  • Size – What kind of device is the antenna attaching to? How can you make the most efficient use of space?
  • Operating frequency – Check your local frequency broadcast regulations and whether they will affect your project.
  • Performance/range – Will you require maximum range for your application? Will you require an omnidirectional solution?
  • Cost – How complex will the assembly of your antenna system be? Don’t let pricing concerns cloud your decision-making process.
  • Ease of use/knowledge/risk – If you are trying to increase your speed to market, you can’t afford to gamble on an antenna that may be complex to use, as it may result in design errors and ultimately, detuning or other problems.
  • Certification reuse – RF modules will usually have certifications which advocate the use of particular antenna types.
Antenna Types
  • Wire Antenna – A conductive wire soldered to the RF signal trace. It can be flexible or rigid, insulated or bare, and straight, bent or helical, depending on your requirements. Cheap to purchase, but manufacturing costs can be higher.
  • Whip Antenna – At its core it is a wire antenna, (usually formed as helical) which has been extended with a connector and moulded in plastic. The benefit is that it is usually shorter in length than a monopole, and can be bought off-the-shelf.
  • PCB Antenna – Printed Circuit Board (PCB) antennas are usually the lowest-cost option, as costs only come from the manufacture of the board itself. Available shapes include quarter wave monopole, inverted F antenna (PIFA) and meander.
  • Chip Antenna – One of the smaller, higher-performing antenna types.

Additional variations include stamped metal, ceramic patch, flat patch dipole, moulded helical, PCB-based with cable, and dome with cable.

Antenna Positioning & Matching

Correct positioning can be the key component to success or failure. Although requirements will vary with product selection, here are some guidelines that may assist:

  • When using reference designs, check clearance requirements
  • Try to leave as much space as possible around an antenna, especially the outer tip
  • “Matching” the antenna refers to the process of adjusting any impedance to the antenna, in order to maximise the power feed to the antenna while minimising reflection loss.
  • Matching may need to be tuned or designed if alterations have been made to a reference design, or if you are designing from scratch.

We hope some of these tips will assist you with your project, and if you are looking for hardware, advice, or an end-to-end solution, please reach out to our team via the button below.

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