The 5 Basics of RF Design

Published on April 2, 2019

If it's time to go wireless, don't forget the basics of RF Design. You may be excited about your new wireless project: innovative design, environmentally friendly, consumer demand, and the list could go on. Whether your budget is substantial or minimal, it is important to keep in mind the following RF design questions in order for your project to go ahead without a hitch.

Where will your product be based?
How will your product be used?
How large is the production?
How will your product be powered?
What is your budget and time frame?

1. Where will your wireless product be based? U.S., Asia, Europe, Canada?

Knowing where the product will be sold will help you during the RF design and certification process. Different regulatory bodies control frequency spectrum, allowable output power, and testing requirements. For instance, in the US (per FCC regulations), you can operate a product in the 902-918 MHz ISM band, while in Europe (per ETSI regulations), the same band is not allowed, however the Short Range Device (SRD) band of 863 to 870 MHz is license free and may provide similar performance. The 2.4 GHz ISM band is the most widely used frequency as it is a license free band in more than 95% of the world. When designing your product, you must understand if you are designing per FCC rules (US), ETSI (Europe), C-Tick (Australia), or IC (Industry Canada).

2. Who will be using your wireless product and how will it be used?

Understanding how the RF product will be used will affect the type of radio selection and antenna design or selection. For instance, if it is a handheld product, you may want to consider a radio that does not operate in the 2.4 GHz band, for superior range performance, as the human body radially absorbs RF energy at 2.4 GHz. Additionally, you will want to optimize the antenna for use on the human body and consider if SAR (Specific Absorption Rate) or RF exposure testing is required.

3. How large is the production of your wireless product, and within what time frame is your product desired?

The FCC allows for modular approval which can be very advantageous to OEM's who are using the same RF design across multiple sku's or platforms. By meeting the FCC's 8 Key Requirements for Module Approval, you can certify the module once and reference the FCC ID number across all products. This can drastically save you time and money.

4. Does your wireless product need to be plugged-in, use solar power, or operate on batteries?

Understanding the power supply and operating conditions is critical when selecting a radio. Most popular radio technologies are relatively lower power, however there are significant differences between radios designed for ultra-low power sensor applications vs. radios designed for sending pictures or streaming videos.

5. What is your time frame and budget?

When it comes to RF design and development, you have multiple options on how to make your product wireless. Certified off-the-shelf rf modules are arguably the fastest and easiest way to market. Discrete design, another option, may provide you with the most aggressive product costs and optimized design for your application, however this type of implementation involves weeks to months of engineering efforts, plus certification costs and time.

Consult with an Expert to Avoid Hidden Dangers Along the Way

All these RF design factors have an impact on cost and risk. With a little due diligence up front, you can avoid many pitfalls along the way. Take time to make sure all interested parties are in agreement with the work ahead.

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Written by Jen Sarto

Jen is the Vice President of Sales at Ezurio (formerly Laird Connectivity). Prior to her work at Ezurio, Ms. Sarto worked for a manufacturer's representative in the New York Metro Area. Jen has a bachelor's degree in Engineering from Steven's Institute of Technology.