Pain Points for RF Product Design

Mastering RF Product Design: Overcoming Challenges for High-Performing Wireless Systems

RF product design is one of the most challenging aspects of product development, often described as a ‘black art’ that blends engineering and science. From active wireless technologies like Bluetooth and Wi-Fi to passive RFID tagging, RF challenges span across industries and applications. Without expert guidance early in the design process, these challenges can lead to costly delays and regulatory roadblocks.

What You'll Learn

• The top RF design challenges and how to navigate them.
• Best practices for PCB design, 5G implementation, and regulatory compliance.
• Tips for overcoming the RF talent gap and why experienced engineers are essential.

Having been involved in developing products across virtually every category—from consumer to medical to commercial to DoD/aerospace—we’ve found that wireless technology consistently introduces complex RF system design challenges. These problems demand a high level of expertise rooted in physics to develop effective solutions.

The range of RF design problems includes active wireless communication technologies (e.g., satellite, cellular, Wi-Fi, and Bluetooth) and passive RFID tagging, such as NFC payment systems or retail item tracking. Additionally, RF system design must address UL- and FCC-related issues, robust circuit design, and effective PCB layout to minimize unintentional emissions and external interference. These considerations apply to almost any product with a wire that conducts power.

Below are five of the most unique RF challenges in technology product development:

1. Issues Related to PCB Design

PCB design, especially for high-density and mixed-signal boards, presents significant challenges in RF system design. While larger, lower-density boards may use off-the-shelf or reference antenna designs, compact circuits often require custom antenna solutions.

Antenna configuration and placement play a critical role in radio performance, especially in handheld and mobile products. However, space constraints often limit antenna size, making it challenging to maintain efficiency. For example:

• Chip antennas may be required for compact designs but often struggle with reduced communication range.
• Monopole antennas, such as quarter-wave whip antennas, depend on PCB ground planes for counterpoise, adding another layer of complexity.

For high-density systems, off-the-shelf solutions like system-on-chip modules are helpful but come with layout and size trade-offs.

2. Multiple Radio Systems

The more radios in the system, the more antennas required, and the more intricate the antenna design becomes. This increases challenges in board layout and introduces potential crosstalk and interference issues. For example:

• Close placement of antennas can create interference between cellular and Wi-Fi signals.
• Proper antenna placement, orientation, and filtering techniques are critical to avoid degraded performance.

3. 5G System Design

Everyone is jumping on the 5G bandwagon, and for good reason. 5G builds upon 4G technologies and frequency bands while introducing new frequency ranges (25 to 40 GHz) for super high-speed communication applications. However, these high frequencies bring unique design and application challenges.

Due to the high frequency, performance is impacted by reduced range, as higher frequencies don’t penetrate physical environments as well as lower ones. This presents a tradeoff between range, bandwidth, and transmission rates. For instance:

• Ensuring super-high-speed data rates at these frequencies requires high base-station density and line-of-sight communication, increasing infrastructure costs.

4. System Design and Regulatory Issues

RF designers are not only responsible for radio integration but also for debugging regulatory compliance issues. Virtually every product with a wire faces challenges in meeting radiated and conducted emissions and susceptibility standards.

For example, systems that pass internal lab tests often encounter noise problems during agency approval due to variables like cable layout. To avoid costly redesigns and delays, RF engineers must:

• Design robust guard bands to handle emissions and susceptibility.
• Optimize PCB design, layout, and shielding. This includes ensuring sufficient capacitance, proper power/ground plane layout, and good signal trace routing.
• Address spurious emission failures caused by cables carrying common-mode currents through careful placement, filtering, and shielding techniques.

5. Finding the Talent

Skilled RF engineers are essential but difficult to find. They need a strong foundation in electrical engineering and physics, making the competition for experienced talent fierce. Additionally, the pipeline for RF-focused engineers remains small, with limited graduates specializing in this domain.

Almost any company developing electronic systems needs access to an RF expert, whether as a team member or a consultant. RF expertise is particularly critical for products undergoing UL and FCC testing, as few systems pass without requiring design adjustments. In RF engineering, understanding the physics of the problem is non-negotiable.

Conclusion

Navigating RF product design challenges requires expertise, foresight, and an understanding of the physics behind the problem. At IPS, our team of RF engineers is here to help you design high-performing, compliant products that meet your time-to-market goals.

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