Antennas are key components of every wireless device. Without them, wireless electronics wouldn’t be able to communicate. Many consumers are completely unaware that their laptops, smartphones, wearables, and other everyday electronics have internal antennas embedded into their devices. In comparison, ideal antenna selection is an imperative design consideration for electrical engineers and developers. Luckily, Connected Development has the knowledge, experience, and testing facilities required to assist developers in finding a successful antenna match for their designs.
Internal vs External Antennas
The main difference between internal and external antennas is their location. Internal antennas are located inside a device, whereas external antennas are affixed to the outside of a device. While there are no major differences between the transmission power between internal and external antennas, there are technical differences in the coverage offered by each. For example, external Wi-Fi antennas provide coverage in a doughnut shape. In a smart home device, this can be a disadvantage in devices that need to transmit equivalent signal strength to areas above the antenna. While internal planar inverted F antennas (PIFA) provide more spherical coverage and are generally smaller in size than their external counterparts, their disadvantages lay in design complications. The PIFA construction is one of several different types of antennas that can be used internally, and each will have its own particular characteristics. A common misconception is that an internal antenna can be installed wherever there is a convenient place and adequate space for it.
The internal types have specific requirements for optimum operation, and any deviations from those specifications most often result in compromised performance. They are typically more susceptible to degradation from proximity to components or metallic surfaces than external types. Internal antennas must be carefully integrated into the design in order to minimize these negative interactions and maximize effectiveness.
Manufacturers’ data sheets provide information about how their components operate under optimum conditions, the likes of which are rarely seen in customers’ devices. Care must be taken when comparing the numbers in the data sheets to actual applications. Some vendors supply data of their components in more true-to-life applications than simply the ideal test board, and this can be valuable in estimating actual results.
While internal antennas are often chosen for their greater aesthetic appeal and are far less prone to physical damage, there are definite trade-offs to be considered. Maximum effectiveness becomes especially important if devices are used in licensed modes of operation such as LTE – specific criteria must be met in order to achieve carrier compliance.
When properly integrated and implemented, these internal antennas can perform quite well.
Internal antennas are used in wireless devices like:
· Computers & laptops
· Smart home technologies
External antennas are used in wireless devices like:
· Remote Sensors
Connected Development’s Comprehensive Pre-Compliance Antenna Testing Services:
Founded in 2009, Connected Development are experts in wireless and IoT devices. Equipped with their own anechoic chamber, Connected Development is one of few design houses that offers in-house pre-compliance testing (Figure 1). Developers can feel confident in their device’s certification success as pre-testing provides a means of knowing if official lab test results are representative of a product. Pre-compliance data allows test results and methods to be reviewed for errors before wasting time, energy, and resources caused by costly redesigns.
Figure 1: Antenna testing pattern
Connected Development offers a Fixed Price Pre-Compliance Testing Service option and provides full transparency of costs prior to utilizing their pre-testing services. Developers will benefit from reduced time to market as Connected Development’s skilled team of engineers can assist developers in ensuring proper antenna selection and function. Connected Development offers the following types of antenna pre-compliance test & measurement services:
· RF/Antenna performance testing
· Passive antenna pattern testing:
· Antenna design, matching, or tuning
· Performance of antennas throughout the design phase
· Verification of an un-licensed spectrum certified modules’ antenna gain limits set by the module vendor or the FCC limits for the radio type and service.
· PCB trace antenna gain and efficiency measurements
· PTCRB/CTIA OTA pre-testing:
· TRP and TIS
· Custom automated test campaigns
· Other performance or quality testing:
· Un-intentional radiated measurement testing
· RSE testing for harmonics of the transmitter using the same chamber and automation
· Pre-testing for CE Immunity tests
In collaboration with a Symmetry Electronics customer, Connected Development was able to successfully conduct Voltage Standing Wave Ratio (VSWR) testing for a commercial lighting product in their lab. Connected Development was able to measure the device’s Zigbee antenna in two positions: one with the Network Analyzer port connected directly to the coaxial cable of the antenna and the other with a coaxial pigtail soldered onto the PCB. Additionally, the customer benefitted from Connected Development’s strong network of connections as the device proved to be too large for passive test measurement in their in-house lab. Connected Development was able to support the customer in finding a suitable lab to conduct other testing.
Figure 2: VSWR testing of a sensor device in Connected Development's in-house anechoic chamber.
Designers can be confident in streamlining their design cycle through the use of Connected Development’s antenna testing services. The crucial considerations of antenna selection and functionality are made easy with Connected Development’s expertise and consultation. Designers can be rest-assured that minimal adjustments will be needed prior to entering an official lab. In addition to comprehensive antenna testing services, developers can leverage CD’s other engineering design services including end-to-end product design, prototyping, development, implementation, and more.
Interested in learning more about Connected Development’s innovative antenna testing services? Contact CD for pre-compliance antenna testing for your product design.