Frequently Asked Questions
What is the difference between a double wall and single wall enclosure?
A double wall enclosure is built with two layers of aluminium with an air gap in between. The dual-layer provides excellent RF isolation in the order of about 100dB. A double wall enclosure is designed to have its inside and outside connector panels offset at a distance to maximize RF isolation. The interconnecting cables between the internal I/O panel and external I/O panel are routed in between the two walls of the enclosure.
How can a double-wall design increase the isolation of an RF enclosure?
Shielding effectiveness is a measurement of how much RF isolation can be achieved between the RF signals from the inside and outside of the enclosure. This specification is given in terms of dB over a specified frequency range. For example, 90 dB from 300 MHz to 6 GHz, means that between 300 MHz and 6 GHz, the RF enclosure guarantees 90 dB of isolation.
There are a few reasons why this is important in wireless testing, and especially considering the types of wireless devices that are being developed today. Removing the outside world from the testbed ensures that the DUT and the results are not being impacted.
For example, if your corporate Wi-Fi network is transmitting at +20 dBm and your enclosure has 60 dB of isolation, your DUT could potentially lock onto your corporate Wi-Fi network since it will see an RSSI of -40 dBm.
In certain cases, such as GNSS (GPS) testing, it is the outside world that should be shielded from what is being tested inside the enclosure, as fictitious GNSS signals could cause serious issues with airplanes and other devices which rely on positioning data.
Is RF isolation the most important spec in selecting an RF enclosure?
Yes, but one of many. Flexible custom I/O panels, different sizes, and quality construction all play a role. Durability is also very important in determining how your RF enclosure’s shielding will perform over time.
Starting with the right materials, each and every DVTEST enclosure is engineered and manufactured to provide the best isolation so you can get better results.
What is the difference between a rackmount enclosure and a standard unit?
DVTEST Rackmount enclosures are engineered to be used in standard 19 inch and 24-inch racks. DVTEST enclosures are front load and can be stacked with zero clearance if multiple units need to be placed in a rack. Ventilation can be placed on the front, back or sides of the enclosure(s). In addition, I/O panels can be positioned and split by technology (grouping for RF, data, power, etc), optimizing their position for performance, while minimizing interference.
What is Tri-Shielding and why is it important?
DVTEST incorporates a proprietary form of chromate conversion called Tri-Shielding to the aluminium surface of our RF enclosures. This extensive process bonds with the surface of the aluminium, and when used in conjunction with the painting process, creates a maintenance-free surface that is corrosion-resistant.
This process is even more important on non-painted surfaces. When aluminium oxide forms on the surface, it also gets on the gasket, causing a resistive layer to develop on the material resulting in a change to its resistive properties, degrading the isolation performance over time.
DVTEST RF enclosures are built to last. The DVTEST process is compliant to the most recent MIL-DTL- 5541F (2009) specifications.
Does adding more connectors on an I/O panel affect isolation?
Yes, all penetrations into the panel assembly will cause the possibility of undesired RF signals passing through the RF enclosure. Mitigating these signals can be achieved through proper mating of the feedthroughs to the I/O panel, and the I/O panel to the enclosure assembly, with very close mechanical tolerances and gaskets.
Using an RF enclosure with an offset I/O panel will greatly improve shielding effectiveness. Competitive enclosures do not use an Offset panel, and/or have poor mechanical interfacing to the main assembly, causing a loss in shielding effectiveness.
Do our enclosures support direct fiber ports?
Yes, DVTEST offers up to a 10-channel direct fiber port module as an option on every enclosure. This is most popular on our dbSAFE ARMOR Series enclosures. We also offer fiber access through a separate waveguide filter module that can also be used for cooling.
What is an offset I/O panel?
The majority of DVTEST enclosures utilize a double-wall design. This design allows the position of the internal I/O panel of the RF enclosure to be different from the corresponding external I/O panel. This is useful in applications where connectors may need to be placed on multiple internal I/O panels while maintaining a single external I/O panel. The also allows you to select different connections on the inside (typically DUTs) versus the outside of the RF enclosure (typically test equipment like VNAs, Spectrum analyzers, Base station emulators and power supplies).
Do all your enclosure products test 5G devices?
Yes, every DVTEST enclosure is equipped to test 5G devices.
What is OTA?
OTA is an acronym for over-the-air. In regard to wireless testing, OTA testing refers to testing that is done when two devices are connected via a wireless interface as opposed to a cabled interface (conducted).
Historically, conducted testing was done by removing the antenna on a device connecting an RF cable directly to another device or piece of test equipment. With the recent innovations in MiMo technology, embedded antennas, and antenna arrays, conducted testing has become almost impossible in some cases so OTA testing has become the accepted practice.
When doing OTA testing, special care must be taken to understanding if the test is being done in the near-field and the far-field.
What is the difference between active and passive cooling?
Passive cooling typically has one vent, using passive convection to displace hot air. Active cooling adds a second waveguide vent and high-performance fans (AC or DC) to move air with controlled and balanced pressure.
Both active and passive cooling use DVTEST’s waveguide technology.
How do you vent your enclosures?
Ventilation is a key design element for RF enclosures as some devices emit a large amount of heat that can detrimentally alter test results and RF performance. The challenge with ventilation is being able to allow airflow in and out of the enclosure while still maintaining RF isolation.
DVTEST provides two forms of ventilation - Passive and Active Waveguide. A waveguide is a precision designed conduit that allows air to flow through it. Based on its geometry, waveguide operates like a high pass filter, allowing the enclosure to maintain rf isolation. The passive waveguide allows air to naturally flow in and out of the enclosure, while the active waveguide utilizes a fan to force air in one waveguide and out the other.
The size of the actual waveguide can be customized to suit airflow requirements.
Why is thermal testing important?
Temperature changes the physical characteristics of materials and the RF performance of devices.
The world is becoming more connected, meaning more devices will be used outdoors or in extreme conditions. One common method of test is to perform sequential thermal and rf testing. Normally a customer will heat or cool a DUT, and then transfer this device to an RF bench. This starts changing the temperature of the device while the customer is trying to test. We can precisely control the temperature indefinitely as well as being able to “thermally shock” the device. To fully characterize an RF device, both thermal and RF testing should be done together. We offer various options for thermal and RF testing.
Do you customize enclosures?
Yes! Excluding the dbSAFE Classic, all DVTEST enclosures can be customized to fit your unique needs.