Why are Two Way Radios so Bigger than Cell Phones?

While two-way radio devices allow for voice communications just like cell phones, they are very different than mobile cell phones on many levels. Two-way radios are used by professionals in the industrial and government areas of society, whereas cellophanes are used mostly by consumers. Cell phones are one-to-one communication devices, whereas two-way radios are one-to-many communication devices. Cellophanes are used for individual calls, whereas two-way radios are used primarily as a communications tool for the organization.

Typical power levels are about 1-5W. In contrast, Cell phones are typically 0.6W.  Because the cell sizes are larger for two-way radio systems, the talk-in range of the portable radio must be compensated with higher power output…up to a point.  A smaller cell size gives cellular systems more capacity. More capacity means more cellular call handling capability, and therefore more revenue. Contrary to cellular design philosophy, two-way radio systems benefit more from larger cell sizes - the larger the two-way radio cell, the better, because a larger two-way radio cell size is able to capture more portable radios to talk to.

Two-way radio systems have these features – direct mode operation or repeater talk-around – as a last resort form of communications in case the portable radios lose connectivity with the infrastructure. This allows the users to communicate directly with each other without the use of the infrastructure. Higher power output levels increases the reliability of the communications between the radios since the higher power level overcomes the signal path loss better in many environments. Direct mode bypasses the infrastructure. If a cell phone user used direct mode, there would be no way to track the airtime usage for billing purposes.

The need for high power amplifiers (PAs), which are larger in size, causes the internal design of the portable radio to be limited in how much it can shrink in overall size. Unlike cell phones that operate at 0.6W, portable two-way radios operate in the 1-5W range.  Because of the higher power levels, the two-way radios must be designed to higher RF performance specifications than cell phones.

Two-way radios are found in many industrial environments that are high noise or have a lot of background noise.  Unlike cell phones where users put the device directly on their ear, two-way radios use a loudspeaker that must be able to operate in loud environments. Loudspeakers require higher amperage to drive the speaker element to create the appropriate audio sound pressure for the user to hear the receive audio above the noisy environment. The higher amperage requirements for a loudspeaker require a larger battery requirement, which impacts the size of the radio.

Operating in rugged, highly industrialized, and possibly hazardous environments, two-way radios require much thicker housings, stronger metal frames and critical sealing from hazardous environments in order to work under such extreme conditions.  Try dropping your cell phone a few times in your office. It will break. Ruggedized industrial-grade two-way radios do not break under normal conditions in industrial environments. This requires special silicon sealing, ultrasonic welding, and high strength bonding materials. All of this requires additional space to add all of this for a good, tight seal.