COMMUNICATIONS TECHNOLOGY Placement of antennas in patient rooms with telemetry communication Good radio wave transmission


Whip antenna (for patient room)


Ceiling panels (non-metal)


Securing the path of wires through beams


Ensuring safe distance 50 cm or more


Cable


Lighting equipment (electrical)


Toilet Patient room Corridor


Whip antenna (for a corridor)


attention to securing an appropriate wiring space.


Door (steel)


Deck plates (steel)


n Good communication n Poor communication


Suppresses unwanted electromagnetic interference to and from areas outside the room (downstairs)


Figure 1. Points to be considered when locating cables and antennae.


telemetry. The medical telemetry systems covered by the guidelines are limited to equipment that meets the criteria of the Radio Law of Japan, RCR STD-21, established by the Association of Radio Industries and Businesses (ARIB) of Japan and JIS (Japan Industrial Standard) T 1304. The typical configuration of a medical telemetry system is shown in Figure 2. The frequency of the radio waves used is within the range 420 MHz-450 MHz, and in this range six bands are defined. One channel with a bandwidth of 8.5 kHz is assigned to each monitored subject (patient), and the patient is identified by the channel. The output power of the transmitter on the patient side is 1 mW in Japan.


Points to be considered in the design stages At the basic design stage, information on installation requirements and building plans should be shared among the parties concerned (architectural designers, hospital personnel, and medical device manufacturers and distributors), and plans for antenna placement, wiring routes, and the radio wave environment in the building, made appropriately. To ensure a high quality design, consideration should be given to the patient’s range of movement and the antenna’s communication range, the antenna’s placement and wiring path, the construction materials and fittings to be used, and the equipment and devices that will be in close proximity. Japanese medical telemetry systems


employ at least two different types of antenna system: one uses whip antennae and the other leaky coaxial cables. Hospital personnel should decide on the specific medical telemetry system to be installed as early as possible. The architect will need to plan the building based on as much specific information as possible, such as the range of movement of patients wearing transmitters, and the type(s) of antenna to be employed.


Through the cooperation of the medical equipment manufacturers and distributors in the design implementation stage, the medical telemetry system and related equipment and devices should be coordinated to eliminate the possibility of mutual interference, and the placement of each device should be carefully studied.


Install antennae before constructing the ceiling The points to be considered in the planning of antenna placement and the wiring route are almost the same as those to be considered in the basic design. It is desirable to install the antennae before constructing of the ceiling, but even if the installation work is done after construction, it is important to ensure that the wiring route is such that the antenna wiring can be easily installed.


Points to be noted during construction At the time of installation, medical device manufacturers and distributors should inform the installer of their requirements for antenna placement, the wiring route, and other needs particular to their devices in order to prevent signal reception disturbance during installation. The designers and installers must pay special


Antenna system (in the ceiling)


Door (steel)


When undertaking the wiring work, it is important to confirm on site that a safe distance is kept between the antennae and metal objects such as air-conditioning ducts, and between wiring and electrical equipment that might be possible sources of electromagnetic noise radiation that could affect the performance of the antenna. In addition, because it is likely during the construction phase that there will be changes in the location and number of wiring conduits and pipework planned at the design stage, any changes need to be clearly communicated to all parties concerned, to ensure that the changes can be correctly made. With the pipework, once the wiring for the medical telemetry system is completed, it is important to ensure that the compartment is fire-proof, and that there is adequate insulation.


Evaluation of communication quality as per the guidelines It is important that the hospital staff check and pass along information on the radio wave environment before and after the installation of antennae. What is key here is to prevent radio wave transmission issues, and investigate any existing problems, such as poor reception, and then determine the best way to respond to them.


Our guidelines recommend the


measurement of the radio wave environment before and after the installation of antennae. There are also specific guidelines for the method to be used – including the measuring equipment to be used, the number of measurements, the frequency band to be measured, the measurement procedure, the measurement location, and the method used to set out the results. The purpose of conducting a radio wave


environment survey before positioning the antennae is to confirm the presence or absence of radio waves from other facilities in the vicinity, or within the same hospital, as well as radio waves from other wireless devices that use the same frequency band as the medical


Amplifier


Transmitter Corridor Central monitor Patient room Staff station Figure 2. The configuration of a typical Japanese medical telemetry system. November 2022 Health Estate Journal 31


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