One of the major agenda items for the recent World Radiocommunication Conference (WRC-15) was to identify more frequency bands for mobile communication, and the 2.7–2.9-GHz band has been under consideration. The latter band is used by radio navigation radars (civilian and military) in addition to weather radars. So far a majority of the reported interference cases is from C band, but there is a growing number of cases from S band as well. When another device is emitting microwaves at the same or nearby frequency as a weather radar, the radar may receive interference, its measurements disturbed, and the output images may manifest typical interference signatures such as dots, spokes, or stripes. But other players, especially the wireless communication industry, are keen on utilizing the same frequency bands. The most common microwave frequency ranges for this purpose are S band (2–4 GHz), C band (4–8 GHz), and X band (8–12 GHz), within which certain subbands have been assigned to weather radar on a primary basis. Weather radars work by sending and receiving microwave pulses. When nearby devices transmit at the same frequency, we see the disturbances as dots and spikes in the radar image. When nearby devices transmit at the same frequency as weather radars, the resulting disturbances can severely limit the usefulness of the radar images. Hence, it is an important task for the worldwide weather community to involve themselves in the radio frequency management process and work in close contact with their national radio authorities to ensure that meteorological interests be duly taken into account in any decision-making process toward the future usage of wireless devices. If wireless devices use these technologies to protect weather radars, their data transmission capabilities become limited, so it is tempting to violate the regulations. Technologies have been developed for peaceful coexistence. Use of equipment at radio frequencies is regulated by laws and international agreements. Some agencies have already changed or are considering changing frequency bands, but now even other bands are under threat. One or two disturbances can be removed from the radar image, but the number and power of the interfering wireless devices are growing all over the world, threatening that one day the radars could become useless for weather observations. Wireless technology, such as local area telecommunication networks and surveillance cameras, causes severe interference for weather radars because they use the same operational radio frequencies.
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