n in these 'large local markets' the entry costs and risks of nonstandard bands were in practice much higher than generally acknowledged. Take intermodulation as an example. 4.3.4 Intermodulation Whenever two or more frequencies are mixed intentionally or unintentionally within a handset, they will produce sum and difference frequencies. This is known as intermodulation and can occur at receive frequencies and transmit frequencies or between transmit and receive frequencies. Frequencies are mixed or multiplied together intentionally within the frequency synthesiser to create new wanted frequencies to be modulated. The unwanted sum or difference frequency (the image) is filtered out. When frequencies mix together unintentionally, sum and difference products may translate unwanted signal energy into other bands within the phone or into other proximate devices. A new frequency band introduced into a handset will create a new set of intermodulation products that will need to be managed in terms of their potential impact on the other bands and radio systems used in the phone. Resolving these issues adds to the nonrecurring engineering cost, may result in time to market delay and may add to component cost if additional filtering or reciprocal mixing has to be introduced. 4.3.5 The Need to Support Higher Frequencies and Linear Power Efficiency The new extension/expansion band at 2.6 GHz and bands at 3.5 GHz creates new challenges. Many countries have legacy wideband radar systems at 2.6 GHz that are problematic but the 2.6 GHz transceivers also have to work with WiFi transceivers at 2.4 GHz These are low power devices, generating not more than 10 milliwatts of transmit power. Wide-area cellular systems require handsets to transmit at higher powers, typically 250 milliwatts, and to be able to reduce this output power in defined steps down to a few milliwatts (the dynamic output power range over which the phone has to operate). Handset vendors have a choice of power-amplifier technologies that are typically either based o