Frequency Agility in Microwave Dielectric Resonators

目前。蜂窝移动通信系统使用输入和输出滤波器，其被调谐以覆盖整个感兴趣的频段。这样做是因为不存在损耗足够低或本身不会产生显著不需要的信号的可调谐滤波器。例如，可以使用变容二极管来调谐滤波器，但这些是非线性设备，会产生不需要的信号，对于商业通信系统中的滤波器来说，这些信号太大了。它们还具有较低的空载0，这会导致滤波器具有较高的插入损耗。可以调谐到单个通信通道的低损耗、低杂散干扰的滤波器将在系统其余部分的设计中提供巨大的优势。它们是：在接收器的较早阶段排除与您自己的信号处于同一频段的信号的能力。这将大大减轻频谱规划的问题，并大大提高频谱效率和用户(公众)可获得的信息传输能力。光谱才是。当然，这是一种独特的、有限的资源，因此任何频谱效率的提高都是值得的。大幅减少发射机辐射的无用信号量的能力。3G通信系统的功率放大器的设计比GSM系统的设计困难得多。例如，放大器必须具有线性传输特性。这对于GSM不是必需的。为了实现这种频率敏捷性，我们打算检查两种方法。这些是铁电/顺电调谐--电压会改变材料的相对介电常数，从而改变频率。2压电调谐--调谐元件位置的变化会改变频率。为了验证这些想法，将制造并测试每个调谐元件的原型装置。原型将包括*单谐振双模2极滤波*2谐振双模2极滤波和2谐振双模4极滤波

At present. cellular mobile communication systems use input and output filters which are tuned to cover the whole band of interest. This is done because tuneable filters that have low enough loss or do not themselves produce significant unwanted signals do not exist. For example, filters can be tuned by using varactor diodes but these are nonlinear devices which produce unwanted signals that are too large for the filters to be used in commercial communication systems. They also have low unloaded 0 which result in filters with a high insertion loss. A low loss, low spurious interference, filter which could be tuned to a single communications channel would offer tremendous advantages in the design of the rest of the system. These are:The ability to exclude, at an earlier stage in the receiver to that currently possible, signals in the same band as your own. This would considerably ease the problems of spectrum planning and greatly improve spectrum efficiency and the information transfer capacity available to users (the public). Spectrum is. of course, a unique, limited resource, so any spectrum efficiency improvements are worthwhile.The ability to reduce greatly the amount of unwanted signals radiated from a transmitter. The design of power amplifiers for 3G communication systems is much more difficult than for GSM systems. For example, the amplifiers must have a linear transfer characteristic. which is not required for GSM.In order to achieve this frequency agility we intend examining two methods. These are1 Ferroelectric/paraelectric tuning - where a voltage will alter the relative permittivity of the material and hence the frequency.2 Piezoelectric tuning - where a change in the position of a tuning element will alter the frequency.In order to verify these ideas, a prototype device of each will be manufactured and tested.The prototype will comprise* a single resonator dual mode 2 pole filter* a a 2 resonator 2 pole filter and a 2 resonator dual mode 4 pole filter