Frequency Agility in Microwave Dielectric Resonators

目前。蜂窝移动的通信系统使用输入和输出滤波器，这些滤波器被调谐以覆盖感兴趣的整个频带。这样做是因为不存在具有足够低的损耗或本身不产生显著的不想要的信号的可调谐滤波器。例如，滤波器可以通过使用变容二极管来调谐，但是这些是非线性器件，其产生对于在商业通信系统中使用的滤波器来说太大的不想要的信号。它们还具有低空载0，这导致滤波器具有高插入损耗。一个低损耗、低杂散干扰的滤波器，可以调谐到一个单一的通信信道，将在系统其余部分的设计中提供巨大的优势。这些是：排除的能力，在较早的阶段，在接收器，目前可能的，信号在同一波段作为自己的。这将大大缓解频谱规划的问题，并大大提高频谱效率和用户（公众）可用的信息传输能力。光谱是。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。2这种能力可以大大减少发射机辐射出的无用信号的数量。第三代移动通信系统中功率放大器的设计比GSM系统中的功率放大器的设计要困难得多。例如，放大器必须具有线性传输特性。为了实现这种频率捷变，我们打算研究两种方法。这些是1铁电/顺电调谐-电压将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将改变频率。为了验证这些想法，每一个的原型设备将被制造和测试。原型将包括 * 一个单谐振器双模2极点滤波器 * 2谐振器2极点滤波器和2谐振器双模4极点滤波器

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