With the development of modern wireless communication technology, filters ODM industry usher in new opportunities and challenges: resource scarcity resulting spectrum communication system frequency allocation more intensive, in order to meet the system requirements and achieve their own transceiver multi-system sharing, which requires inhibition of the indicator improved filter; wireless system energy saving requirements need to be more stringent power control, in this condition, the filter unit must meet the high inhibition condition while achieving better band differential loss indicators; on the tower and the outdoor station and the system type evolving trend toward miniaturization of portable filter unit requires less space to achieve the desired performance targets.
In response to these needs Mobi offers the appropriate solution. Dielectric cavity resonator filter has many advantages in common: First: High Q; Second: By controlling the temperature coefficient of dielectric material resonant frequency can be precisely controlled in order to achieve an extremely stable full temperature characteristics. These two features ensure improved filter performance. We also can not ignore the dielectric filter in product development, manufacturing, especially in the realization of large-scale production, there are many challenges, primarily two major problems, one: high-order mode parasitic coupling product complexity a great impact for the master mode, greatly improving the simulation, especially debugging complexity. This requires high-order mode must be treated with its inherent characteristics, negative impact mitigation and strengthen effective use (such as multi-mode dielectric filter). Second: the complex tunable coupling structure.
Currently, TE mode and TM mode dielectric filter has a high commercial value for development.
TE mode relative air cavity can greatly improve the Q value (200% or more), but in the 1.5G band below, due weight and volume of the disadvantages and thus introduced many reliability problems, making it in this band's multi-cavity applications areas do not have much market prospects; But over and above for the 1.5G band, TE01 mode began to highlight the advantages: Because at such a high frequency band's request, most applications have been unable to increase the volume of the air chamber to improve the effective Q value, but this time to achieve the desired volume of TE mode and the air chamber has been fairly even dominant, and the weight is also controllable range. Become a high rejection, low insertion loss application of choice.
TM mode can be in the same volume of a metal coaxial resonator by 40% on the basis of Q, Q value or equivalent conditions improve space utilization. Although these are only limited performance boost, but certainly for the system design provides a valuable resource. Applications include: a: Series Station type seamless integration, TM mode filters for the series stand-type filters planning an equal volume provides a more high-performance choice. For device product planning, makes high-frequency low-band compatible, compatible with conventional performance special performance possible. 2: RRH Station type and subsequent micro-miniaturized base station type, due to system efficiency, you can use a smaller volume of the whole structure to reduce installation and maintenance costs, this time also requires filtering unit needs to maintain performance achieved under conditions miniaturized. Currently the biggest obstacle to the application of the TM mode from its own structural complexity resulting in products of bottlenecks.
The moment, the industry are actively exploring the development direction of the filter medium, but the technology is not the biggest bottleneck in the application materials prices (taking into account the overall cost of equipment, high performance, low installation and maintenance costs of wireless devices will be more affected by the operator's favored), but with the large-scale commercial applications related features: structural reliability, stability, batch consistency, size and so on.