Design Of Miniaturized Antenna And Filter Based On LTCC

With the endless development of wireless communication technology and demand,the high integration of radio frequency modules became inevitable.Low Temperature Co-fired Ceramic(LTCC)provides a better solution for the miniaturization of RF module devices due to its flexibility in dielectric constant,high reliability,and ease of integrated packaging.This paper uses the LTCC process to design the antenna and filter in the RF module with miniaturization and high performance.The main contents are as follows:(1)Single-frequency PIFA(Planar Inverted F-shaped Antenna)antenna design.Traditional PIFA antennas are encapsulated with ceramic dielectrics to achieve miniaturization.Capacitive coupling is introduced into the traditional structure,and the design of grounding at both ends is used to further reduce the size of the antenna.The final antenna size is 3.2mm×1.6mm×0.8mm,which is much better than the traditional PIFA antenna.At present,it has been mass-produced,with an annual output of about 2 million pieces,and is used in various mobile networking devices.(2)Dual-frequency PIFA antenna design.A design scheme of left and right isolated double branches is proposed,which facilitates relatively independent adjustment of the two resonant frequency points,instead of the traditional scheme of slotting the main radiating surface of the PIFA antenna to achieve dual-frequency design.The performance of the finally produced antenna meets the requirements,and the size is only a little higher than that of the single-frequency antenna,and the actual size is 3.2mm×1.6mm×1.2mm.This dual-band antenna has also been put into mass production,with an annual output of about 1.5 million,which is used in various multi-band wireless communication devices that support WIFI,Bluetooth and other communication protocols at the same time.(3)Ultra-wideband bandpass filter design.Based on the principle circuit of high and low pass cascade,a compact three-dimensional structure is designed by analyzing the layout position of capacitor and inductor.Aiming at the passband performance of the filter,it is proposed to apply the impedance matching idea to the filter adjusting.After optimization,better return loss and passband insertion loss are finally obtained.The filter is produced by the LTCC process,and the size is only 1.6mm × 0.8mm × 0.7mm.It has been put into production at present,with an annual output of about 500,000 pieces.(4)Design of wide stopband high rejection bandpass filter.In view of the parasitic effects that are prone to occur in the RF field,on the one hand,by designing the conjoined ground inductance structure,and simplifying the internal design of the filter,the transmission zero point is added to improve the out-of-band suppression of the filter;on the other hand,the parasitic effect is reasonably utilized,The introduction of multiple parasitic resonance zeros simplifies the design of the internal three-dimensional structure of the filter,and achieves wide stopband and high suppression.The actual size of the filter is 1.6mm × 0.8mm × 0.7mm,and it has been put into mass production,with an annual output of about 3 million.