Research On 5G Millimeter Wave End-fire And Broadside Terminal Package Antennas

As a key component of mobile communication system,the antenna plays a very important role.In 5G millimeter wave band,terminal equipment has some special requirements for antennas such as polarization,radiation direction,and size(profile).However,in terminal equipment,the increase of antenna number and the reduction of antenna space make antenna design more difficult.In addition,antenna-in-package is an effective solution for 5G millimeter wave terminal antenna to overcome the interconnection loss.Thus,its research has important practical significance.This article focuses on the research of 5G millimeter wave terminal package antennas.The main contents are as follows:1.An ultra low profile broadband broadside antenna is proposed.The antenna is based on multiple patch antennas and they are series fed.By using the working principle of log-periodic antenna and enlarging the size and space of the patches according to a certain proportion,the antenna could achieve wideband performance at low profile condition.On the basic of above antenna,the radiation patterns of different frequencies could be optimized using differential feeding.Under the premise of wideband performance,the gain of antenna is increased and the stability of pattern is improved.The proposed antenna adopts microwave substrate with a thickness of 0.254 mm(0.02?₀),and covers the 5G millimeter wave band(24.25-29.5 GHz,?20%)at full ground condition.The experiment results verify the proposed design idea.2.A broadband horizontally polarized end-fire antenna is proposed.Firstly,the antenna uses a two-step evolution of helical antenna,and then adopts the working principle of log-periodic antenna to expand the bandwidth.Finally,a log-periodic antenna based on gradually enlarged folded dipoles is obtained.The folded dipole is fed by a microstrip-to-slot balun,which could convert the single ended signal into differential signal.In order to improve the gain,a1×4 array is designed.The antenna array is implemented by LTCC process with nine layers and covers the 5G millimeter wave band.The experiment results verify the proposed design idea.3.A low-profile broadband vertically polarized end-fire antenna is proposed.The antenna is based on a radiating element with end-fire vertical polarization called quasi-PIFA antenna.The first antenna adopts L-shaped probe feeding structure,loaded patches,and U-shaped slot to broaden the bandwidth and covers the n257 band.The loaded patches could be used not only as a resonator to broaden the bandwidth,but also as a director to increase the gain.In order to further improve the bandwidth and the gain,the U-shaped slot of the first antenna is removed and replaced by another pair of loaded patches.Then the dual patches loaded antenna is obtained.This antenna covers 5G millimeter wave band and has higher gain than the first antenna.Two 1×4 arrays are designed based on the above two antenna units.Both antennas use9-layer LTCC process with a thickness of 0.846 mm.The experiment results verify the proposed design idea.4.A low-profile broadband dual-polarized end-fire antenna is proposed.The antenna is based on a pair of vertically polarized end-fire antennas,and two loaded patches are used for horizontal polarization.This antenna adopts multiple structure reuse technology,which can not only realize dual polarization in a single structure to reduce the volume by half,but also increase the gain and bandwidth of two polarizations.In addition,the horizontal polarization and vertical polarization are fed by differential signal and common signal respectively.Thanks to the symmetry of antenna structure and feeding signal,the two polarizations of antenna are naturally isolated.The antenna uses 9-layer LTCC process and covers n257 band.The antenna unit and its 1×4 array are fabricated and tested.The experiment results verify the proposed design idea.