The modulation circuit utilized the vector modulation technology based on fourth - harmonic mixer . the lo frequency is only quarter of carrier frequency . direct high speed qpsk digital modulation of millimeter wave signal can be realized with fairly simplified lo circuit 调制电路采用了以四次谐波混频器技术为核心的矢量调制技术，利用1 / 4载波频率作为本振信号，实现了对毫米波信号直接进行高速qpsk数字调制。
According to the proposal , two millimeter - wave phase locked sources are locked on a crystal oscillator . the one of the phase locked source is used for steady carrier wave in transmitter , the other is used for local oscillator . through the proposal , coherent transceiver front - end is achieved 本方案采用同一晶振源为收发两个毫米波锁相源作参考频率,其中的一个锁相源用于产生高稳定的发射载波频率,另一个用于产生高稳定的本振信号,从而实现收发的相参性。
Mixers are the key components of many microwave and millimeter - wave systems . the super - heterodyne receiver is always applied in modern communication system , mixer becomes the key component as is at the first part of system . but it is more and more difficult to get the choiceness lo source of the same band with the system is working at high frequency especially in the millimeter - wave . sub - harmonic mixer is a good solution to this problem now . in this circuit we need just half 、 quarter 、 even 1 / 8 of the rf signal frequency . in this paper the design and fabricate of sub - harmonic hmic mixers ( 2 , 4 ) at w - band are introduced 混频器是微波通信、射电天文学、雷达、等离子物理、遥控、遥感、电子对抗,以及许多微波测量系统中至关重要的部件。在现代通信系统中,毫米波频段通常采用超外差接收机,混频器作为第一级就成为关键部件。由于在毫米波频段,同频段高性能的本振源成本高,技术难度大,采用分谐波混频技术是解决此问题的有效途径,只需射频频率1 / 2 、 1 / 4甚至1 / 8的本振频率即可实现混频。
The mm - wave section contains quadruple multiplication stage and iq modulation part . measurement has testified that triple - tuning of dds frequency 、 reference divider ratio 、 and loop divider ratio avoided frequencies with high spur level while ensuring the realization of total frequencies . the spur level is below - 55dbc and frequency resolution reached 100khz ; dds output frequency was up - converted to drive the m / n pll , reducing phase noise , which is better than - 87dbc / hz @ 1khz , - 92dbc / hz @ 10khz , decreasing frequency - hopping time which is less than 14us 系统分为微波与毫米波两大部分,微波部分综合利用了dds 、 lo混频锁相环和rf混频锁相环实现两路频差15mhz的xband全相参信号;毫米波部分,将xband本振信号四倍频得到毫米波本振; xband载波信号经开关控制形成脉冲信号,倍频、 iq调制后得到毫米波发射信号。
Intermodulation suppression for fh ( frequency hopping ) receiver is designed by selecting the intermediate frequencies and changing group of filters , local oscillation ( lo ) frequency , bandwidth of lo frequency under the condition that receiver configuration , sensitivity , dynamic range , instantaneous bandwidth and precision of frequency measurement are fixed 摘要针对跳频接收机的体制和灵敏度、动态范围、瞬时工作带宽、测频精度等设计参数，通过改变预选器组成、本振频率和本振带宽，分析接收信道的中频选取原则，以实现跳频接收机的互调抑制设计。
3 . with comprehensive improvement of transponder including structural adjustment to lna ; optimization of ( phase locked loop ) pll filter ; structural adjustment to the transmitter and phase error adjustment to the intermediate frequency demodulation circuit , we have successfully enhanced sensitivity , expanded dynamic range , increased transmitting power and improved the spectrum purity ; decreased capture time for pll ; improved the signal quality after demodulation ; reduced its volume and power consumption . 4 3 、对通信机的全面改进，包括lna结构的调整、锁相环环路滤波器的优化、发射部分结构的调整以及中频解调电路的相差调整，提高了系统的接收灵敏度、改善了本振的频谱纯度、减少了锁相环的锁定时间、使中频解调后的信号质量大为提高，同时还减少了体积、节约了系统的功耗。
Based on the results of the theory analysis and computer simulation of suspended stripline low pass filter , band pass filter , the transition from waveguide to finline and the transition from waveguide to suspended stripline , the structure design and manufacture were made . the measured results match the requirement . different from the traditional mixers used in the domestic communications satellites , the sub - harmonic balance mixer type was used in the ka - band mixer design 在ka频段混频器的研究过程中，通过对卫星和飞船所用到的混频器进行研究，在对ka波段的传统射频前端电路的分析基础上，提出改变以往星上传统的基波混频方案，采取了次谐波混频方案，降低了本振频率，简化了本振链路，使噪声特性、可靠性获得改善。
The design process consisted of computer design by circuit simulation software integrate with electromagnetic simulation software , fabrication of microstrip bpf 、 lpf 、 the match circuits , cavity and test . when rf frequency is 91 ~ 97ghz , lo frequency is 47ghz , power is 10 dbm . the best conversion loss of the 2 and 4 sub - harmonic mixer is 13 . 5 db and 23 . 5db which is shown in the test 实测表明,在本振为47ghz ,功率10dbm ,测试射频带宽为91ghz 97ghz时,二次与四次分谐波混频器变频损耗最优处分别为12 . 7db和23db 。最后对实验结果进行分析并提出改进措施。
According the demands with frequency source by full - coherent mm - wave radars , this paper combined the three styles of frequency synthesis and developed a type of low - phase noise and spur 、 narrow - step 、 frequency - agile 、 coherent mm - wave frequency synthesizer . it comprises of two sections : microwave section and mm - wave section . microwave section includes dds 、 pll and x band frequency multiplication chain 本文根据全相参毫米波雷达对频率源的要求,在理论分析的基础上将dds和m / npll相结合,研制出一种窄步进、捷变频的kaband全相参毫米波频率源,输出kaband本振和发射两路信号,频差60mhz 。
With the established rf front - end system simulation platform , adding the digital modulated baseband signal , this paper simulated the multifold digital modulated signal ’ s transmission , such as 2ask , qpsk , and 16qam . then researches of power compression and phase noise of local oscillation influence the bit error ratio for different modulated system . the designing is satisfied multifold functions request with the high - powered and integrated broadband rf front - end 随后在建立的宽带射频前端通用仿真平台上,加入基带数字调制信号,对多种数字调制格式的信号在该通用平台上的传输作了研究,模拟了2ask 、 qpsk和16qam等调制格式信号的发射与接收,研究了功率压缩和本振相位噪声对不同调制的误码率影响,实现了满足多种功能要求的宽带高性能综合射频前端的设计。
