It is known that for a microstrip antenna, if the height of the antenna is strictly limited, then the bandwidth is narrow. A way to solve this problem is to combine two modes. However, for almost all the two-mode resonant patch antennas reported, the height of the antenna conflicts with the frequency ratio of the two modes. The smaller the frequency ratio is, the higher the antenna. In this paper, a detailed mode analysis is performed, and a comprehensive mode shift design method is established. A dual resonant patch antenna with any frequency ratio can be designed. Guided by this method, a low-profile wideband patch antenna with a size of only 0.6λ0 × 0.6λ0 × 0.05λ0 for the universal RFID reader (840-960 MHz) is designed. The simulated and measured results show that a low-profile is achieved for universal RFID reader antennas.

众所周知，对于微带天线，如果严格限制天线的高度，则带宽很窄。解决这个问题的一种方法是结合两种模式。然而，对于几乎所有报道的双模谐振贴片天线，天线的高度与两种模式的频率比相冲突。频率比越小，天线越高。本文进行了详细的模态分析，建立了综合的模态转换设计方法。可以设计任意频率比的双谐振贴片天线。在此方法的指导下，设计了一种尺寸仅为0.6λ0 × 0.6λ0 × 0.05λ0 的低剖面宽带贴片天线，用于通用RFID 阅读器（840-960 MHz）。模拟和测量结果表明，通用 RFID 阅读器天线实现了薄型。