Design and Microwave Measurement of a Novel Compact TE $_{0n}$ /TE $_{1n'}$ -Mode Converter

A novel method to generate a TE
_0n
^(C)
(n = 1, 2, 3) (C is circular for short) or TE
_1n'
^(C)
(n' = 2, 3, 4) mode via a TE
_m0
^(R)
(m = 2n or m = 2n' - 1) (R is rectangular for short) mode generator is proposed in this paper. Two main components, including a TE
₁₀
^(R)
-TE
_m0
^(R)
mode converter with multiple coupling apertures and matching steps and a TE
_m0
^(R)
-TE
_0n
^(C)
or TE
_1n'
^(C)
mode converter, were, respectively, demonstrated. Two novel compact mode converters, respectively, exciting the TE
₀₁
^(C)
and TE
₁₃
^(C)
modes at Q- and W-band based on the aforementioned methodology were designed and analyzed. In the TE
₀₁
^(C)
mode converter design, symmetric cylindrical ridges were introduced to improve the mode purity and suppress the unwanted TE
₂₁
^(C)
mode by cutting off its surface current on the metal wall. Such a mode converter operating at Q-band was manufactured and vector network analyzer measurements showed excellent S-parameter performance (port reflection <;-12 dB) and mode purity (>90%), which agreed very well with our simulation. Besides, as an expansion of the TE
₀₁
^(C)
mode converter, the designed results of a high-order TE
₁₃
^(C)
mode converter excited by a similar methodology were also presented.