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A novel structure for implementing broadband external and internal coupling in heavily loaded, substrate integrated, evanescent-mode, cavity filters is presented. The proposed structure is based on adding electric field coupling to the magnetic field iris coupling, which is commonly used for such cavities. It is shown that fractional bandwidth on the order of 40% can be achieved using this new structure. As an illustration, a second order Butterworth filter is designed using the presented coupling method and then fabricated inside a two-layer RF circuit board. The measured and simulated filter results are shown to be in good agreement, with measured insertion loss of around 0.4 dB including connector losses. Finally, the filter is continuously tuned from 2910 MHz to 3795 MHz.

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In this paper, an accurate characterization of a fabricated X-band transmit/receive module is described with the process of generating control data to correct amplitude and phase deviations in an active electronically scanned array antenna unit. In the characterization, quantization errors (from both a digitally controlled attenuator and a phase shifter) are considered using not theoretical values (due to discrete sets of amplitude and phase states) but measured values (of which implementation errors are a part). By using the presented procedure for the characterization, each initial control bit of both the attenuator and the phase shifter is closest to the required value for each array element position. In addition, each compensated control bit for the parasitic cross effect between amplitude and phase control is decided using the same procedure. Reduction of the peak sidelobe level of an array antenna is presented as an example to validate the proposed procedure.