This letter presents a frequency-tunable, dual-function, microwave filter with both bandpass and bandstop functionalities. The filter uses a single switch to change the functionality minimizing the insertion loss, and it can replace a traditional filter bank structure that contains two filters and two switches. Frequency-tunable substrate-integrated waveguide (SIW) resonators are adopted in this filter design. Measured results show that both bandpass and bandstop responses can be tuned from 3.0 GHz to 3.6 GHz. The measured minimum insertion loss at the center frequency is 1.1 dB for the bandpass mode and the attenuation at the center frequency is greater than 40 dB over the entire frequency tuning range.

To increase the mobility of an unmanned ground vehicle, this study describes new approach to detect targets in front of mono-static terrain imaging radar (TIR), which is a prototypical ground-based forward looking radar. Since the TIR employs a mono-static configuration and a real aperture antenna array, the conventional back-projection method is very useful in spite of its poor processing time. However, it is difficult to employ another method because the TIR is an ultra-wide-band type of radar and employs a dechirp-on-receive process. To overcome these difficulties, a new approach based on scaling function processing is proposed in this study. This scaling function is based on a spectral analysis approach and the proposed method conducts range cell migration compensation, secondary range compression and azimuth compression using this scaling function. In this study, the complete derivation of the proposed method is presented. A very useful formulation for a dechirped mono-static radar signal in the range Doppler domain is also proposed, in which the signal is expressed by the scaling function. The results of simulations and field tests are demonstrated to show the performance and validity of the proposed method.

No abstract