A low cost X-band HMIC vector modulator

A low cost X-band HMIC (hybrid microwave integrated circuit) vector modulator used in a 9-10GHz phase controlled array radar system is designed by using unpowered FETs as the control elements. Due to the effect of FET parasitic parameters, bi-phase modulators are not ideal 180° phase difference, and thus the dynamic range of the HMIC vector modulator is reduced. In order to widen the dynamic range, the characteristic impedance of the bi-phase modulator has increased to 70 ohm from 50 ohm. The final measurement results show that the analogue control of the HMIC vector modulator extends over a range of 14dB for amplitude and over 0-360 degrees for phase at the frequency of 9.6GHz, and that the mean square errors of the phase are lower than ±5° for a 3.1% instantaneous bandwidth wherever in 9-10GHz.