Characterization of a millimeterwave integrated BCB patch antenna InP HEMT receiver array

A millimeterwave 1×4 integrated antenna receiver array for imaging applications is presented. Antenna elements and microstrip circuits are patterned on a relatively thick layer of BenzoCycloButhene (BCB). We use InP HEMTs working in a resistive mode as mixer elements. At an RF of 35 GHz we obtain a minimum conversion loss of 8dB at an LO power level of between 1 and 2 dBm. Active element directivity diagrams measured in an anechoic chamber show reasonably small variations between receivers in an array and a typical cross-polarization level around ¿15dB. A number of passive BCB breakout circuits have been measured. Their performance are found to be in excellent agreement with-calculations. An alternative LO distribution method using a direct antenna feed is evaluated. This could replace the power dividing network in large arrays.