Ultra wideband frequency dependent attenuator with constant group delay

An apparatus for providing a desired switchable time delay at a constant loss to an input signal, the apparatus comprising:

• a first time delay line providing a first time delay;
• a second time delay line including a hybrid microstrip transmission component which provides a second time delay shorter than said first time delay, and which has a physical length shorter than said first time delay line, and a frequency dependent loss matching a loss of said first time delay line with substantially constant group delay;
• and
• a switch for selecting one of said delay lines, depending on a desired time delay to be applied to said input signal, to thereby route said input signal through a selected one of said delay lines so as to achieve said desired time delay of said input signal.

A method for forming a compensated attenuator for providing a desired degree of loss and a desired degree of time delay to an input signal fed thereinto, said method comprising the steps of:

• forming a first delay line from a length of ordinary microstrip transmission line, said first delay line having a first loss characteristic;
• forming a second delay line from a length of engineered lossy microstrip transmission line having a second loss characteristic that is different than said first loss characteristic;
• and
• placing said first and second delay lines in series with one another to effectively form a single, continuous microstrip transmission line having said desired degree of loss and said desired degree of time delay with a substantially constant group delay.