Rf rejection filter

Claim 1

In a microwave RF rejection filter, a filter form supported in substantially uniformly spaced capacitively coupled relation to the surface of an electrically conductive material coextensive through the area of the filter form; said filter form including several open-ended stubs spaced in mutual capacitive and inductive cross coupled relation; electrical reference plane means interconnecting said several open-ended stubs; said electrical reference plane means being a section of conductive line extended to terminations at each end at a length beyond adjacent outer stubs that is short relative to RF signal wavelengths within the operational bandwidth for the filter, said stubs being substantially a quarter of an RF wavelength long in their extension from said electrical reference plane means to the stub outer open ends, filter form signal connective means; and with area of filter form middle stubbing varied from area of outer stubs for all filter form stubs to be substantially the same effective operational electrical length and attain substantially equal impedance and substantially equal propagation velocity in all of the stubs of the filter form, all of said stubs being of substantially equal length in extension from said electrical reference plane means to the stub outer open ends and with a middle stub being narrower than the width of individual outer stubs, said several stubs being in substantially uniformly spaced parallel relation with spacing between said stubs of approximately 0.1 RF signal wavelength.