Paper-Thin Membrane Aperture-Coupled L-Band Antennas

A microstrip line on very thin membrane substrate (0.05 mm) is slot-coupled through a thick air substrate (12.7 mm) to excite an L-band radiating patch element. A breadboard unit achieved a relatively wide bandwidth of 100 MHz (8%). Very narrow coupling slot is used with aspect ratio of 160 (conventional slot aspect ratio is between 10 to 30). This new feed design makes the thin-membrane or inflatable array antenna technology more practical. It reduces the number of thin-membrane layers required for a dual-pol wide-band inflatable array from three layers in a previous design to two layers. In addition, this technology allows the thin-membrane array antenna elements to be readily integrated with thin-membrane-mounted transmit/receive (T/R) modules. Calculation shows that, without the patch, the microstrip line and slot combination can also radiate as a paper-thin (0.05 mm) radiator at the L-band frequencies.