Packaging of microstrip circuits using bed of springs to suppress cavity modes - A replacement for bed of nails

The bed of nails has been demonstrated to be very useful in the design of new confined gap waveguide appearing between parallel metal plates with texture, as well as for removing cavity modes in microstrip circuit packages. As the bed of nails is bulky at low frequencies due to the required height of the nails, a new version of this periodic structure is proposed herein, based on helices instead of nails. Thus, the bed of nails is replaced by a bed of springs. The bed of springs is much more compact for use at low frequencies, and its bandwidth turns out to be similar. Thus, the new spring mattress approach is more comfortable than the Fakirs bed of nails at low frequencies.