Compact 2 x 2 Coupled Double Loop GPS Antenna Array Loaded With Broadside Coupled Split Ring Resonators

The design and nulling capability of a compact 2 × 2 dual-band coupled double loop (CDL) GPS antenna array loaded with broadside coupled split ring resonators (BC-SRR) are presented. The high level of L₂ band mutual coupling is reduced by utilizing -negative (MNG) BC-SRR metamaterial within the array volume. This metamaterial loading is possible due to the small L₂ band electrical size (λ_o / 8.5 × λ_o / 8.5) of the CDL antenna elements. Different than the existing work on coupling reduction of linearly polarized antenna arrays, mutual coupling mechanism within the circularly polarized GPS array is considered and MNG metamaterials are shown to reduce the mutual coupling if they are placed between the antennas in a particular alignment. Specifically, a 2 × 2 array with inter-element spacing is designed to be loaded with BC-SRRs and experimentally verified to exhibit a 10 dB L₂ band mutual coupling reduction. Through simulations and experiments, it is also demonstrated that the reduction in L₂ band mutual coupling improves the L₂ band array nulling capability in terms of accuracy and null depth without affecting the already well-behaved L₁ band performance. The presented array has an overall footprint size 4.3" × 4.3" of and can be potentially miniaturized further for different inter-element spacing.