# Planar Printed Structures Based on Matryoshka Geometries: A Review

## TL;DR

This paper reviews planar printed structures inspired by Matryoshka doll geometries for microwave applications like antennas and sensors.

## Contribution

The novelty lies in combining Matryoshka-like nesting with planar printing for miniaturized, multi-functional microwave devices.

## Key findings

- Matryoshka geometries enable miniaturized and wideband microwave structures.
- Both metal and slot structures show potential for low-cost, single-layer applications.
- The review highlights physical insights and future research directions for these designs.

## Abstract

A review on planar printed structures that are based on Matryoshka-like geometries is presented. These structures use the well-known principle of Matryoshka dolls that are successively nested inside each other. The well-known advantages of the planar printed technology and of the meandered nested Matryoshka geometries are combined to generate miniaturized, multi-resonance, and/or wideband configurations. Both metal and complementary slot structures are considered. Closed and open configurations were analyzed. The working principles were explored in order to obtain physical insight into their behavior. Low-cost and single-layer applications as frequency-selective surfaces, filters, antennas, and sensors, in the microwave frequency region, were reviewed. Potential future research perspectives and new applications are then discussed.