Leaky-wave based interpretation of the radiation from holographic surfaces

3-D-Printed 96 GHz Bull’s-Eye Antenna With Off-Axis Beaming

“…Closer in time, the modal properties of the leaky and surface waves propagating along the metallic gratings on the GDS were scrupulously described in [39]. While clarifying the physical connection between the optical concept of holography and the leaky wave mechanism, a double period strip grating enabling off-broadside beaming was reported in 2007 [40]. Likewise in [41], [42] a thorough analysis was done about the beam sweeping capability of asymmetric structures based on subwavelength slits perforated in slabs surrounded by gratings at both sides.…”

A holographic antenna approach to improve the surface wave efficiency and gain of a microstrip patch

“…(2). Accordingly, the simplest realization of the SW based holographic antennas (or, SW-LWAs) involves a single continuous (or, pseudo-continuous) metallic ring per period [4], [5], [6]. However, in the range of operation of the microstrip patch, λ T M0 ≈ λ 0 , and consequently, p ≈ λ 0 , which is close to the grating lobe condition.…”

“…In the specific case of the SW based holographic antenna, the pattern of the holographic surface is determined by the interference pattern of the SW on the grounded slab and the incoming plane wave from the direction of the intended maximum radiation [6]. Since we are concerned with maximum radiation in the broadside direction and the SW is assumed to be cylindrical, the interference pattern on the grounded slab takes the form of concentric rings centered at x = y = 0 with a periodic distance p ≈ λ T M0 , which is consistent with the (H…”

“…However, in the opposite end, there exists a class of SW based leaky-wave antennas (SW-LWA) where the SW is desirable such that its excitation should be maximized. In such antennas, high directional gain can be achieved at the cost of increased area [4], [5], [6]. The relationship between SW-LWAs and holographic surfaces were explained in [6], and as a result, the initial design of a SW-LWA can be approached in an intuitive manner using the holographic concept.…”

“…In such antennas, high directional gain can be achieved at the cost of increased area [4], [5], [6]. The relationship between SW-LWAs and holographic surfaces were explained in [6], and as a result, the initial design of a SW-LWA can be approached in an intuitive manner using the holographic concept. In many designs, however, the SW-LWA operate at SW wavelengths which are considerably shorter than the freespace wavelength (e.g., λ T M0 /λ 0 ≈ 0.5 − 0.6 in [4], [5]), which is beyond the typical range of operation of a microstrip patch (where λ T M0 /λ 0 ≈ 1).…”