A slot design for uniform aperture field distribution in single-layered radial line slot antennas

Design of mm-Wave RLSAs with Lossy Waveguides by Slot Coupling Control Techniques

“…The maximum coupling factor α max is properly chosen as not to disturb the rotational symmetry of the inner field of RLSA [18]. It can be observed that, the maximum gain coupling (15) is stronger than no loss design coupling (4) and maximum directivity coupling (16), and all three curves are converged to a limitation α max while the slots position approaches the antenna rim. On the other hand, a maximum directivity coupling (16) is the weakest among these three.…”

“…Figure 8 clarifies the advantage of the maximum gain coupling (15) over the no loss design coupling (4) and the maximum directivity coupling (16), by characterizing the gain of a 400 mm diameter RLSA as functions of the loss factor. Two observations can be drawn from this figure: -the maximum directivity design suffers from the dielectric losses most seriously; -the maximum gain design is indispensable to minimize the degradation caused by the dielectric losses, especially in case of very lossy dielectric materials and/or very large apertures.…”

“…For example, in the practical design of Hayabusa 2 antenna [13], the residual power t is estimated to be less than 1%. For an RLSA with small aperture, the limitation of the coupling factor results in an considerably large residual power t at the termination (5∼15%), and it should be taken into account in the process of arriving at the solution for the coupling factor distribution α r (ρ) [16].…”

“…Takahashi et al [16]- [18] have established a procedure to realize uniform amplitude and phase of the field radiated from the slots, which could assure high antenna gain if the dielectric loss was negligible. The key techniques of this procedure are: -the slot coupling distribution to control the amplitude of the electrical field radiated from slots; -the slot positioning to have an in-phase excitation and radiation.…”

A Spiral Shaped Slot as a Broad-Band Slotted Waveguide Antenna

“…In this case, the spiral slots act similar to rectangular slots cut on the broad wall of the waveguide and they need to be studied as elements of a SWA array rather than standalone traditional spiral antennas. Spiral configuration of rectangular slots [13,14] cannot be used for SWASS where hat stiffeners in the airplane skin operate as rectangular waveguides not radial waveguides. A continuous spiral slot has not yet been used as an element of rectangular SWA arrays.…”