Use of Narrower Reflection-Canceling Slots to Design Linearly Polarized Radial Line Slot Arrays With Improved Radiation Performance

In linearly polarized (LP) radial line slot arrays (RLSAs), reflection canceling slots (RCSs) are used in addition to the radiating slots (RSs) to reduce the return loss. The densely populated slotted RLSA apertures present the challenge of avoiding physical overlap between the RCSs and RSs. A solution to displace RCSs from their optimal position complicates the design and makes it less predictable. A design presented here addresses this issue using narrower RCSs on the same current-flow lines as their corresponding RSs. A high-gain LP RLSA antenna with diameter 12
$\lambda _0$
was designed, fabricated, and tested using the proposed strategy. The measured prototype demonstrated a wide matching bandwidth of 74.3%. The antenna achieved a maximum gain of 28.3 dBi at the operating frequency of 17 GHz, and a 3 dB gain bandwidth of 6.3%. At this frequency, it has an aperture efficiency of 51%, a total efficiency of 95.3% along with high cross-polar discrimination, which is more than 70 dB in the direction of the beam peak.