Article
On the Use of Ridge Gap Waveguide Technology for the Design
of Transverse Stub Resonant Antenna Arrays
Javier Benavides-Vazquez
1,2,
* , Jose-Luis Vazquez-Roy
2
and Eva Rajo-Iglesias
2
Citation: Benavides-Vazquez, J.;
Vazquez-Roy, J.L.; Rajo-Iglesias, E.
On the Use of Ridge Gap Waveguide
Technology for the Design of
Transverse Stub Resonant Antenna
Arrays. Sensors 2021, 21, 6590.
https://doi.org/10.3390/s21196590
Academic Editors: Ángela María
Coves Soler and Antonio Lázaro
Received: 31 August 2021
Accepted: 30 September 2021
Published: 2 October 2021
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4.0/).
1
Indra Sistemas, S.A., 28850 Torrejon de Ardoz, Spain
2
Signal Theory and Communications Department, Universidad Carlos III de Madrid, 28911 Leganes, Spain;
jvazquez@tsc.uc3m.es (J.-L.V.-R.); eva@tsc.uc3m.es (E.R.-I.)
* Correspondence: javier.benavides@uc3m.es
Abstract:
This paper presents some considerations on the design of a novel antenna consisting of
the combination of a transverse stubs (TS) array excited by Ridge Gap Waveguides (RGWs), as
well as a discussion of the experimental results obtained from a prototype that was manufactured
and measured. A combination of Continuous Transverse Stubs (CTSs) is used as the starting point.
Subsequently, the CTSs are modified to include some metallic blockers that split each CTS into a
combination (array) of shorter TSs. This is performed in order to excite each individual TS column
using a different RGW; thus, ensuring a close to uniform field distribution in the transverse plane of
the TS arrays. Hence, the directivity of the antenna is increased. As a series-feed configuration is
considered, the antenna keeps a resonant behaviour, having a narrow-band response. A Corporate
Feeding Network (CFN) using the aforementioned RGW technology placed in the same layer as
the rest of the antenna is included in the design. The radiating area of the antenna is, finally,
5.88
λ
0
×
7.12
λ
0
with a simulated peak gain of 26.2 dBi and a Side Lobe Level (SLL) below
−
13 dB.
A prototype is manufactured and tested. The simulated and measured radiation patterns maintain
similar shapes to those of the simulations, with very similar angular widths in both main planes,
although the frequency corresponding to the highest directivity changes to 31.8 GHz. A matching
bandwidth of 517 MHz and a gain of 24.5 is, finally, achieved at that frequency.
Keywords:
continuous transverse stub (CTS); ridge gag waveguide (RGW); ka-band; resonant antenna
1. Introduction
Nowadays, with the trend of moving up in frequency communication services, it
is common to see antennas working at very high-frequency bands. Moreover, antenna
integration has become a key issue for the radio-frequency community.
Some applications, such as on-the-move SATCOM communications, are following the
aforementioned trends, besides many others. Consequently, very compact designs are needed
in order to integrate these antennas above different structures (aircraft, ground vehicles, etc.).
As for any other satellite application, the gain of an antenna is a key performance indicator.
In this context, Continuous Transverse Stub (CTS) arrays appear as interesting can-
didates for the antenna designer. With very high directivity values, compact designs and
high aperture efficiencies, these elements have demonstrated several benefits over other
antenna designs (e.g., slotted waveguides or microstrip patches) [1–3].
In their series-feed resonant form, i.e., terminating the antenna with a short circuit [
4
],
narrowband responses are expected. For those cases in which a true-time delay implemen-
tation [
5
] is selected, e.g., [
6
], wider bandwidths can be achieved at the cost of increasing
the design and manufacturing complexity by using a parallel feed strategy.
Considering a resonant design where the radiating elements are located in the posi-
tions of the maxima of a standing wave, a
λ
g
spacing between consecutive CTS radiating
elements is needed. For this reason, a low-loss dielectric is used in the host waveguide to
avoid grating lobes in the resulting radiation pattern by making
λ
g
< λ
0
. On the contrary,
Sensors 2021, 21, 6590. https://doi.org/10.3390/s21196590 https://www.mdpi.com/journal/sensors
