We deal with the following system of coupled asymmetric oscillators $$\begin{aligned} \left\{ \begin{array}{l} \ddot{x}_1+a_1x_1^+-b_1x^-_1+\phi _1(x_2)=p_1(t) \\ \ddot{x}_2+a_2\,x_2^+-b_2\,x^-_2+\phi _2(x_1)=p_2(t), \end{array} \right. \end{aligned}$$
x
¨
1
+
a
1
x
1
+
-
b
1
x
1
-
+
ϕ
1
(
x
2
)
=
p
1
(
t
)
x
¨
2
+
a
2
x
2
+
-
b
2
x
2
-
+
ϕ
2
(
x
1
)
=
p
2
(
t
)
,
where $$\phi _i: \mathbb {R} \rightarrow \mathbb {R}$$
ϕ
i
:
R
→
R
is locally Lipschitz continuous and bounded, $$p_i: \mathbb {R} \rightarrow \mathbb {R}$$
p
i
:
R
→
R
is continuous and $$2\pi $$
2
π
-periodic and the positive real numbers $$a_i, b_i$$
a
i
,
b
i
satisfy $$\begin{aligned} \dfrac{1}{\sqrt{a_i}}+\dfrac{1}{\sqrt{b_i}}=\dfrac{2}{n}, \quad \text{ for } \text{ some } n \in \mathbb {N}. \end{aligned}$$
1
a
i
+
1
b
i
=
2
n
,
for
some
n
∈
N
.
We define a suitable function $$L: \mathbb {T}^2 \rightarrow \mathbb {R}^2$$
L
:
T
2
→
R
2
, appearing as the higher-dimensional generalization of the well known resonance function used in the scalar setting, and we show how unbounded solutions to the system can be constructed whenever L has zeros with a special structure. The proof relies on a careful investigation of the dynamics of the associated (four-dimensional) Poincaré map, in action-angle coordinates.