I. Theory
1. Basic Structure [Naver,
Kseo]
2. Applied structures
[www.microwave101.com]
- Combining two signals with
90-degree phase difference
- Divide a signal with two signals
with 90-degree phase difference
- Realizing a 180-degree hybrid
coupler with a quadrature hybrid coupler
II.
Applications
1. Power combining for power
amplifiers [www.rfcafe.com]
2. Single-balanced mixer
Figure: Quadrature hybrid coupler in
a single-balanced mixer [file.scirp.org]
Figure: PCB layout for a
quadrature-hybrid single-balanced mixer.
3. Circularly polarized antennas
Rahimian, "A novel circularly
polarized dielectricresonator antenna with
branch-line coupler and log-periodic balun", Int J Comm Eng, 7(1), 1-11, 2018.
Figure: Circularly polarized
dielectric resonator antenna fed by a quadrature hybrid coupler. Substrate: εr
= 4.4, tanδ
= 0.02, h = 0.787 mm, W × H = 75 × 75 mm, Quadrature hybrid coupler: Z1 = 175.2 Ω, Z2 = 95.1 Ω, Z3 = 118.4 Ω, Z4 = 62.9 Ω, Z0 = 50 Ω [Rahimian(2018)]
4. Monopulse
comparator
www.microwave101.com
III. Laboratory
Fig.
3.1 Standard configurations of a microstrip
quadrature hybrid coupler [Kseo]
Fig.
3.2 Modified quadrature hybrid coupler with input-output lines90-degree rotated
[WIPL-D, "High level miniaturization for quadrature hybrid directional
coupler"]
Substrate:
er = 4.3, tand = 0.02, h =
1.0 mm, t = 0.034 um
Input
and output line lengths: 1/8 wavelengths
Spacing
between substrate edge and the line edge: 10 mm
1.
For the structure in Fig. 3.2, find the line width and lengths for Z0 = 50 Ω and f = 1 GHz.
2.
Make a structure for simulation.
3.
Calculate scattering parameters.
Port number: Input = 1, Isolation = 2,
Output = 3, 4
4.
Plot the results.
Plot 1: Magnitude in dB of S31 and S41.
Frequency 0.7-1.3 GHz, Magnitude -10 dB to 0 dB
Plot 2: Magnitude in dB of S11 and S21.
Frequency 0.7-1.3 GHz, Magnitude -70 dB to 0 dB
Plot 3: Amplitude balance = |S31| (dB) −
|S41| (dB)
Plot 4: Phase balance = arg(S31)
(deg) −arg(S41) (deg)
5.
Find the bandwidth based on your own criteria.