US 12,272,874 B2
Sub-GHZ circularly polarized UWB MIMO antenna
Rifaqat Hussain, Dhahran (SA)
Assigned to KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS, Dhahran (SA)
Filed by KING FAHD UNIVERSITY OF PETROLEUM AND MINERALS, Dhahran (SA)
Filed on May 9, 2023, as Appl. No. 18/314,449.
Prior Publication US 2024/0380115 A1, Nov. 14, 2024
Int. Cl. H01Q 13/10 (2006.01); H01Q 1/28 (2006.01); H01Q 13/02 (2006.01); H01Q 21/06 (2006.01); H01Q 21/24 (2006.01); H04B 7/0413 (2017.01)
CPC H01Q 13/106 (2013.01) [H01Q 1/288 (2013.01); H01Q 13/0241 (2013.01); H01Q 21/24 (2013.01); H04B 7/0413 (2013.01)] 20 Claims
OG exemplary drawing
 
1. A dual port, slot-based multiple-input-multiple-output (MIMO) antenna for cubic shaped satellites (CubeSat), comprising:
a dielectric circuit board having a surface dimension of about 100 mm in length and about 100 mm in width, a top side, a bottom side, a first edge opposite a second edge, a third edge opposite a fourth edge, a first central axis extending from the first edge to the second edge, and a second central axis extending from the third edge to the fourth edge;
a metallic layer configured to cover the top side of the dielectric circuit board;
a first pentagonal loop slot line and a second pentagonal loop slot line etched into the metallic layer on the top side of the dielectric circuit board, wherein the second pentagonal loop slot line is a mirror image of the first pentagonal loop slot line across the second central axis, wherein each pentagonal loop slot line is configured to have:
an apex coincident with the first central axis;
a first leg having a first end at the apex, wherein the first leg extends from the apex towards the third edge at a first angle;
a second leg having a first end connected to the first leg at the apex, wherein the second leg extends from the apex towards the fourth edge at an angle equal to a negative of the first angle;
a third leg having a first end connected to a second end of the first leg, wherein the third leg extends parallel to the third edge and towards the second central axis;
a fourth leg having a first end connected to a second end of the second leg, wherein the fourth leg extends parallel to the fourth edge and towards the second central axis;
a fifth leg which extends between a second end of the third leg and a second end of the fourth leg, the fifth leg configured with a gap, wherein the gap is bisected by the central axis; and
a varactor diode connected across the gap to the metallic layer on either side of the gap;
a first tapered feed horn located on the bottom side, wherein the first tapered feed horn is connected to a first feedline which extends from the third edge towards the first central axis, wherein an opening of the first tapered feed horn extends towards the gap in the fifth leg of the first pentagonal loop slot line;
a second tapered feed horn located on the bottom side, wherein the second tapered feed horn is connected to a second feedline which extends from the fourth edge towards the first central axis, wherein an opening of the second tapered feed horn extends towards the gap in the fifth leg of the first pentagonal loop slot line;
a third tapered feed horn located on the bottom side, wherein the third tapered feed horn is connected to a third feedline which extends from the third edge towards the first central axis, wherein an opening of the third tapered feed horn extends towards the gap in the fifth leg of the second pentagonal loop slot line;
a fourth tapered feed horn located on bottom side, wherein the fourth tapered feed horn is connected to a fourth feedline which extends from the fourth edge towards the first central axis, wherein an opening of the fourth tapered feed horn extends towards the gap in the fifth leg of the second pentagonal loop slot line;
a first adjustable voltage source connected to the varactor diode of the first pentagonal loop slot line, wherein a change in a voltage of the first adjustable voltage source is configured to tune a resonant frequency of the first pentagonal loop slot line of the dual port, slot-based MIMO antenna; and
a second adjustable voltage source connected to the varactor diode of the second pentagonal loop slot line, wherein a change in a voltage of the second adjustable voltage source is configured to tune a resonant frequency of the second pentagonal loop slot line of the dual port, slot-based MIMO antenna,
wherein the dual port, slot-based MIMO antenna is configured to resonate with circular polarization at a resonant frequency in an ultra-high frequency sub-GHz range of about 578 MHz to about 929 MHz when an input signal is applied to each feedline.