# US 4,398,199 A · Circularly polarized microstrip line antenna

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- Number: US 4,398,199 A
- Document ID: US4398199A
- Status: Granted
- Kind: A
- Application number: 06/240,610
- Filed: 1981-03-05
- Granted: 1983-08-09
- Earliest claimed: 1980-03-10
- Inventors: Toshio Makimoto; Sadahiko Nishimura
- Web page: https://patentgrep.com/patent/US4398199A

## CPC

- H01Q 21/24: Combinations of antenna units polarised in different directions for transmitting or receiving circularly and elliptically polarised waves or waves linearly polarised in any direction {(circularly polarised patch antennas H01Q9/0428; circularly polarised horns H01Q13/0241; cross-polarised horns H01Q13/0258; polarisation converters H01Q15/242; cross-polarised rear feeds H01Q19/136; crossed polarisation dual antenna H01Q25/001)}
- H01Q 11/02: Non-resonant antennas, e.g. travelling-wave antenna (Yagi antennas H01Q19/30)
- H01Q 13/206: {Microstrip transmission line antennas}
- H01Q 21/065: {Patch antenna array}
- H01Q 21/068: {using parallel coplanar travelling wave or leaky wave aerial units (H01Q21/065 takes precedence)}
- H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72)

## Abstract

A circularly polarized microstrip line antenna for receiving or transmitting a signal of a particular wavelength includes a dielectric substrate having a ground plate provided on one surface thereof and having a microstrip line formed on another surface thereof. The microstrip line has an omega shaped fundamental portion composed of a loop portion and a pair of straight portions. The loop portion is one of either a regular polygon or a continuous closed curve having a length equal to the particular wavelength. The loop portion is symmetric about an axis which is on one of the surfaces of the substrate and is at right angles to the straight portions of the microstrip line.

## Claims

### Claim 1

A circularly polarized microstrip line antenna for receiving or transmitting a signal of a particular wavelength comprising:
a dielectric substrate having a ground plate provided on one surface thereof and having a microstrip line formed on another surface thereof;
wherein said microstrip line has an omega shaped fundamental portion composed of a loop portion and a pair of straight portions;
and wherein said loop portion is a regular polygon having a length .lambda.g equal to said particular wavelength;
and wherein said loop portion is symmetrical about an axis which is on one of said surfaces of said substrate and is at right angles to said straight portions of said microstrip line;
and wherein an angle .alpha. is defined by one of said pair of straight portions and a side of the polygon connected to said straight portion, said angle .alpha. being obtained by the equation: ##EQU5## where .theta..sub.m is the direction of a main beam of said antenna and .eta. is an effective wavelength reduction rate thereof;
and wherein a total length of said pair of straight portions d is obtained by the equation:
d=.lambda.g/(1-.eta. cos .theta..sub.m).

### Claim 2 (depends on 1)

A circularly polarized microstrip line antenna according to claim 1, wherein said loop portion is a square.

### Claim 3 (depends on 1)

A circularly polarized microstrip line antenna according to claim 1, wherein said loop portion is a hexagon.