# US 5,349,365 A · Quadrifilar helix antenna

> Agents: this data is available as JSON from the patentgrep API and MCP server — see https://patentgrep.com/llms.txt

- Number: US 5,349,365 A
- Document ID: US5349365A
- Status: Granted
- Kind: A
- Application number: 07/779,895
- Filed: 1991-10-21
- Granted: 1994-09-20
- Earliest claimed: 1991-10-21
- Inventors: Steven G. Ow; Peter J. Connolly
- Web page: https://patentgrep.com/patent/US5349365A

## CPC

- H01Q 11/08: Helical antennas
- H01Q: ANTENNAS, i.e. RADIO AERIALS (radiators or antennas for microwave heating H05B6/72)

## Abstract

An improved helix antenna including a single unitary antenna having plural radiating elements extending radially from a common junction. A microstrip balun is connected to the plural antenna elements at the common junction. In a particular embodiment, the antenna includes four radiating elements arranged in a helical pattern and mounted such that a longitudinal axis extending through the axial center of the antenna is coincident with a longitudinal axis of the microstrip balun. One or more of the radiating elements includes a semi-circular loop to create phase relationships necessary for a circularly polarized beam pattern. The microstrip balun includes a transmission line and a ground plane on opposite sides of a dielectric substrate. The transmission line and the ground plane are tapered for impedance matching between the input and the output thereof.

## Claims

### Claim 1

An improved quadrifilar helix antenna comprising:
a unitary antenna having at least two radiating elements extending radially from a common junction and
a microstrip balun connected to said plural antenna elements at said common junction,
wherein said radiating elements are joined at distal ends thereof, arranged in a helical pattern, and mounted such that a longitudinal axis extending through the axial center of the antenna is coincident with a longitudinal axis of said microstrip balun and each of said antenna elements includes a tab at said distal end thereof adapted to engage a slot in said microstrip balun.

### Claim 2 (depends on 1)

The invention of claim 1 wherein one or more of said antenna elements includes a semi-circular loop extending the length of said antenna element.

### Claim 3 (depends on 1)

The invention of claim 1 wherein said balun includes a microstrip transmission line and a ground plane on opposite sides of a dielectric substrate.

### Claim 4 (depends on 3)

The invention of claim 3 wherein said transmission line is tapered.