Design and construction of quadrifilar helicoidal antennas

One of the two QFH antennas on NOAA-17 (Photo courtesy and (c) Lockheed Martin

The quadrifilar helicoidal antenna - quite a mouthful - is easy to construct (even though it does look complicated), and the results are excellent. In contrast with the omnipresent turnstile antenna (two crossed dipoles with a reflector) the circularity is almost perfect in any direction. I've also received quite a few reports from people who built the antenna using the data from this page, who were very satisfied. In it's original form, the relation between diameter and height is 0.44, but decreasing this relation slightly, a still better coverage of for satellites near the horizon is obtained. In literature and on the web, extreme versions can be found. If the left column of this page (under 'Pictures') are links to pictures of several versions built by me and sent to me by several happy readers. The first link shows images generated by POV-ray.

Other pages on this antenna (local)

Link	Description
Photos	Computer generated images of the antenna
Photos 1	Images of the coax cable version of the antenna
Photos 2	Images of the copper tubing version of the antenna
Ivan 137MHz	Images of Ivan's 137 Mhz version
ON7EQ, 2m	Images of the 145 MHz, copper tubing version of ON7EQ
ON7EQ, 70cm	Images of the 435 MHz, copper tubing version of ON7EQ
Balthazar	Images of Balthazar's version
Nev G3LMO	Nev's version of the antenna, with an separate balun.
Antena DNA	Portable construction from Ekkehard (137 MHz)
Vaisala GPS	The Vaisala beacon's GPS front-end uses a QFH too, at 1700 MHz
Calculator	On-line Javascript calculator to determine antenna dimensions

Bibliography on quadrifilar antennas

The ARRL Antenna Handbook

The American Radio Relay League

(Information at Amazon.com)

A Quadrifilar Helix Antenna for 137 MHz

De George Goodroe, KF4CPJ. An extremely narrow version of the QFH

Paul's Weather Satellite and Waffle Page

from Paul Hayes. Page is a bit overloaded with Flash, etc., but has some interesting files on QFH construction

Personal pages of PA0ROJ

Partly in Dutch, partly in English - Follow the link to 'Weather Satellites'

Simplified astronomy (German)

Astronomy with simple tools. This is the page of Heiko Mayer who helped my translate this page into German.

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