- - The Quad
Helix Array - -
This antenna can be scaled for use on 902 -
Details for the 33 CM band and for other
frequencies are below.
This design is
from an article by W6UQH in the August 1963 QST.
The description above is from the 1967 ARRL Handbook.
The information in the following
table is based on recommendations for helix design in the RSGB VHF/UHF
Manual, 4th edition. The axial-mode helix is quite broad-band and
relatively non-critical in its dimensions. Therefore the
frequencies calculated are for the center of each band. For these
bands the helix conductor can be 3 - 6 mm diameter (1/8 - 1/4 inch)
material. Copper wire or tubing is recommended, and connections
can then be readily soldered. In the quad array shown above, the lines from the
helix feedpoints to the common feed point for the coaxial line
must all be of the same length.
If designed for 1100 MHz, the
array should work well for both the 902-928 and 1240-1300 MHz bands,
IF you do not introduce some frequency-specific element in your design,
such as a 'quarter-wavelength matching section in the feedline'.
Documentation for the helical antenna indicates that it is capable of covering to
plus and minus 25% of the design center frequency.
||Wavelength (L) cm
||82 X 82
||68 X 68
||59 X 59
Return to the
902 Antennas Page.