antenna feed photo
would you please introduce me some methods to feed a spiral p(at)ch antenna. (I mean a patch in a spiral shape)
suppose I want to feed a two arms spiral p(at)ch which is placed on a square dielectric as a substrate. the arms begin in the center of square substrate and grow exponentialy around each other. beacause of curvature of arms, direct feeding by a microstrip line is not possible so any other idea?
Did you mean helix antenna?
No,
as you see in this picture I mean a two-arms spiral p(at)ch on a square substrate witch can be supplied from the centre but how ?
One feed method for spirals (I've seen it done for equiangular slot spirals) was developed by R.C. Hansen and is termed an "infinite balun". It basically consists of connecting the pin of a coaxial line to one side of the spiral and the shield of the coaxial line to the other side. The coaxial shield is typically soldered to the underside of one of the element arms to prevent the radiation pattern from being affected by the asymmetry of the feed (beam squint). See the link below for a photo of an infinite balun feed:
http://www.ece.uiuc.edu/pubs/antenna/slide03.html
Another feed technique better suited for planar technology is to couple energy to the feed using a transmission line and proximity coupling. Typically these antennas are used with a groundplane spaced a quarter-wavelength behind the spiral so that the energy is directed in only one direction. A microstrip trace is printed between the antenna and the groundplane. This couples energy to the antenna when it is below the feedpoint. The trace can extend past the feed into a radial stub termination (quarter-wavelength). A matching section can match the impedance of the t-line to the antenna input impedance. An example of this feed is found in the paper "Single Feed Proximity Coupled Circularly Polarized Microstrip Monofilar Archimedean Spiral Antenna Array" by Raul R. Ramirez and Nicolaos G. Alexopoulos.
In general, you should be able to find references spiral antenna feed approaches in the IEEE AP-S literature.
hey antennas321
i could not find any thing in
h**p://www.ece.uiuc.edu/pubs/antenna/slide03.html
it is incorrect link!
thank you very much
How to simulate it in HFSS?
This looks like just what I need, but the link has gone 404. Does anyone know where I can find the photo? In my case I need to feed a bowtie mechanically from one end.
Thanks