## Antenna - Theory .com: The Antenna Site

antenna-theory.com :: View topic - Spiral Antennas
antenna-theory.com
Antenna Theory

Author Message

Joined: 03 Jan 2007
Posts: 197

 Posted: Sun Jul 17, 2011 10:11 pm    Post subject: Spiral Antennas I've added a page describing Spiral Antennas, their properties, design and implementation here: http://www.antenna-theory.com/antennas/travelling/spiral.php I've also added some information in audio visual format here at youtube: http://www.youtube.com/watch?v=JaJkZgiyTas The information on the two pages is somewhat overlapping; somewhat complimentary. Basically, the spiral antenna is one of the most fascinating antennas due to its wideband properties and circular polarization. Putting it on the website has been sorely missed up until now.

Joined: 03 Jan 2007
Posts: 197

 Posted: Sun Jul 17, 2011 10:13 pm    Post subject: Spiral Antennas and the Infinite Balun Spiral Antennas are also useful in describing the infinite balun, wherein you use the feeding coaxial cable as a part of the antenna itself. It is described on this page: http://www.antenna-theory.com/definitions/infinite.php
tensor20
Antenna Theory Regular

Joined: 12 Jul 2011
Posts: 18

 Posted: Tue Aug 02, 2011 2:38 pm    Post subject: current distribution Hello, the spiral antenna is a traveling wave antenna. Thanks for the posts. I will study them in detail. I have a trivial question: in the short dipole (L<
bigSteve
Antenna Wizard

Joined: 14 Mar 2009
Posts: 265

 Posted: Tue Aug 02, 2011 10:07 pm    Post subject: Current flows back and forth on the dipole. The charge is stored on the ends and changes in magnitude sign back and forth between the two ends. The flow of charge is current. A standing current wave still involves current flow. To understand this, note that a standing wave is caused by two sinusoids traveling in opposite directions to each other. So yes, charge must be moving if there is current, and if the current is changing then charge is moving. Hence, there is current flow.
florescent
Antenna-Theory.com Newbie

Joined: 13 Jun 2013
Posts: 1

 Posted: Thu Jun 13, 2013 5:20 am    Post subject: Different spiral antenna Dear Admin There is another type of spiral antennas as the link below http://commons.wikimedia.org/wiki/File:Archimedean_spiral.svg For this antenna design, one of the polarity locates at the end of the outer winding. The other polarity locates in the middle (it can be extended to the other side of the planar) Big difference between this antenna with what you introduce is the current flow between two adjacent turns; same direction for all turns for this type of antennas instead of opposite direction against adjacent turns for the introduced antenna type. This difference will make different electro-magnetic fields. Would you explain the difference in theory? Thank you
 Display posts from previous: All Posts1 Day7 Days2 Weeks1 Month3 Months6 Months1 Year Oldest FirstNewest First
 All times are GMT Page 1 of 1

 Jump to: Select a forum The Antenna Forum----------------Questions Related to Antenna TheoryNews
You cannot post new topics in this forum
You cannot reply to topics in this forum
You cannot edit your posts in this forum
You cannot delete your posts in this forum
You cannot vote in polls in this forum