Antenna - Theory .com: The Antenna Site

antenna-theory.com :: View topic - Planar Antenna Wavelength
antenna-theory.com
Antenna Theory

Author Message
Maxxpower
Antenna-Theory.com Newbie

Joined: 08 Sep 2015
Posts: 1
Location: Orlando, FL

 Posted: Tue Sep 08, 2015 1:59 pm    Post subject: Planar Antenna Wavelength Hi, When designing a planar (PCB trace) antenna the wavelength should be with regards to the Er of the material correct? Or do I use Er=1 for the wavelength? What does the width of my PCB trace do to the antenna properties? PCB antennas are not routed over ground planes so I guess I'm a little confused as to how the trace width and Er affect it. Thanks Ken
helix
Antenna Theory Regular

Joined: 29 Jan 2015
Posts: 64

 Posted: Thu Sep 17, 2015 1:19 am    Post subject: There is not a straightforward relationship between the effective wavelength (i.e., twice length at which a half-wave printed dipole becomes resonant) and the relative permittivity and thickness of the PCB. If you check out the NEC (old Fortran MoM code) theory manual, you can find some info on analytical corrections for thin/cylindrical wires insulated with a cylindrical material with relative permittivity greater than 1. How that quantitatively relates to a printed/PCB problem is beyond me. Sounds like you're kinda thinking about PCB trace width in the context of microstrip characteristic impedance. The thing is that antennas have antenna mode currents (also known as unbalanced currents) on them, and microstrip lines have transmisison line mode (also known as balanced currents) currents on them. These two types of currents serve very different purposes and behave very differently. On microstrip, increasing the trace width decreases the characteristic impedance. For a dipole, increasing the trace width lowers inductance, and tends to increase bandwidth. These two effects are related, but the way they're typically thought about is different. Search for "fat dipole" for an explanation.
 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