PocketPC ham radio apps, links, DXPedition Map, and more.
 

   

 

sitemap



PropagationStats

Add PropagationStats to your site.

 

 

 

 

 

 

 

 

 

 

 

Inverted Ls for 160 and 80 meters

Pros and Cons of the Dual Band Inverted L Antenna

A dual band/single antenna approach introduces complexity by adding a trap. In fact, some have warned against attempting the antenna due to the trap alone.  Having a single wire to cover the lowbands is tempting, but may not be worth the increase in complexity and probability of failure.

 

Evolution of the dual band 160/80 meter inverted L using MMANA

The popular inverted L seems to be a good choice for ease of installation, low cost, and design flexibility.

Having driven my ham radio budget into the red with the tower project, I have resorted to using a freeware antenna modeling program: MMANA    The modeling package is based on MININEC which has a number of limitations.

I started with a simple base fed, quarter wave, inverted L for 160 meters.  Wanting to make this a dual band antenna, I decided to put a trap at the top of the vertical section. Given the lack of tall supports for the horizontal wire, I am forced to have a sloped L.  The resulting design is a vertical wire parallel to my tower (hopefully about 3 ft away), 18.5m up to the trap and 19m sloping down.

MMANA 160/80 Meter Inverted L Design N0HR

The feedpoint is a 300 pF series cap an UNUN to match the low impedance. The trap in the LC is at 2.9 MHz and consists of a 25.1 ÁH inductor and 120 pF cap.

MMANA setup inv L

 

Modeled Performance and SWR Plots: 80 meters

80 meter performance Inverted L

Gain

 

 

 

 

Modeled Performance and SWR Plots: 160 meters

160 meter SWR inverted L plot

160 meter inverted L gain plot

 

 



   
 

ę  2008 NěHR - All rights reserved