We decided to start the construction of an EMC measurement antenna. So the choice was a Log Periodic antenna - it's basic characteristics are: 
 
- Frequency range: 200Mhz to 3Ghz 
- 23 Elements 
- Tau = 0.86 
- Sigma = 0.065 
- Psi (separation angle) ~ 4 degrees 
- Gain ~ 6.5dB 
 
Construction materials are copper-plated brass rectangle box for the feeders, and brass round stock (tube and solid) for the dipole elements. We'll be going down to MS&T - Missouri University of Science and Technology - (formerly UMR) for testing to determine the Antenna Factor curve. 
 
Pics (Corresponding images are below titles) ... 
 
Milling the holes for the dipole elements - 

 
Finished holes for the dipole elements - 

 
Final raw materials ready for final assembly - 

 
Assembly starting at the high frequency end - 

 
Finished antenna - 
 
 
Still need to add mounting sections and the coax/N-connector. 
 
Here's a modified Excel spreadsheet we used for developing some of the basic parameters: LOGPERIO_1.xls.zip