This is a picture of my EH ‘STAR’ antenna for 80 meters. It has two cylinders made from aluminium flashing 30 1/2” long, wrapped around 2” (2.375”) PVC pipe. Below the cylinders are two coils for matching and developing the EH field. There is a phasing coil between the cylinder. This antenna is described in the Demonstration #5 from Ted Hart.
Building the antenna is very easy and inexpensive. It has outperformed my other antennas (dipole made from two mobile whip antennas up 20 feet and a vertical w/o radials). The first test was when I checked into the weekly ARES Net (Statewide ARES Ne for South Texas), usually have to check in from an alternate net control due to a weak signal. The first night net control heard me the first time without any repeats. I next checked into the Southwest Traffic Net with the net control in Hot Springs Arkansas without any trouble. For a limited space antenna it appears to be doing a good job.
Materials:
2” PVC Sch. 40 Pipe – Home Depot / Lowe’s
Aluminium Roof Flashing (10” X 10’)Home Depot / Lowe’s
Short 2” PVC coupling (2)Home Depot / Lowe’s
Sheet Metal Screws #6 or #8 X 1/2”Home Depot / Lowe’s
2” PVC Cap Home Depot / Lowe’s
Brass Bolts/Nuts #6 X 3/4”Home Depot / Lowe’s
#14 Enamel Wire The Wireman (Internet)
Construction:
I drilled a small hole to start winding the Phasing Coil on one of the 2” PVC Coupling. The will also be used to place the wire down the middle of the cylinder, making sure the wire will reach the bottom of the Tuning Coil (~ 5 feet). Secure the winding using hot glue. I made each item (cylinders, coils) and then assembled them. It is easier to handle the smaller pieces than the large antenna.
Component Parts before Assembly
I cut a 24” piece of 2” PVC pipe to be used for winding the Tuning and Source Coils. I wound the Tuning Coil about 2 1/2” below the top of the pipe (when assembling the antenna this will be cut to maintain the dimensions of the antenna). Wind 34 turns on this PVC pipe (the Source Coil will be installed later). Add another two turns for tuning the antenna (it is easier to remove turns than to add them).
I cut two pieces aluminium flashing 8 1/2” X 30 1/2”. This is used to make the cylinders Cut 2 pieces of PVC pipe 36”. On one of the pieces mark the pipe 3/4” from the end (top of the cylinder). Bend the flashing around the pipe starting at the mark. This will be the top cylinder. Secure the flashing with sheet metal screws every 1 – 2”. Drill a hole on the bottom of the cylinder (long portion) and mount a 8 X 32 brass bolt 1/4” above the end of the cylinder. Mark the other PVC pipe 1 3/8” from the end. This will be the top of the bottom cylinder. Secure the flashing to the PVC pipe using sheet metal screws. Mount a 8 X 32 bolt 1/4” below the top of the bottom cylinder. Drill a small hole just above the bolt (this will be used to route the #14 enamel wire to the inside of the tube). Run the #14 enamel wire down the inside of the bottom tube. This wire should be as close to the PVC pipe as possible. Route the wire through the hole and mount to the bolt (remember to scrape the enamel off the wire before connecting to the bolt)
Install the top cylinder to the 2”PVC coupling with the Phasing Coil using PVC cement. The aluminium flashing should be against the coupling (we will cut the bottom cylinder PVC to get the correct spacing). Ensure that the end of the coil is lined up with the bolt. Scrape the enamel off the wire and install on the bolt. Put the bottom cylinder into the coupling for measurement. The two cylinders should be 1 diameter spacing ( 2 3/8”). After cutting the bottom cylinder to the correct dimensions, it is time to glue it into the coupling. The bolt on the bottom should be mounted 180 degrees from the bolt on the top cylinder. Measure the bottom end of the bottom cylinder and cut it off so the flashing is flush with the bottom coupling. Glue the coupling in place. Measure the pipe containing the tuning coil to the flashing for 1 diameter between the cylinder and the tuning coil. Cut the pipe and glue into place. Now we are ready to tune it.
Using the instructions in the Demonstration documents, tune the antenna. After the antenna is tuned, the source coil should be wound on the pipe and tuned per instructions.
Article by WB5CXC originally available at WB5CXC.com