ARRL National Field Day 2011 (June 25–26) is rapidly approaching. Want to try a different antenna? One that no one else is bringing or probably ever heard of? How about building yourself a G7FEK nested 1/4 wavelength compact Marconi antenna that fits in a space that is 46' long and 24' high.
Summary of Features
- Compact size (46' long x 24' high)
- 50 ohm coax feed
- Multi-band operation for 80m to 10m
- Low angle of radiation (good for DX)
- Easy to build and set up
My friend KI4PMI and I always like to try something different each ARRL National Field Day. This year we selected the G7FEK as one of the antennas to be used during Field Day. The antenna turned out to be easy to build and after some experimentation we were able to adjust the 40 meter and 20 meter radiating elements for very low SWR operation using an AIM-4170C analyzer. The 80 meter band SWR curve was excellent without any adjustment. The other bands (17, 15, 12, 10, 6) indicated useable SWR curves but will require a good antenna tuner. We used a Palstar AT-500 manual antenna tuner to successfully tune these bands for maximum power transfer from the transceiver.
ANTENNA CONSTRUCTION TIPS:
Horizontal radiating elements. Make sure you cut the 7.1 MHz element long by at least 2' feet. It is a lot easier to trim than to add wire using butt splices. The 3.7 MHz horizontal element works fine at 38'.
Radials. You should be able to achieve good performance using (1) 66' radial positioned in the direction of the 3.7 MHz (38') horizontal element and (1) 33' radial positioned in the direction of the 7.1 MHz (8') horizontal element. The radials should be made of insulated wire and placed so they touch the earth.
20 meter add-on element. Be sure to include the 20 meter add-on element when you build the antenna. You will probably have to trim it a little bit to get the best SWR curve.
An interesting variant to the original G7FEK has been offered by G8JNJ. You may want to review his design before you build the antenna.
If you have limited space, you may want to consider using a G7FEK antenna as your primary antenna.
KI4PMI & NC4FB