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My most successful antenna

By Robert Marshall-Read, G4VGO
Flag and Pennant Antenna mail list, November 4, 2000

Here in the UK (G4VGO) and in Ireland (EI7IU) I have used both the flag and the pennant with very good results. Presently I have two pennants fed nose to nose (east/west) and use a DPDT relay to switch directions.
This has been the most successful so far and although not a beverage, it out shines the phased loops and other small aperture receive antennas I have tried over the years. It is indeed a pleasure to throw the switch and watch the EU noise curtain drop about 30 to 40 dB and the stateside signals pop out of the noise at 559. With Atlantic thunderstorms approaching from the west, VK is workable with the null toward the QRN.
The antennas are right up against a tall hedge, but the pattern seems to be uniform and symmetrical in spite of the undergrowth and limbs.

The transformers are wound on type 43 material as per the classical K6SE design, and the feedline is dropped vertically to the ground from the plastic box that holds the transformer and the relay. I use ferrite beads (lots of them) at the box, along the feedline to the ground, and on the feedline into the shack at about 5 metre intervals and get great f/b ratios and no noticeable skewing of the patterns. Careful winding techniques and a variable resistor as a termination were both used. I have a broadcast station high in the band directly to the west and only thirty miles away to use as the benchmark for testing. There is another station on the same frequency to the east on the continent so it gives me a chance to fine tune the terminations. During the day, the switch puts one or the other at S9 with the heterodyne inaudible. That is used as a test before every session to make sure the antennas haven't changed.
On topband I use the C & S preamp, but have also used the ICE single band preamp with good success. On 80 and 40 no preamp is needed and the antennas both show flat SWR from 1.6 to well above 7 MHz.

As an omni receive antenna I use a coax loop, tuned to 1835 kHz. There are nulls to each side (N/S) but as most signals are arriving above the angle of the nulls, it gives me a chance to listen 360 degrees, then to switch the pennants in the proper direction. Occasionally I will phase the co-ax loop and the pennants to give me a deep null to take care of a particular noise or QRM source such as a local contest station with a particularly dirty transmitter or QRO.
I have to say that my house is on a lot 30 by 130 metres and the structures make it hard to do an real experimenting. Topband is about all I operate so that makes it all a real challenge.

My next project is a three pennant array with stepping relay switching, but I haven't had the time to go beyond the paper stage yet, and the XYL still insists on using the back garden for the clothesline so it may stay on the drawing board.

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