Guy, Thank you for the info! I'll read it over. Spacing is definitely important when antennas are side by side. What about flags in the same plane? For example, Flag #1 is oriented N/S, but is terminated on the north such that the lobe is to the south. Not too far away (but north of Flag #1) is Flag #2 also pointed N/S with its termination on the south end making its receive lobe to the north. Two cardioids, 2 opposite directions in the same plane. If these antennas are phased/mixed together "appropriately", is the resulting pattern a narrow figure-8?
Just a thought :-) 73, Chris -----Original Message----- From: [email protected] [mailto:[email protected]]on Behalf Of Guy Atkins Sent: Wednesday, January 28, 2009 4:10 PM To: [email protected] Subject: Re: [IRCA] ALA 100 Hi Chris, It wouldn't quite fit in your back yard, but an intriguing design is the Phased Flag Array as designed and described by Dallas Lankford (see the Kongsfjord.no DX site and look in the "Dallas Files" section). He and I have been discussing this antenna quite a bit recently. If the EZNEC plots are close to real-world performance it should outperform my Wellbrook Phased Array in terms of rearward nulling. I'm considering building Dallas' design for use on coastal DXpeditions. This antenna, with its broad forward lobe but also relatively broad null on the backside would be well suited for unattended use with a recording SDR like Perseus or the RFSpace units. This single antenna could receive stations from a range of azimuth bearings in the desired direction while reducing the level of many stations "behind" the receiver, and not need any knob twiddling once set up correctly. The Wellbrook Phased Array is similar but the phased flags definitely show a better pattern for nulling stations in what Dallas calls the "null aperature". Dallas believes that the 100 ft. spacing between the flags is the minimum that will successfully cover the entire band, so unfortunately it can't fit into a 60 ft. backyard without low band attenuation of signals. I wonder if a longer length of delay line could compensate for a < 100 ft. spacing? Dallas has also done computer modeling on a 4-flag array, with of course greater complexity in parts, cost, and required real estate. The details are shown at the end of his phased flags article. Regarding the ALA100, someone asked about a photo of the control box (interface). There is a picture of the box (white, with black label) on my blog posting here: http://perseus-sdr.blogspot.com/2006/09/in-shadow-of-mt-rainier-dxing-with.h tml The ALA100 box is just to the left of the smaller black box (PA0RDT mini-whip interface) and the two gell cell batteries in the second picture. 73, Guy Atkins Puyallup, WA www.perseus-sdr.blogspot.com _______________________________________________ IRCA mailing list [email protected] http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: [email protected] _______________________________________________ IRCA mailing list [email protected] http://montreal.kotalampi.com/mailman/listinfo/irca Opinions expressed in messages on this mailing list are those of the original contributors and do not necessarily reflect the opinion of the IRCA, its editors, publishing staff, or officers For more information: http://www.ircaonline.org To Post a message: [email protected]
