Friday, 6 April 2012

Comparing antennas with RBN

In my last posting about Reverse Beacon Network i suggested that those reverse becons could be used for antenna testing. Today I got a good reason to try it myself: I am preparing for a domestic contest on 80/40m bands. I have two antennas suitable for 40m:
  • 80m delta loop, with a little bit odd dimensions: The "north" corner is up almost 30 meters and the "south" corner is only 10m up. The antenna is fed at the bottom, near ground, with a 1:4 balun. Pictures here.
  • 1/4 wave GP, up 12m, in a tree. Solid copper pipe with three radials. Picture here.
So, which antenna is better for QSOs here in Finland? The theory suggests that verticals are good for DX and my loop antenna should have a high lobe, making it an antenna suitable for domestic QSOs.

I started calling CQ on 7.024 MHz using the gp antenna first. No-one answered me, but after a couple of CQs, the Reverse Beacon Network gave me a list of stations who heard me. I copied it to Excel, added locator, distance and bearing data (there are tools for that on the net, eg:, formatted the table to look nicer :) and copied here:

UA4NE7022.110 dBLO48UO1224z 06 Apr144486
OH8WW7022.129 dBKP24HP1224z 06 Apr4872
RZ3DVP7022.010 dBKO85OU1224z 06 Apr906117
LA5EKA7022.015 dBJO59EK1224z 06 Apr777269
ES5PC7022.014 dBKO38HJ1224z 06 Apr149146
DJ9IE7022.115 dBJO31VN1224z 06 Apr1402234
US0KW7022.015 dBKO30OO1224z 06 Apr1091169
OH6BG7022.027 dBKP03SD1224z 06 Apr349337
RN3A7022.016 dBKO85NU1224z 06 Apr902117
SK3W7022.018 dBJP80JH1224z 06 Apr409274
DR1A7022.09 dBJO31CQ1224z 06 Apr1463237
OL5Q7022.011 dBJO60VI1224z 06 Apr1281215
DL1EMY7022.016 dBJO31GE1224z 06 Apr1489235
Avg dist (km):934,54
OK, then the same test with the loop antenna.  The frequency has to be changed a bit, so that the stations make a new measure. The results are here:
Call QRG dB Loc Time Km Bearing
OH8WW 7024.0 33 dB KP24HP 1226z 06 Apr 487 2
US0KW 7024.0 21 dB KO30OO 1225z 06 Apr 1091 169
RN3A 7024.0 10 dB KO85NU 1225z 06 Apr 902 117
OH6BG 7024.0 38 dB KP03SD 1225z 06 Apr 349 337
SK3W 7024.0 18 dB JP80JH 1225z 06 Apr 409 274
RZ3DVP 7024.0 15 dB KO85OU 1225z 06 Apr 906 117
LA5EKA 7024.0 12 dB JO59EK 1225z 06 Apr 777 269
ES5PC 7024.0 21 dB KO38HJ 1225z 06 Apr 149 146
Avg dist (km): 633,75
Interesting stuff was found in the tables:
  • Local stations seem to be stronger with the loop antenna. 
  • The gp was heard by many more long-distance stations
This is according to the theory, right? The GP seems to cover europe better than the loop, but I am not 100% sure about all directions yet since the bearings are not analysed. 

[Edited 13.April 2012:] Later I found the station map from the site...very much like the pskreporter map, very useful!

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