Difference between revisions of "Antenna Performance Tests"

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−	In my present configuration, the ADC in Mercury will overload with the preamp on when connected to the active antenna .  To use the preamplifier for the upper HF bands, it will be necessary to add a low pass filter to reduce the AM broadcast contribution to the receiver.  You can see the 0-60 Mhz band scan from Mercury when using [http://openhpsdr.org/wiki/index.php?title=MacHPSDR MacHPSDR] in the next picture.	+	In my present configuration, the ADC in Mercury will overload with the preamp on when connected to the active antenna .  To use the preamplifier for the upper HF bands, it will be necessary to add a hi pass filter to reduce the AM broadcast contribution to the receiver.  You can see the 0-60 Mhz band scan from Mercury when using [http://openhpsdr.org/wiki/index.php?title=MacHPSDR MacHPSDR] in the next picture.
	[[Image:MacHPSDR.jpg|thumb|1000px| Screen shot of MacHPSDR by Jeremy KH6Z, showing the wide band 0-60 Mhz display]]		[[Image:MacHPSDR.jpg|thumb|1000px| Screen shot of MacHPSDR by Jeremy KH6Z, showing the wide band 0-60 Mhz display]]

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Revision as of 17:25, 9 April 2010

Active Antenna and Mercury

One of the great features of Mercury is its wide band capability. Most amateurs have antennas that are tuned to one amateur band. Often, these antennas do not perform well when used to listen on other frequencies. One type of antenna that is suited to wide band performance is an active antenna.

I purchased a Z1501D Active Antenna and Z1203A Active Antenna Coupler from Clifton Laboratories. These are both kits that are straightforward to put together and in my opinion are first class.

The active antenna at my station is using a 60 inch whip and the unit is mounted on a wooden fence post approximately 1.25 m above ground. I have a ground plate (1.2m long piece of electrical bus) buried in the earth about 0.6 m below ground.

Tests

The following is a screen shot of a wide band scan (0-20 Mhz.) of the output of the antenna coupler when connected to a Tektronics 495P Spectrum Analyzer.

This scan shows the AM broadcast band (centred at 1.0 Mhz, 200 Khz. per horizontal division) showing the strongest signals received at my QTH in the 0-30 Mhz spectrum. The strongest AM station is at 1220 Khz and is at -15 dbm at this snapshot. There is another strong station at 610 Khz and is approximately -19 dbm.

The second plot of the same spectrum was captured by KE5FX's excellent Spectrum Surveillance Program which connects to to my spectrum analyzer and controls it using the GPIB port.

In my present configuration, the ADC in Mercury will overload with the preamp on when connected to the active antenna . To use the preamplifier for the upper HF bands, it will be necessary to add a hi pass filter to reduce the AM broadcast contribution to the receiver. You can see the 0-60 Mhz band scan from Mercury when using MacHPSDR in the next picture.

by Rick VE3MM