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Carolina Windom Antenna

Sep 2nd 2015, 01:17

K2RAS

Joined: Sep 21st 2013, 03:42
Total Topics: 0
Total Posts: 0
I would appreciate some direction on my Carolina Windom antenna. My QTH consists of a Pixel amplified mag loop antenna for HF receiving. Transmitting has been done on a Carolina Windom and also a 55' random wire/counterpoise antenna on 80-6M.

I am perplexed that the random wire is 'deaf' across all the bands but transmits much better than the WIndom. The Carolina Windom's transmit performance is miserable but the receive performance is far better than the random wire. This comparison is true across all of the HF bands. How is it possible that the good transmit antenna is deaf on receive, and the good receive antenna cannot transmit well?

Since I mainly receive on the mag loop, I am considering removing the Windom and going back to the random wire antenna for transmitting, but want to make sure I am making the correct decision. Supposedly the Windom is a more sophisticated antenna than the simple random wire. The SWR levels are relatively similar across the two antennas. My choice of these two antennas is due to a HOA limitation on space.

Any direction is appreciated,
Ron, K2RAS
Sep 2nd 2015, 13:48

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
It is likely that the random wire is close to local noise sources, so it doesn't hear well. Close noise sources can couple inductively into wires--but only over very short distances.

The height is a big factor on how well an antenna transmits--at low heights, vertical wires, or vertical wires top loaded by horizontal wires, can be the most effective option when a counterpoise is available. In order for the horizontal portions of the Carolina Windom to be effective, they need to be about a half wavelength above ground. For short skip 80/40 less height, perhaps 40 ft, can be effective. But, on higher bands, like 10 and 15 meters, short skip is a very rarely occurs. And, when you do get E skip, DXers are often on 6M rather than 10 meters--as 6M DX contacts are considered "more valuable."

Zack Lau W1VT
ARRL Senior Lab Engineer
Sep 2nd 2015, 14:33

K2RAS

Joined: Sep 21st 2013, 03:42
Total Topics: 0
Total Posts: 0
Both antennas were about 30' above ground and positioned in the same location, not close to local noise in a rural environment. The antennas were as high as I can get them across some trees.

What do you think about removing the vertical radiator from the windom, making it an off-center fed as compared to the simple random wire at the same height?

Thanks, Ron
Sep 2nd 2015, 15:22

W1VT

Joined: Apr 4th 1998, 00:00
Total Topics: 0
Total Posts: 0
Experimenting with different antennas is a good way to find out what works best for you.

The vertical radiator of the Carolina Windom is established by installing an RF choke at the base of the vertical radiator/coax. This does have the advantage of blocking RFI from getting to the feedpoint of the antenna via the outside of the coax shield.

An effective technique, if you have an antenna that doesn't hear well, is to listen on a battery powered radio and shut off the main breaker to the home. About 50% of the time, when the ARRL gets an interference complaint, the source of interference turns out to be in the home of the ham making the complaint.

I've found that a half wave dipole can work really well with a 120 ft feedline that allows placement well away from houses. The low SWR of a resonant dipole allows low losses despite the long feedline. The better receive performance compensates for the slightly weaker transmit performance.

Zack Lau W1VT
ARRL Senior Lab Engineer

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