[Elecraft] searching for post by Wayne n6kr about counterpoise

[Robert Cunnings]

Times change.

In recent years vertically polarized man-made electrical noise has been a 
growing problem. I was forced to use a dedicated receive antenna to 
mitigate severe local noise problems (switching power supplies, plasma TVs 
etc.) from my surrounding neighbors. Because the only practical transmit 
antenna option was a vertical (little space), I had to give up on it as a 
receiving antenna. After some experimentation, I settled on what is 
essentially a folded dipole antenna cut for 40m, which is very close to 
the ground. It's about 60 ft long and the wire spacing is about 4 ft, with 
the lower wire only 2 ft from the earth, with a balun at the feedpoint in 
the middle of the higher wire. 50 ohm coax runs from the balun to the 
shack, lying on the ground to further minimize noise pickup. It is 
strung along a fence on the lot line.

On all bands from 40m to 15m, the difference in signal to local noise 
ratio between it and the vertical transmit antenna and this antenna is 
considerable, up to 15dB. I suspect it would be a terrible transmit 
antenna, but it works fine as a receive antenna. DX signals are often 
heard by it much better than on the vertical. I don't have problems with 
the transmit signal overloading the receiver input, perhaps because they 
are polarized differently. The folded dipole feedpoint is about 50 ft. 
from the vertical antenna.

The advantage of the separate receive antenna is that I can use an NCC-1
phasing system box in conjunction with the handy RX ANT In/Out insert 
point on my K3. It's configured to use the Tx antenna signal from RX 
ANT Out as the noise signal into one of the NCC-1 inputs, with the other 
receive antenna connected to the other, and the NCC-1 output connected to 
RX ANT In. The difference in vertically polarized local noise pickup 
between the antennas lets me get a deep null on any particular noise 
source in the surrounding houses. The effect is to allow me to operate 
when I'd otherwise have to give up and be content with watching the 
man-made noise waveforms dance around on the P3 screen. Using the NCC-1 
introduces a directional effect of course, but as long as the signal isn't 
arriving at exactly the same azimuth as the local noise it works well.

I think that a lot of folks afflicted with strong local noise are using 
small so-called magnetic loop antennas for the same reason.

At times I feel like the Grinch in "How the Grinch Stole Christmas", 
muttering "...the noise noise noise!".

73,
Bob NW8L

> title, you're going to have to make a case for them even if you have to 
> stretch a bit.
>
> I remember bolting a 115 VAC coil Dowkey relay on the back of my DX100 for 
> antenna change over in 1960 or so.  It was several years before I had a 
> transceiver. The idea that separate antennas were the norm until transceivers 
> came along is nonsense, IMHO of course.  Even the publisher of this book, 
> ARRL, had many QST articles, such as "A Novice T.R. Switch", by Lew McCoy in 
> the January 1961 issue that popularized T.R. switches.  Lew even stated, "It 
> is always to the amateur's advantage to use the same antenna for both 
> transmitting and receiving."
>
> In the scheme of things, if my memory of the last 60 years isn't too faulty, 
> separate RX antennas are a relatively new thing, popularized for the lower 
> hand bands (40, 80 and 160), where of course they are supposed to have 
> advantages. Personally, I'm two (SV/A and FR/G) away from top of the Honor 
> Roll and have 9-band DXCC and I have never used a separate RX antenna.  I 
> guess I'll have to try one someday.
>
> Wes  N7WS
>
>
>
>
>
>
> On 9/9/2018 5:58 AM, hawley, charles j jr wrote:
>> The ARRL recently published a book “Receiving Antennas for the Radio 
>> Amateur”. It maintains that “The function of transmitting antennas is to 
>> radiate power efficiently, while the function of receiving antennas is to 
>> present the best signal-to-noise ratio to the receiver”. It maintains that 
>> “using the same antenna for transmitting and receiving roughly coincided 
>> with the advent of the transceiver in the 1950s and 1960s.” And “The 
>> glaring differences in priorities between transmitting and receiving 
>> antennas becomes...well...glaring...when we start looking into the concept 
>> of efficiency.” And “some of the most effective receiving antennas are 
>> abysmally poor performers when efficiency alone is considered”.
>> It’s an interesting book.
>> 
>> Chuck
>> KE9UW
>> 
>
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