Topband: Location of WF RX Antenna. Need Expert Advice

[Kees Nijdam]

It depends not only on distance. Also the gain of both (TX- and RX) antennas matters.
The lower the gain of the RX antenna, the more the re-radiating TX antenna (or other nearby wires/towers) will modify its pattern. Low gain loops, such as the Waller flag, are more critical compared to beverages.
One of my beverages runs 5 meters from my TX antenna, and is useless without detuning the TX antenna. The other beverage has its feedpoint at 40 meter distance and runs away from the TX antenna and the influence is minimal.
My advice: allways check the interaction by detuning the TX antenna(s). Use an AM broadcasting station as reference. 

Kees, PE5T 


Verzonden vanuit Mail voor Windows 10

Van: W0MU Mike Fatchett
Verzonden: dinsdag 31 juli 2018 00:29
Aan: topband at contesting.com
Onderwerp: Re: Topband: Location of WF RX Antenna. Need Expert Advice

Interesting.  My rcv array is probably 500 ft from the Xmit antenna or 
any antenna so I am probably ok?  My 70ft tower is 70ish feet from the 
160 inverted l.  I wonder if there is much to be gained by attempting to 
detune the tower.

W0MU


On 7/30/2018 10:44 AM, Pete Rimmel N8PR wrote:
> Joe,
>
> You might consider that there is interaction of the Waller Flag and 
> the other two towers as well as your transmit antenna while on receive.
>
> I suggest that you detune both of the other towers, as well as the 
> transmit antenna while using the WF on receive to eliminate them 
> re-radiating noise to the WF.
>
> Take a look at my YouTube video entitled:  "N8PR TX Antenna 
> Construction and Detuning effects on receive Noise"
>
> https://www.youtube.com/watch?v=sk6PVl7uaBM&t=257s
>
> I think that you will see that the detuning is worthwhile.
>
> 73,  PeteR  N8PR
> ----------------------------------------------------------------------
>
> 1. Location of WF RX Antenna.  Need Expert Advice
>
> {{I am hoping to construct a Waller Flag RX antenna on a 56' Heights
> aluminum tower for 80 and 160M RX.  The ideal location from aesthetic,
> RF and maintenance-of-a-civil -family-climate standpoints is midway
> (150' separation) between two existing LM-470 towers now separated by
> about 300'.  One has a 4-element Steppir and a 13-element 2M yagi on it
> and the other a 2 element 30/40M quad.  Obviously, the WF would not be
> used simultaneously as the two existing antennas, and the Heights tower
> would be well grounded..  Am I asking for a round of battles of trying
> to mitigate interaction problems on either TX or RX on any of the bands
> involved?  Would an easy answer to my question be obtained from an EZNEC
> simulation, especially since I already have models of the two current
> antennas?
>
> I suspect other people on this reflector have been here before. I'd
> appreciate any practical advice.
>
>
> Many thanks and 73,
>
> Joe
> K2XX}}
>
>
>
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