Re: Topband: NCC-2 antenna pattern?
OK Kenny. I understand now. Not all of the TX will be under control of the transceiver at the operating position that is using the in-band antenna, so you need RF protection while also receiving in-band. I think your phased vertical idea could work. But, a pair of flag antennas would also work well. And they're ground independent too. You would want endfire arrays here. As was mentioned, about 100-foot separation is a good starting point, and that's inline of course. In the case of either the 2 vertical array or the 2 flag array you could use coax sections cut to the appropriate length considering the velocity factor of the coax to get the pattern that you want. One other thing about the flag option is that the antennas can be either unterminated, and the pair will give you a really deep null at low elevations, or you can add VACTROL termination and adjust it on the fly. In your case with the TX going on I think I'd install the VACTROLs, tweak the terminating resistance to the best values, and then measure it and replace the VACTROLs with a several watt non-inductive combination of fixed resistors that give you that same value. No TX worries then. Terminated, the flags will give you a deeper back null than the verticals will. The flags don't need to be huge. You didn't specify the bands of interest but a 10-foot by 25-foot flag with the bottom wire 3-feet off of the ground works well from mediumwave to over 40 meters, maybe higher. I have a pair of these in an inline configuration and unterminted I can sweep a null from horizon to horizon. Terminated I can deepen the null and swing the max null angle some against the horizon. I have my flags setup so they're moveable. I used 4 5-gallon plastic buckets and put a 3 foot PVC pipe with a cap centered, bolted the cap to the center of the bucket bottom, and then filled the buckets with concrete. I can move them and they stay put even in high winds. I have a 10-foot piece of PVC in a PVC coupling on top of the bucket cemented pipe section and on each end that supports the antenna loop. The flags are fed in the lower corner via twisted-pair transmission line and that is back to the shack where any transformation or preamping is done. And then on to the SDR. The termination is at the opposite corner. I modeled and tested corner feed vs center side feed and termination and I did not notice any difference in performance. You could do something similar with a KAZ or Superloop and that would be longer but need only one support at the center. Just a few more thoughts for you to consider... Rick Kunath, K9AO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: NCC-2 antenna pattern?
HI Tree, Thanks for your input. I'm leaning towards a 2 element phased vertical array with a quasi-cardioid pattern for my application. it will avoid any phasing box overload issues. 73, Kenny K2KW On Sun, Dec 17, 2023 at 2:12 PM Tree wrote: > I think the concern about overload is another reason to not consider it. > That box is not designed to handle a strong signal like another transmitter. > > One other solution is to try and come up with a coax length that presents > an out of phase signal at the right amplitude to cancel it out on the 2nd > receiver. I know W8JI has done this on 160. > > I have been successful with in-band receiving on 160 with a loop antenna > about 800 feet away from the TX vertical with the null parked on the TX > antenna. On 20 meters, I have done it with about 500 feet separation. > It's obviously a lot easier with low power (like used in the NAQP). The > K5KA muiti-ops used an all band vertical for RX for the in band radios. > > Tree N6TR > > Tree N6TR > > On Sun, Dec 17, 2023 at 10:41 AM Kenny Silverman > wrote: > >> Thanks for all the comments, but knowing what the resulting antenna >> pattern seems elusive. >> >> I need in-band RX antenna for a mult station. Typically antenna >> separation, front-to-back and polarization are the main tools for that. >> When I run out of room >> >> I was wondering if phasing from an NCC-2 box is another tool to consider. >> But I don’t want to consider it without knowing what the resulting pattern >> would be. >> >> Many thanks, Kenny K2KW >> >> >> Regards , Kenny >> >> > On Dec 17, 2023, at 1:05 PM, Rick Kunath wrote: >> > >> > I'm not sure we still understand the intended application of the >> original poster, I know I don't. >> > >> > I've done lots of work with loops and loop arrays phased either >> passively (active or entirely passive external phaser boxes) or actively >> phased via an SDR but none of that would eliminate the need for RX >> protection on the receive antenna and any electronics associated with it. >> So if the OP is trying to get away from any protection from the TX energy, >> I think this is false hope. A loop mounted preamp makes that more >> complicated. And The NCC2 does have options for protection boards for TX >> internally. There are several types available and also internal preamps. >> But it cannot set a specific amplitude and phase angle on the phasing. I >> don't have one and haven't ever had the pleasure of using one, but those >> that do tell me they enjoy them and they work well especially for live >> listening. I do like the idea of having the electronics at the shack end of >> things and as little as possible at the antenna when possible, though >> depending on the specifics you will have VACTROL devices or other >> termination devices at at the antenna with at least some antenna types. >> > >> > Preset patterns and unattended work are another case entirely and this >> is best done with specific phase coherent dual-channel SDRs and a specific >> SDR application. >> > >> > I think doing what the OP might want as I might understand it is >> possible, but I'd like to hear more from him about his hopes for the >> project. >> > >> > Rick Kunath, K9AO >> > >> >> _ >> Searchable Archives: http://www.contesting.com/_topband - Topband >> Reflector >> > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: NCC-2 antenna pattern?
I think the concern about overload is another reason to not consider it. That box is not designed to handle a strong signal like another transmitter. One other solution is to try and come up with a coax length that presents an out of phase signal at the right amplitude to cancel it out on the 2nd receiver. I know W8JI has done this on 160. I have been successful with in-band receiving on 160 with a loop antenna about 800 feet away from the TX vertical with the null parked on the TX antenna. On 20 meters, I have done it with about 500 feet separation. It's obviously a lot easier with low power (like used in the NAQP). The K5KA muiti-ops used an all band vertical for RX for the in band radios. Tree N6TR Tree N6TR On Sun, Dec 17, 2023 at 10:41 AM Kenny Silverman wrote: > Thanks for all the comments, but knowing what the resulting antenna > pattern seems elusive. > > I need in-band RX antenna for a mult station. Typically antenna > separation, front-to-back and polarization are the main tools for that. > When I run out of room > > I was wondering if phasing from an NCC-2 box is another tool to consider. > But I don’t want to consider it without knowing what the resulting pattern > would be. > > Many thanks, Kenny K2KW > > > Regards , Kenny > > > On Dec 17, 2023, at 1:05 PM, Rick Kunath wrote: > > > > I'm not sure we still understand the intended application of the > original poster, I know I don't. > > > > I've done lots of work with loops and loop arrays phased either > passively (active or entirely passive external phaser boxes) or actively > phased via an SDR but none of that would eliminate the need for RX > protection on the receive antenna and any electronics associated with it. > So if the OP is trying to get away from any protection from the TX energy, > I think this is false hope. A loop mounted preamp makes that more > complicated. And The NCC2 does have options for protection boards for TX > internally. There are several types available and also internal preamps. > But it cannot set a specific amplitude and phase angle on the phasing. I > don't have one and haven't ever had the pleasure of using one, but those > that do tell me they enjoy them and they work well especially for live > listening. I do like the idea of having the electronics at the shack end of > things and as little as possible at the antenna when possible, though > depending on the specifics you will have VACTROL devices or other > termination devices at at the antenna with at least some antenna types. > > > > Preset patterns and unattended work are another case entirely and this > is best done with specific phase coherent dual-channel SDRs and a specific > SDR application. > > > > I think doing what the OP might want as I might understand it is > possible, but I'd like to hear more from him about his hopes for the > project. > > > > Rick Kunath, K9AO > > > > _ > Searchable Archives: http://www.contesting.com/_topband - Topband > Reflector > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: NCC-2 antenna pattern?
Thanks for all the comments, but knowing what the resulting antenna pattern seems elusive. I need in-band RX antenna for a mult station. Typically antenna separation, front-to-back and polarization are the main tools for that. When I run out of room I was wondering if phasing from an NCC-2 box is another tool to consider. But I don’t want to consider it without knowing what the resulting pattern would be. Many thanks, Kenny K2KW Regards , Kenny > On Dec 17, 2023, at 1:05 PM, Rick Kunath wrote: > > I'm not sure we still understand the intended application of the original > poster, I know I don't. > > I've done lots of work with loops and loop arrays phased either passively > (active or entirely passive external phaser boxes) or actively phased via an > SDR but none of that would eliminate the need for RX protection on the > receive antenna and any electronics associated with it. So if the OP is > trying to get away from any protection from the TX energy, I think this is > false hope. A loop mounted preamp makes that more complicated. And The NCC2 > does have options for protection boards for TX internally. There are several > types available and also internal preamps. But it cannot set a specific > amplitude and phase angle on the phasing. I don't have one and haven't ever > had the pleasure of using one, but those that do tell me they enjoy them and > they work well especially for live listening. I do like the idea of having > the electronics at the shack end of things and as little as possible at the > antenna when possible, though depending on the specifics you will have > VACTROL devices or other termination devices at at the antenna with at least > some antenna types. > > Preset patterns and unattended work are another case entirely and this is > best done with specific phase coherent dual-channel SDRs and a specific SDR > application. > > I think doing what the OP might want as I might understand it is possible, > but I'd like to hear more from him about his hopes for the project. > > Rick Kunath, K9AO > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: NCC-2 antenna pattern?
I'm not sure we still understand the intended application of the original poster, I know I don't. I've done lots of work with loops and loop arrays phased either passively (active or entirely passive external phaser boxes) or actively phased via an SDR but none of that would eliminate the need for RX protection on the receive antenna and any electronics associated with it. So if the OP is trying to get away from any protection from the TX energy, I think this is false hope. A loop mounted preamp makes that more complicated. And The NCC2 does have options for protection boards for TX internally. There are several types available and also internal preamps. But it cannot set a specific amplitude and phase angle on the phasing. I don't have one and haven't ever had the pleasure of using one, but those that do tell me they enjoy them and they work well especially for live listening. I do like the idea of having the electronics at the shack end of things and as little as possible at the antenna when possible, though depending on the specifics you will have VACTROL devices or other termination devices at at the antenna with at least some antenna types. Preset patterns and unattended work are another case entirely and this is best done with specific phase coherent dual-channel SDRs and a specific SDR application. I think doing what the OP might want as I might understand it is possible, but I'd like to hear more from him about his hopes for the project. Rick Kunath, K9AO _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: NCC-2 antenna pattern?
If you can get that close I suggest a small explosive charge 73, Pete N4ZR On 12/17/2023 10:31 AM, John Kaufmann via Topband wrote: If you are going to use the NCC-2 to null a nearby in-band transmitter, I think it's very likely that the NCC-2 will get overloaded by the extremely strong RF and not be usable. I've tried this before and found that to be the case. In fact, I designed my own totally passive nuller to get around this problem. It worked and was able to create very deep nulls on an in-band transmitter, but turned out to be very impractical because it required constant adjustment to maintain a null as antennas were changed or rotated. The other thing to consider is that if the interference is coming from the same direction as a signal you want to hear, nulling the interference will also null the signal. Nulling works best when the interference comes from a very different direction than the signal. It also helps greatly if the interference sensing antenna receives the interference much more strongly than the main antenna. This can be done by placing the sensing antenna close to the interference source, if that's possible. 73, John W1FV -Original Message- From: Topband On Behalf Of Kenny Silverman Sent: Saturday, December 16, 2023 10:05 PM To: Rick Kunath Cc: topband Subject: Re: Topband: NCC-2 antenna pattern? Rick, my application is for an in-band RX antenna, but on a higher band. I just thought the guys here might know more about the NCC-2, MFJ or QRM eliminator than most others. One thought was to create a 2 ele phased vertical array for the RX antenna with a known pattern and put the null towards the TX array, along with physical separation to allow in-band receiving. But I was thinking an adjustable phasing system may produce a better null. But I wouldn’t want the adjustable unit to create a clover leaf pattern for example. One null might take out the interference but another null towards the desired receiving direction might be created and is not desired. I hope I’m explaining this well. Regards , Kenny K2KW On Dec 16, 2023, at 9:47 PM, Rick Kunath wrote: What's your application Kenny and what would you be feeding the antenna output of the phaser into? Rick Kunath, K9AO _ Searchable Archives:http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives:http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
Re: Topband: NCC-2 antenna pattern?
If you are going to use the NCC-2 to null a nearby in-band transmitter, I think it's very likely that the NCC-2 will get overloaded by the extremely strong RF and not be usable. I've tried this before and found that to be the case. In fact, I designed my own totally passive nuller to get around this problem. It worked and was able to create very deep nulls on an in-band transmitter, but turned out to be very impractical because it required constant adjustment to maintain a null as antennas were changed or rotated. The other thing to consider is that if the interference is coming from the same direction as a signal you want to hear, nulling the interference will also null the signal. Nulling works best when the interference comes from a very different direction than the signal. It also helps greatly if the interference sensing antenna receives the interference much more strongly than the main antenna. This can be done by placing the sensing antenna close to the interference source, if that's possible. 73, John W1FV -Original Message- From: Topband On Behalf Of Kenny Silverman Sent: Saturday, December 16, 2023 10:05 PM To: Rick Kunath Cc: topband Subject: Re: Topband: NCC-2 antenna pattern? Rick, my application is for an in-band RX antenna, but on a higher band. I just thought the guys here might know more about the NCC-2, MFJ or QRM eliminator than most others. One thought was to create a 2 ele phased vertical array for the RX antenna with a known pattern and put the null towards the TX array, along with physical separation to allow in-band receiving. But I was thinking an adjustable phasing system may produce a better null. But I wouldn’t want the adjustable unit to create a clover leaf pattern for example. One null might take out the interference but another null towards the desired receiving direction might be created and is not desired. I hope I’m explaining this well. Regards , Kenny K2KW > On Dec 16, 2023, at 9:47 PM, Rick Kunath wrote: > > What's your application Kenny and what would you be feeding the antenna > output of the phaser into? > > Rick Kunath, K9AO > _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector _ Searchable Archives: http://www.contesting.com/_topband - Topband Reflector
