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#1
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In article ,
Dave Bushong wrote: That is actually not quite true. On an HT, the transmission line ends somewhere inside the radio. The SMA/BNC connector is part of the antenna proper. If you add a sleeve (as the previous poster, "dixon", says), you will be changing the antenna itself. ASCII schematic follows: befo I have been in the communications field for 35 years, and I have NEVER seen a SMA/BNC antenna connector on a Handheld Radio that didn't have a the RF Ground connected to the ground side of the connector. there are some that use different antenna connectors than SMA/TNC?BNC that are singleended but I have never seen one used that way. CFR (Call for Rference) Tell us all which radios your talking about. Make, Model, Version. Me |
#2
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Me wrote:
In article , Dave Bushong wrote: That is actually not quite true. On an HT, the transmission line ends somewhere inside the radio. The SMA/BNC connector is part of the antenna proper. If you add a sleeve (as the previous poster, "dixon", says), you will be changing the antenna itself. ASCII schematic follows: befo I have been in the communications field for 35 years, and I have NEVER seen a SMA/BNC antenna connector on a Handheld Radio that didn't have a the RF Ground connected to the ground side of the connector. there are some that use different antenna connectors than SMA/TNC?BNC that are singleended but I have never seen one used that way. CFR (Call for Rference) Tell us all which radios your talking about. Make, Model, Version. Me You missed my point, I think. The counterpoise is the (poor) metal of the radio and of the user's hand. Any connector/adapter will be coaxial and probably low loss, but the counterpoise stays put. The feedpoint rises but the "ground" plane does not. For an SMA adapter, it might not be enough to hear a difference, but the radiated signal will be worse when using such an adapter. 73, Dave |
#3
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In article ,
Dave Bushong wrote: You missed my point, I think. The counterpoise is the (poor) metal of the radio and of the user's hand. Any connector/adapter will be coaxial and probably low loss, but the counterpoise stays put. The feedpoint rises but the "ground" plane does not. For an SMA adapter, it might not be enough to hear a difference, but the radiated signal will be worse when using such an adapter. I'd say "may be worse" rather than "will be worse". In some cases, it may be better. From what I've seen (and measured) the actual impedances, "counterpoise" effectiveness, etc. of HT antenna setups vary all over the map, and change constantly depending on a whole bunch of factors... how you grip the HT, whether you happen to be wearing a glove, how you angle the HT near your head (antenna-loading effects from the head can make SWR change dramatically), and probably whether you're sweating or not. A typical HT case is almost certainly _not_ serving as a tuned counterpoise at 2 meters, nor is your arm and body. Adding a centimeter or three of SMA-to-BNC connector to the length of the "counterpoise" may have some small effect in some cases, but I believe that [1] it's as likely to work for you as against you, and [2] it's probably less than the sorts of impedance variations which a typical HT has to face every day as it's moved around the user's head during transmission. -- Dave Platt AE6EO Hosting the Jade Warrior home page: http://www.radagast.org/jade-warrior I do _not_ wish to receive unsolicited commercial email, and I will boycott any company which has the gall to send me such ads! |
#4
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Not to mention the fact that the reason you're adding the adapter is most
likely because you are putting a better antenna on the HT. I doubt what you *might* lose by moving the feedpoint away from the "counterpoise" is not as much as you gain by changing the antenna; otherwise, why bother? At higher frequencies this may not be the case, but probably not within the realm of a dual-band HT. I've been using the Gulyas adapter for years now. I use it primarily for attaching a Smiley 270 telescopic whip to my VX-5, since that antenna works very well configured as a 5/8-wave on 70cm. The relative gain in performance over the stock antenna is quite noticeable, so in that case, the adapter causes no problems. The fit and appearance of the adapter on that rig is great, too! - Doug "Dave Platt" wrote in message ... In article , Dave Bushong wrote: You missed my point, I think. The counterpoise is the (poor) metal of the radio and of the user's hand. Any connector/adapter will be coaxial and probably low loss, but the counterpoise stays put. The feedpoint rises but the "ground" plane does not. For an SMA adapter, it might not be enough to hear a difference, but the radiated signal will be worse when using such an adapter. I'd say "may be worse" rather than "will be worse". In some cases, it may be better. From what I've seen (and measured) the actual impedances, "counterpoise" effectiveness, etc. of HT antenna setups vary all over the map, and change constantly depending on a whole bunch of factors... how you grip the HT, whether you happen to be wearing a glove, how you angle the HT near your head (antenna-loading effects from the head can make SWR change dramatically), and probably whether you're sweating or not. A typical HT case is almost certainly _not_ serving as a tuned counterpoise at 2 meters, nor is your arm and body. Adding a centimeter or three of SMA-to-BNC connector to the length of the "counterpoise" may have some small effect in some cases, but I believe that [1] it's as likely to work for you as against you, and [2] it's probably less than the sorts of impedance variations which a typical HT has to face every day as it's moved around the user's head during transmission. -- Dave Platt AE6EO |
#5
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Dave Platt wrote:
In article , Dave Bushong wrote: You missed my point, I think. The counterpoise is the (poor) metal of the radio and of the user's hand. Any connector/adapter will be coaxial and probably low loss, but the counterpoise stays put. The feedpoint rises but the "ground" plane does not. For an SMA adapter, it might not be enough to hear a difference, but the radiated signal will be worse when using such an adapter. I'd say "may be worse" rather than "will be worse". In some cases, it may be better. [...] Tell me, specifically, in which cases that my info would not be true. I made some measurements before I posted. Did you? I was just saying that extending the feedpoint / current node, as was suggested, will lower the radiated power. I measured field strength measurements and then posted my results. I still feel that the more aluminum in the sky, the better. Even if there is some loss in adapters... mmmm.... bigger antennas, happier hams. 73, Dave kz1o |
#6
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HT's are as close to having an isotropic antenna as anything to be had.
Dave WD9BDZ Dave Platt wrote: In article , Dave Bushong wrote: You missed my point, I think. The counterpoise is the (poor) metal of the radio and of the user's hand. Any connector/adapter will be coaxial and probably low loss, but the counterpoise stays put. The feedpoint rises but the "ground" plane does not. For an SMA adapter, it might not be enough to hear a difference, but the radiated signal will be worse when using such an adapter. I'd say "may be worse" rather than "will be worse". In some cases, it may be better. From what I've seen (and measured) the actual impedances, "counterpoise" effectiveness, etc. of HT antenna setups vary all over the map, and change constantly depending on a whole bunch of factors... how you grip the HT, whether you happen to be wearing a glove, how you angle the HT near your head (antenna-loading effects from the head can make SWR change dramatically), and probably whether you're sweating or not. A typical HT case is almost certainly _not_ serving as a tuned counterpoise at 2 meters, nor is your arm and body. Adding a centimeter or three of SMA-to-BNC connector to the length of the "counterpoise" may have some small effect in some cases, but I believe that [1] it's as likely to work for you as against you, and [2] it's probably less than the sorts of impedance variations which a typical HT has to face every day as it's moved around the user's head during transmission. |
#7
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In article ,
Dave Bushong wrote: Me wrote: In article , Dave Bushong wrote: That is actually not quite true. On an HT, the transmission line ends somewhere inside the radio. The SMA/BNC connector is part of the antenna proper. If you add a sleeve (as the previous poster, "dixon", says), you will be changing the antenna itself. ASCII schematic follows: befo I have been in the communications field for 35 years, and I have NEVER seen a SMA/BNC antenna connector on a Handheld Radio that didn't have a the RF Ground connected to the ground side of the connector. there are some that use different antenna connectors than SMA/TNC?BNC that are singleended but I have never seen one used that way. CFR (Call for Rference) Tell us all which radios your talking about. Make, Model, Version. Me You missed my point, I think. The counterpoise is the (poor) metal of the radio and of the user's hand. Any connector/adapter will be coaxial and probably low loss, but the counterpoise stays put. The feedpoint rises but the "ground" plane does not. For an SMA adapter, it might not be enough to hear a difference, but the radiated signal will be worse when using such an adapter. 73, Dave No, you didn't read roy's post on how feedline and antennas systems work...... Me |
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