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5/8 Wave groundplane 1.5:1 SWR all over the band
- Thread starter mattsowders1989
- Start date
DB, IMO you make a valid point, but here you and others are talking about and giving us very simple examples of multi-band antenna systems that operate over many different HF bands and frequencies. There are few comparisons and a world of differences in such operations compared to CB.
So, here we are in the CB Antenna Section talking about CB antenna setups and then a few Ham Radio folks drop by and talk to us about their ideas, while referencing their far more complicate multi-band type operations...and seemingly do it is the least informative way possible.
i don't get it.
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Steve, here is an example of a situation where M0GVZ posted his ideas for a Ham Inverted L antenna in the CB Antenna section as an example a while back. Henry and I both questioned his point, and I posted an Inverted L model I found somewhere on the Internet as my example.
This not to say that M0GVZ was wrong, but i was looking for more information, and unless I asked...it would likely not be forthcoming.
I don't consider myself anywhere near knowledgeable enough to try and pick M0GVZ's mind on that issue, but Gary (BJ Radionut) was kind enough to help explain in understandable terms...one likely expatiation for the vagueness I saw in M0GVZ's initial words.
Long wire antenna for cb?
This not to say that M0GVZ was wrong, but i was looking for more information, and unless I asked...it would likely not be forthcoming.
I don't consider myself anywhere near knowledgeable enough to try and pick M0GVZ's mind on that issue, but Gary (BJ Radionut) was kind enough to help explain in understandable terms...one likely expatiation for the vagueness I saw in M0GVZ's initial words.
Long wire antenna for cb?
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i just feel like a soldered connection is better than two points only touching. Not sure about this "JoGunn". im just a hobbyist. i dont claim to know it all or know better than others.
Shadetree Mechanic
Delaware Base Station 808
I agree. I would definitely prefer a soldered connection if it is out in the elements.
Eddie
You are correct in you observations.
Yes, this section is for 27 MHz .
I see what you are talking about.
Maybe we are making it confusing for operators that are concerned with one band and were 99% of the guys are using Coax as the only feed line.
Some of the points that we, as hams, put here are mute.
This is how I am going to state this bearing in mind what I have just said.
If you look at most of the paperwork that comes with new CB radios, the general instructions say that if your SWR is above 2 you should adjust your antenna.
This is a stock CB operating within the design limits of the manufacturer.
Most of the loss at 27 MHz occur's in the feed line.
In most typical mobile installations the feed line is short so it is not so critical.
In a base station this loss can be substancial.
In mobile setups that are running high power were stress is placed on the equipment( for what ever reason)
It is better to have reflect as low as possible to not add more stress to the situation.
So looking at the subject in this light I will say that, yes it is benifical to try to achieve a low swr reading to prevent feed line losses.
Yes it is good to have low SWR to prevent damage to equipment that is already working close to the limit.
Yes it is good to have low SWR to try to get as much power to the feed line point at the antenna.
I think this is the point you are wanting to make.
How say you ?
73
Jeff
You are correct in you observations.
Yes, this section is for 27 MHz .
I see what you are talking about.
Maybe we are making it confusing for operators that are concerned with one band and were 99% of the guys are using Coax as the only feed line.
Some of the points that we, as hams, put here are mute.
This is how I am going to state this bearing in mind what I have just said.
If you look at most of the paperwork that comes with new CB radios, the general instructions say that if your SWR is above 2 you should adjust your antenna.
This is a stock CB operating within the design limits of the manufacturer.
Most of the loss at 27 MHz occur's in the feed line.
In most typical mobile installations the feed line is short so it is not so critical.
In a base station this loss can be substancial.
In mobile setups that are running high power were stress is placed on the equipment( for what ever reason)
It is better to have reflect as low as possible to not add more stress to the situation.
So looking at the subject in this light I will say that, yes it is benifical to try to achieve a low swr reading to prevent feed line losses.
Yes it is good to have low SWR to prevent damage to equipment that is already working close to the limit.
Yes it is good to have low SWR to try to get as much power to the feed line point at the antenna.
I think this is the point you are wanting to make.
How say you ?
73
Jeff
As long as the connection is properly supported, properly assembled and waterproofed correctly, mechanical connections are sufficient in most installations.
Even a direct soldered connection is subject to failure if not supported and properly protected from weather.
73
Jeff
Shadetree Mechanic
Delaware Base Station 808
True, a soldered connection should not be relied on as the only mechanical connection. Also the wire insulation still needs to be sealed to prevent water intrusion. When I have an electrical connection out doors that is not soldered, I will use a dab of silicone dielectric grease to seal out the elements. On my equipment trailer, I got tired of redoing the light wiring and started putting a squirt of dielectric grease inside the connector before I put the wires in to crimp or screw down. It has to cover all the bare wire to seal the insulation too.
Jeff, thanks for your thoughtful comments. You've always been considerate with me.
I don't want the Ham operators to STOP making their comments...just because this is the CB Section where operations are IMO way more simple.
I think some could have a little more consideration in their approach however. Sometimes more technical type of topics and old ideas...just don't share well. For sure this can happen when concepts are given with scant, categorical and dismissive type information, (my way or the highway). Sometimes difficult ideas need more patients and at best can be slow in the process towards constructive change.
IMO, it is good that CB operators get some exposure to new and more advanced ideas, and concepts...hopefully working on their thinking, rather than working on their emotions and possible ill-temper.
That's all.
Man Im confused I was always told to get your swr as low as possible...
Man Im confused I was always told to get your swr as low as possible...
I think when we were told that SWR was a meaningless bit of information and that we were all just slaves of SWR's, was what I was talking about when I said,
"I don't get it."
Thanks for your reply Eddie.
You have invested a lot of time and energy here helping many understand complex subjects dealing with RF antennas.
You have changed my mind in the past about things related to antennas, and helped others to really think about this subject, do to your hard work and it is apprecitated.
Things are not always clear in written post's on a internet forum.
I have meet many casual users of CB radios that are not even aware of the need to check SWR on a CB radio setup.
They just buy a radio and antenna and install them and never think anything about it.
Maybe it would be better to say that the difference between 1.3 to 1 SWR and a " perfectly flat " SWR is not super critical, depending on how much effort you have to go through to try to achieve that perfect reading and, each operators station set up?
No one should be ridiculed for working to achieve as low a SWR reading as possible.
I shall continue to try to think about your comments here before I am so quick to ' react like a Ham ' before hitting the post button in CB areas.
Thanks Eddie.
73
Jeff
You have invested a lot of time and energy here helping many understand complex subjects dealing with RF antennas.
You have changed my mind in the past about things related to antennas, and helped others to really think about this subject, do to your hard work and it is apprecitated.
Things are not always clear in written post's on a internet forum.
I have meet many casual users of CB radios that are not even aware of the need to check SWR on a CB radio setup.
They just buy a radio and antenna and install them and never think anything about it.
Maybe it would be better to say that the difference between 1.3 to 1 SWR and a " perfectly flat " SWR is not super critical, depending on how much effort you have to go through to try to achieve that perfect reading and, each operators station set up?
No one should be ridiculed for working to achieve as low a SWR reading as possible.
I shall continue to try to think about your comments here before I am so quick to ' react like a Ham ' before hitting the post button in CB areas.
Thanks Eddie.
73
Jeff
What I always wonder whenever these topics come up...is there any reason NOT to aim for a center-of-band low SWR on a CB antenna?
I’ve not dealt with many base antennas...but getting a mobile antenna to below 1.5 has never been a challenge in any application I’ve ever dealt with...so why not?
After all, that’s what most CBers have or have access to: a commercial antenna fed with 50ohm coax, and a SWR meter...and usually an instruction sheet that says put the lowest SWR in the middle and call it good.
I’ve not dealt with many base antennas...but getting a mobile antenna to below 1.5 has never been a challenge in any application I’ve ever dealt with...so why not?
After all, that’s what most CBers have or have access to: a commercial antenna fed with 50ohm coax, and a SWR meter...and usually an instruction sheet that says put the lowest SWR in the middle and call it good.
Shadetree Mechanic
Delaware Base Station 808
Well from what I have read, there is another parameter called resonance that is important to look at for antenna performance. The only way to measure it is with an antenna anylizer. This is the point where the capacitive reactance and inductive reactance both equal zero. This is usually not at 1 to 1 swr. So the resonance has to do with effeciency and the swr is reflected power. Both are important for different reasons. If I got any of that wrong, someone please correct me.