Best VHF UHF receive antenna?

Discussion in 'VHF/UHF - 50Mhz and Beyond' started by KE7RUX, Oct 1, 2019.

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  1. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    FEI:

    Having, or not having, a CTCSS tone where standard squelch is involved, has absolutely no effect. You will activate a standard squelch (no squelch required) repeater no matter what. A CTCSS tone is required to activate a repeater that requires a tone and the tone has to be very close tolerance. However, when no tone is required it does not matter what the tone frequency is, or whether or not it is present, the receiver will activate the repeater so long as the signal is strong enough to release the squelch.

    As for hitting repeaters fairly far away:

    For over 20-years my wife's eldest sister lived in Panama City Beach, Florida. Every June, we would travel from Richardson, on the north side of Dallas, to that city leaving before dawn to arrive late in the afternoon. Almost every time, starting from before dawn until at least 10:00 AM and sometimes even after noon, going along I-20 to Shreveport and then going south to Baton Rouge, Louisiana, from my mobile, I could hit repeaters as far as St. Louis, even Springfield, Illinois, to the north, and even as far as Pensacola, Florida, to the southeast, without any problems. Being that I was usually on the 146.340 MHz / 146.940 MHz frequency pair, often several repeaters would come up at the same time.

    Coming back, again leaving before dawn, often repeaters as far north as Louisville, Kentucky, even as far north as Indianapolis, Indiana, and as far west at least Houston, and even farther west, could be accessed.

    Glen, K9STH
     
  2. KF5FEI

    KF5FEI Ham Member QRZ Page

    Ummmm..... We turned off our tone so we would not key our (Fort Worth) repeater, and potentially only key theirs.
     
  3. AI3V

    AI3V Ham Member QRZ Page

    Your just wrong Glen,

    The 3 biggest reasons that "back in the day" vhf propagation was like you remember,

    Were, relatively low tx power.

    Lousy rx sensitivity.

    And poor ftequency stability that demanded wide receiver bandwidths, and the associated noise.

    Take 10 ghz.

    My 5 milliwatt gunplexer running fm with a 200 khz bandwidth is a line of sight, 4/3 (on a good day !) Rig

    A modern 10 watt cw / gps locked / 1db nf receiver will work hundreds of miles.

    http://www.arrl.org/files/file/Cont... GHz Contest - Full Results - Version 1_2.pdf

    Vhf, its not your grandpa's line of sight band, anymore.

    Rege
     
  4. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    That is another matter!

    You didn't mention that you turned off the tone to keep from keying one of the local repeaters! It sounded like you thought you had to kill the tone to be able to access the Alabama repeater.

    You were already keying the Alabama repeater, you just could not receive it because of the local repeater.

    Until recently, when the RWK repeater finally went to CTCSS access, I could easily access the Waco repeater with the correct tone. However, since the RWK repeater is located less than a mile from my house (I can see the antenna, even through the trees from the roof of my house) there was no way to use it unless, for some reason, the RWK repeater was down.

    Until they went to separate CTCSS tones, there are 2-repeaters that I can easily access that have an input frequency of 147.000 MHz. Unfortunately, that frequency is the dividing line between low input and high input. As such, one repeater has the input frequency at 147.000 MHz and the output frequency at 146.400 MHz and the other has the output frequency at 147.600 MHz.

    Living 1/2-block from the highest point in Richardson, and have stacked, vertically polarized 11-element Yagi antennas, at 67-feet above ground, I do have a "fair" radius of communication.

    Of course not all line of sight propagation. But, the height, above mean sea level, is definitely above average!

    Glen, K9STH
     
  5. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    3V:

    You just don't get it! You have your mind made up and that is all.

    Frankly, no matter how I point out the fallacies of your arguments, you won't concede that there is such a thing as line of sight propagation. I keep saying that I agree that there are definitely other factors that can be involved and that line of sight is just one of those factors.

    Therefore, I just have to give up trying to convince you otherwise. Be happy in your beliefs!

    Glen, K9STH
     
  6. AI3V

    AI3V Ham Member QRZ Page

    https://duckduckgo.com/?q=superrefr...ignals+vs+temperature+inversion&t=fpas&ia=web

    This is the radio equivalent to a optical "mirage"

    True troposcatter does not rely on temperature inversion, but instead on the random motion of the atmosphere.

    Superrefraction -or "ducting"- is quite dependent on temperature inversion in the atmosphere, and can be predicted by measuring the temperature vs height.

    This "ducting" is much more efficient at bending radio waves thsn troposcatter, so it is usable by much more modest stations.

    Superrefraction is nowhere near a 24/7 mode like troposcatter.

    Other "exotic" modes include:

    Reflecting off the ionized trails of meteors.

    Reflecting off the aurora borealis or Australis.

    Reflecting off aircraft.

    Reflecting off rainclouds.

    Reflecting off tall buildings.

    And of course, the most exotic of them all,
    Reflecting off our moon.

    Rege
     
  7. KF5FEI

    KF5FEI Ham Member QRZ Page

    I thought that was rather obvious, when I stated we were hearing them on our local repeater frequency. Had they been running a different tone, like the Lufkin or Greenville repeater, we'd have switched to that tone.

    I have since generated a list of all the 34/94 repeaters and tones for quick reference, just in case I hear another repeater. Paid off when I talked to Wichita Falls on their repeater from the hill by the water tower near the house.
     
  8. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    There used to be another 34 / 94 repeater in Denton. The antenna was located on the water tower on the North Texas State University (now UNT) campus. As such, there was a lot of interference because neither repeater used any tone encoding. It took a lot of negotiations to get the Denton repeater to change frequency including paying for the crystals, etc., to accomplish this.

    As for not understanding your reasons for turning off the tone:

    It really was not obvious what you meant. This has happened to me. What I really thought was "obvious", because I understood why, sometimes is not "obvious" to others. Such happens to everyone.

    When the Fort Worth 34 / 94 repeater had the receive antenna at the 1000-foot level (transmit antenna was at the 600-foot level) of a tower on the east side, there was also a 146.940 MHz receiver connected to the receive antenna. That receiver was rebroadcast on a 440 MHz transmitter. Because of the vertical separation, the repeater transmitter could be transmitting and yet other repeaters, at times several hundred miles away, could be easily copied. Locals, especially in Dallas, etc., would listen to the 440 MHz link and work through other repeaters even if the Fort Worth repeater was activated.

    As for working stations outside of the normal repeater's area:

    Years ago, when I had additional station licenses in addition to my main call, one of the Fort Worth 34 / 94 repeater trustees wanted to call me. But, for some reason, he went "blank" on my 5-call but remembered my 4-call and called WA4MLI instead of WA5STI. Before I could grab the microphone, another friend, who lived in Sherman, decided to stir the pot and called my primary call, K9STH.

    Immediately, a newcomer to FM started calling "QRZ the 4, QRZ the 9". He didn't give any time between his repeated calls for anyone to tell him what was really happening. This calling went on for over an hour! Meanwhile, everyone decided just to let him have his "fun" even though everyone was really laughing behind his back.

    Glen, K9STH
     
  9. AI3V

    AI3V Ham Member QRZ Page

    I never said there was no such thing as line of sight.

    What I said was almost NO vhf propagation is true line of sight.

    If you do have a honest los path, you will find you can talk 1000 miles on a ht.

    Have you listened for AO50?

    It runs 250 MILLIWATTS, A QUARTER OF A WATT, TO A 1/4 WAVELENGTH WIRE.

    And you can receive it. WITH A HT AND A 1/4 WAVELENGTH WIRE.

    Now why again did you need to sell sheriff Billy bob a hundred watt radio? To talk across town?


    Rege
     
  10. K9STH

    K9STH Platinum Subscriber Volunteer Moderator Platinum Subscriber QRZ Page

    3V:

    You are backtracking!

    Sheriff "Billy Bob" no longer needs relatively high powered radios in many cases because they have gone to repeaters, trunking, etc.

    I used to be able to work a friend of mine, on 2-meters, with a Motorola H03NBC-1100A handheld transmitter, over 300-miles away, that ran 500 mW. Of course, he was in an airplane.

    How many actual base station antenna plots have you actually done? If any, how many of those have been verified by actual field measurements? The 4/3rds Earth intercept method is, by far, the most accurate of these plots and that method relies on line of sight predictions. On high band, they are at least over 90% accurate, at 450 MHz they are at least 95% accurate, and at 800 MHz / 896 MHz they approach 98% accuracy. There are things like reflections that can "fill in" some areas and, therefore, they are not 100% accurate.

    Frankly, over the years, I have done literally hundreds of these plots and a fair number of those had to be verified by actual field measurements. After a while, for those clients that I had done a number of the plots, after verifying the accuracy, did reduce, even stop, expending the money to do the field measurements.

    An example of line of sight propagation, on a 460 MHz repeater installation, was in an area south of Oklahoma City, Oklahoma. A distributor had sold an individual a repeater and he was wanting to have a community repeater for a certain city. This individual bought an existing tower several miles outside of the city (less than 10 miles away) and the land appeared very flat between the tower and the city. This individual had sold well over 100 mobile units before the repeater was in operation.

    Unfortunately, when the repeater was activated, coverage within the city was less than 10%. Until less than a mile from the city limits, no problem hitting the repeater. Then, several miles on the other side of the city, the repeater again became usable. In between, very little coverage. Eventually, as a consultant, I was called upon to try to solve the problem.

    Although the land "appeared flat", it actually dropped several hundred feet in elevation. Doing an Earth intercept plot it was very evident that the line of sight signal "hit the ground" very near where the repeater became unusable and the line of sight signal became "visible" on the other side of town. The city was in a "hole"!

    The individual had not paid any attention to the fact that the local cable television provider had an 800-foot tower just to receive the Oklahoma City television stations that were located less than 60-miles away! Of course, the endeavor was a failure and the individual refused to pay anyone involved, including me, even though he had been his own worst enemy. When the distributor, and I, started to sue him, we found that no lawyer in that part of Oklahoma would take the case. It seemed that the individual owned the only bail bond company in the area and, if any attorney even mentioned suing him, he would not allow any bonds for any of their clients. It also seemed that he "pulled" this same trick on a lot of businesses, etc.

    Now, how do you explain this particular situation if no line of sight propagation? Both the r.f. from the repeater and the r.f. from all of the television stations was blocked. Did the signal decide that it just didn't like the city so it stayed away? Methinks not!

    Maybe you want to use some other term than "line of sight"? However, that is the common term applied and most people in the r.f. communications world recognize what it means.

    Glen, K9STH
     

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