vhf/uhf antenna
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n5ims
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Are you talking about this antenna http://www.hol4g.com/ac/product.aspx?number=LAR-NMOQ-C&p=172968&sc=0? If so, what frequency did you cut the antenna to be resonant at (http://www.larsen-antennas.com/docfiles/ASB8/CutCharts/Q_Series.pdf)? That is not a wide-band antenna, but simply an antenna that can be cut down to cover a 3 - 4 MHz band of frequencies withing that 136 - 512 MHz range. You're fortunate that the ham 2 meter band and the ham 70 cm band are harmonically related so that a 1/4 wave 2 meter antenna will work on the 70 cm band as well SWR wise.
You may want to get one of the dual-band antennas (like the Larsen 2/70 series) that properly covers both bands with a single antenna and is already cut for the ham frequencies. They make various models in that series that trade height for gain. The NMO 2/70SH is the shortest at 19" and has unity gain on 2 and a bit of gain on 70 cm. The NMO 2/70B has an open coil and looks similar to the old cellular antennas at 33.5" while the NMO 2/70C has a closed coil at 37.2" and both have similar gain figures. Details on them are here Larsen Amateur Mobile Antennas NMO 440B
You may want to get one of the dual-band antennas (like the Larsen 2/70 series) that properly covers both bands with a single antenna and is already cut for the ham frequencies. They make various models in that series that trade height for gain. The NMO 2/70SH is the shortest at 19" and has unity gain on 2 and a bit of gain on 70 cm. The NMO 2/70B has an open coil and looks similar to the old cellular antennas at 33.5" while the NMO 2/70C has a closed coil at 37.2" and both have similar gain figures. Details on them are here Larsen Amateur Mobile Antennas NMO 440B
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i never did cut the antenna, what length should I cut it to? I have other actual dual band antennas, including the nice one that maxrad makes...but I love the length and color of this antenna, its practically invisible.
n5ims
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Please post a link to the exact model of antenna you have. If it was the one I had the link to in my reply (the Larsen NMOQ-C) than the cutting chart also had a link in that post. I could say to cut it to 19" (which is what many 2 meter 1/4 wave verticals need to be) but if you have a different model that could be way off due to the design of that specific antenna. It also matters if the antenna has a spring or not on the mount. Even the type of mount you have matters since they often are different sizes (as indicated in the linked cutting chart for that antenna one mount model is cut shorter than the other mount model).
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When you studied for your amateur radio license, antenna tuning should have been covered.
468 divided by frequency in mhz.
73,
n9zas
jparks29
John McClane
+1
How the %^&( did someone get their ticket without even understanding antenna tuning?
Are the tests that dumbed down these days?
joseph2020
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kc0usq, the length of the antenna is not hard to figure out. There's a direct relationship between resonant frequency and antenna length. The general equation is total length = (constant) divided by frequency: l = x/f
For 146 mhz (2 meter) dipole you use these easy equations. for a half wave antenna = 468 / 146 = 3.205 feet = 38.46 inches total length. for a quarter wave use 234 / 146 = 1.6 feet = 19.23 inches. 468 and 234 as the constants will always give you the total length in feet for any frequency for 1/2 and 1/4 wavelenghts.
For 146 mhz (2 meter) dipole you use these easy equations. for a half wave antenna = 468 / 146 = 3.205 feet = 38.46 inches total length. for a quarter wave use 234 / 146 = 1.6 feet = 19.23 inches. 468 and 234 as the constants will always give you the total length in feet for any frequency for 1/2 and 1/4 wavelenghts.
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+1
How the %^&( did someone get their ticket without even understanding antenna tuning?
Are the tests that dumbed down these days?
It's because the freaking answers are posted for all to memorize before they go take their test. It was that way when I went to take my first test back in the early 90's. There was a group of people all quizzing each other on the potential questions. I guess I was in the dark, because I had no idea that I could have just memorized the answers. I used a book called, "Now You're Talking" from Radio Shack and read and made sure I understood it before I took my test. It is amazing at the number of amateur radio operators that ask basic questions that they should know the answer to.
To answer the original question.
It's very doubtful is an antenna being 'wide banded' will damage a radio. If you use that antenna for a particular frequency that it hasn't been designed for, without re-tuning it, then sure, there's a possibility that there could be some problem. That 'wide banded' thingy is a -very- non-exact term, can mean a lot of different things depending on who'z using it and how it's used.
I think all antennas can be 'tweaked' to perform 'better', none are ever exactly 'right' straight out of the box. So, tuning it is definitely an option. There can be quite a difference between being "in the ball park" and "sliding across home plate". That's up to you...
- 'Doc
It's very doubtful is an antenna being 'wide banded' will damage a radio. If you use that antenna for a particular frequency that it hasn't been designed for, without re-tuning it, then sure, there's a possibility that there could be some problem. That 'wide banded' thingy is a -very- non-exact term, can mean a lot of different things depending on who'z using it and how it's used.
I think all antennas can be 'tweaked' to perform 'better', none are ever exactly 'right' straight out of the box. So, tuning it is definitely an option. There can be quite a difference between being "in the ball park" and "sliding across home plate". That's up to you...
- 'Doc
ST-Bob
Member
That antenna is a simple 1/4 wave and should be cut to the appropriate length for the frequency you're transmitting on using the cutting chart that came with it (or is available on-line). At unity gain (0 dBd) you're not going to get much performance out of it but if aesthetics are more important than performance it'll do.
Assuming you mounted this on a mobile somewhere, you really should have (or borrow) a VHF/UHF SWR meter and trim or adjust the antenna during initial installation. Without pressing your hot-button, I still have to agree with the others that you should know this stuff. Hams are supposed to know what they're doing and knowing how to tune an antenna is one of the most basic skills you need to have in your bag of tricks.
Assuming you mounted this on a mobile somewhere, you really should have (or borrow) a VHF/UHF SWR meter and trim or adjust the antenna during initial installation. Without pressing your hot-button, I still have to agree with the others that you should know this stuff. Hams are supposed to know what they're doing and knowing how to tune an antenna is one of the most basic skills you need to have in your bag of tricks.
+1
How the %^&( did someone get their ticket without even understanding antenna tuning?
Are the tests that dumbed down these days?
thank you, thank you very much. I guess since I do have a life and am a very busy person I dont have time to remember every single thing that I learned about ham radio. If I can remind you that people post questions on this site because they do not under stand things, and they are looking for help...NOT to have some know-it-all be a jerk. Thanks.
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I did get my answer but in the future I will remember not to post any questions on here that could at all be considered a "dumb" question. And no, I did not memorize all the questions. I read the book and took the test like everyone else. But I mean really, I haven't tuned an antenna in years...people do forget. Some of you were helpful, and some of you were not. People don't get into this hobby to be treated like dirt, and know I finally understand why the retention rate can be so horrible with hams in some groups.
This comimg from someone that didn't know 10 meter voice is on USB between 28.3 and 28.5.MHz and not some other mode. You should've known that one.
reedeb
Member
+1
How the %^&( did someone get their ticket without even understanding antenna tuning?
Are the tests that dumbed down these days?
WOW!! Not a responce that I expected, NOR was warranted. Some of the things I learned when I took my test MANY years ago have long since slipped my mind. [I need to look it up from time to time to keep it in the old crainium]
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