WX Band Antenna

[JoshAR]

Hello all,

I've been thinking about getting or possibly building an antenna for receiving stations on the 162 MHz weather band. I just had a couple questions I was hoping to get answered.

I assume a vertically polarized antenna would be better due to the 20 dB loss from polarization mismatch? However, if that's the case, I've heard vertically polarized antennas aren't nearly as directional as those that are horizontally polarized. What would be the best in terms of directionality while not missing signals because of polarization mismatch?

I've also been looking around to see what's available to buy but haven't been able to find anything for 162 MHz. If I need to make my own antenna, what would be involved? I'm pretty much a total newbie when it comes to antenna design. Any help would be greatly appreciated.

[alok]

I got the Discone way back in 2004, it worked great, even used it on 6 meters to transmitt with just 8 watts SSB. Comet ( I think Comet still makes it ) makes one & MFJ too, the Comet cost more. I had the Comet. The Comet I had received 25-1300 Mhz and transmits 6 / 2 meters and 220 / 440. MFJ does the same.
I no longer have it because when I moved I did not take it with me, by then it was14 years old and still wotked great.
Al

[Mike-CT]

I've used VHF TV antennas and they work fine. I get 162mhz weather stations out to 70 miles 24/7. You could also cut a vertical dipole for 162mhz and put that outside for omnidirectional use.

[JoshAR]

Thanks for the ideas, guys. If I get something for NWR, I'll probably go with something directional.

I've also been considering the four element AIS antenna from Innovantennas. It's a bit pricey, but I'm very happy with the FM antenna I got from them.

[Russ-PA]

Directionality is less a function of polarization than of the type of antenna. A yagi can be mounted either for vertical or horizontal polarization, and in both cases it will be directional. A vertical will generally not be directional although it is vertically polarized. I've used a small vertical and also my 9-el FM yagi and neither gives me the signal reception quality that my ham HT with weather band using a small antenna attached does.

[JoshAR]

So if I'm understanding correctly, I should get good results with a vertically polarized yagi cut for the WX band?

I'm seriously considering the four element AIS antenna from Innovantennas, which can be found at https://www.innovantennas.com/en/sho...as%20shop.html. I'd love to hear any opinions you guys have, and if you know of anything that has the same or more gain for a cheaper price, feel free to send it my way.

[w9wi]

So if I'm understanding correctly, I should get good results with a vertically polarized yagi cut for the WX band?

I'm seriously considering the four element AIS antenna from Innovantennas, which can be found at https://www.innovantennas.com/en/sho...as%20shop.html. I'd love to hear any opinions you guys have, and if you know of anything that has the same or more gain for a cheaper price, feel free to send it my way.

What Russ said. Vertically-polarized Yagis are nearly universal for directional commercial fixed links on VHF, and also for FM-mode VHF ham radio.

My suspicion is a distrust of vertically-polarized Yagis comes from the difficulty of physically mounting such an antenna. You have to end-mount it to keep the mounting mast from interfering with the electrical performance -- which somewhat limits how large the antenna can be before it tends to sag out of alignment or start pointing at the ground
Alternatively, you mount it at the physical balance point -- and take the hit to gain & directivity...

The Innov you linked is an end-mounted antenna (from a very reputable company) and I think you'll be happy with it. It's expensive -- with Innov antennas you're mostly paying for mechanical robustness.

[JoshAR]

So, what kind of directionality am I looking at in your opinion? Being mechanically robust is great, but I also wonder how directional it would actually be with it only being four elements. The gain and F/B ratio on the website look pretty good, but I'm not sure how accurate those actually are. I have their 17 element FM yagi and it has served me very well for the last four years. Unless there's something better out there in terms of gain/directionality for the same or less money (keeping in mind that I don't have the tools or know-how to put together an antenna from scratch), the Innov is the one I'll probably get. I looked at Innov's 6 and 10 element AIS antennas as well, but the small increases in gain and F/B didn't seem worth the extra cost.

I'm planning to get a 20 dB preamp as well. I found one that's specifically for 162 MHz, so that should help with weak receptions.

[w9wi]

There are plots on that link -- I would treat them as a relative indication of directivity, something you can compare to plots posted by other manufacturers. In real life directivity is going to be subject to modification by your surroundings, your mounting arrangement, and other antennas nearby.

It's certainly not going to be as directional as your 17-element FM antenna. That said, there aren't as many NWS stations as FM stations and with any decent receiver, adjacent-channel interference is a non-issue. (what are you using for a receiver?) (how far are you from two-way radio operations, and for that matter, FM broadcast signals? Be careful with a preamp, overload, either of the amplifier or your receiver, is a potential issue.)

[NO2CW]

make it into a project and make your own antenna from measuring tape. otherwise, most ham radio 2 m antennas will give you decent results for reception. It all depends on your surroundings - a yagi worls only if out in the open with no reflections and obstructions. otherwise you may as well use a vertical or dipole. There is nothing "magical" built into the expensive commercial antennas. For example if you buy an AIS antenna it is likely to have weather related coating on the elements. electrically it is still the same antenna you can create with a tape measurer, dipole or vertically cut element.

[JoshAR]

Hi w9wi,

I'll be hooking it up to my Airspy. The preamp I'm looking at also has a filter to cut way down on FM signals as well, so hopefully that won't be an issue. This is the preamp I'm considering: https://v3.airspy.us/product/upu-fp162s/. There is a bit of insertion loss to deal with, but the amplification will hopefully more than make up for it. My nearest NWR station is 16 miles WSW of me, so in-band overloading hopefully won't be a problem.

I've also been talking to Justin, and he's willing to optimize the antenna for the NWR band for the same price, so I think I'm going to get it and we'll see what happens.

[JoshAR]

Thank you all for the help, it's much appreciated. I'm going to go ahead and purchase the antenna. I just have one more concern.

The more I've thought about it, the less sure I am that a preamp will be necessary with my setup. I only need a length of 50 feet of coax to go from the antenna to the Airspy, so a preamp may not be of much use. A lot of you guys know more about this than I do, so if you have a recommendation one way or the other, I'd be interested to hear it.

[w9wi]

It appears to be a decent preamp. I would ask whether there are other strong signals -- besides NWR stations -- within 15 miles or so. The NWR band is only 150KHz but there are other stations, both government & private, close enough in frequency to be of possible concern.

The specified gain of this preamp exceeds the specified insertion loss, so you're definitely ahead in that department. The ultimate practice would have the preamp installed at the antenna. (that's why the specs mention the ability to power this unit through a "bias tee") That allows the amp to make up for any noise that may be picked up by your coax. Of course, there are significant physical issues introduced - being exposed to moisture is not compatible with a long life

I will respectfully disagree with NO2CW's comment about a Yagi not being worthwhile if you can't have a completely-in-the-clear installation. Absolutely you want its surroundings to be as free of obstructions as possible. Unless it's entirely surrounded by conductive objects IMHO it will still well outperform a vertical or dipole. He is correct to suggest that spending more money doesn't buy much (or any) more electrical performance. The higher price of the Innov antennas buys you mostly mechanical robustness.

If it were me, my decision would hinge on how unhappy I'd be if I realized I'd wasted $53. Try the preamp but be ready to remove it if you end up with a bandful of spurious signals from overload.

[K4LY]

Josh,
I bought a 3 el weather band yagi on Ebay. I forget the seller, but do a search. It's mounted vertically on my tower, quite directional with a fairly narrow beam width and good front/rear. I can receive stations out beyond 100 miles with it 24/7 from my hilltop here in northwestern SC.

[JoshAR]

Hello everyone,

Just wanted to put out an update on the antenna situation. I got the antenna about a month ago and finally got it put up today. I have to say I'm impressed so far. I've been hearing Bloomfield, MO (141 miles) and Neosho, MO (123 miles) all day. There hasn't been much tropo on FM today either, so I'm thinking those should be baseline conditions, at least during the warmer months. Can't wait for the return of good tropo so I can really put this thing through its paces.

I decided to forego the preamp and I'm glad I did. With the Airspy's gain set near max, there were spots when turning the rotor where I got overload and I had to turn the gain down some.