VHF Contesting School — Antennas

       Experienced VHF/UHF hams will tell you that the antennas are easily the most important part of your station.  They are right.   Every single decibel is precious.   This is not like HF where you can throw up a random wire and often work DX.  From how high you get your antenna, to how much antenna you can afford to put up, right down to the feedline you use… it all adds up.   
    I am not an equipment expert, but I do know the advice about antennas is sound.   I designed my station around antennas first, and rigs second.    I’m not that crazy about telling guys which rigs and antennas to buy.   You should put some research into it yourself.     I used the “equipment reviews” at www.eham.net all the time when I was planning things back in 2002-2003.    They have many subcategories of ham gear under those equipment reviews, to help narrow your search for VHF this and VHF that.   

     Again, for maximum results on V/UHF, put the antennas first.    If you have homebrewer in you, or if your club wants a fun project, check out this link for the WA5VJB Cheap Yagis.    Multiple guys I trust say these give surprisingly good performance.  http://www.wa5vjb.com/yagi-pdf/cheapyagi.pdf   There are other links to WA5VJB Cheap Yagis, but I’ve been told that the one I just posted has the correct dimensions.    Use that pdf file as a reference.    I hope you enjoy V/UHF so much that you eventually step up to long-boom yagis with lots of gain.   But if you just can’t for some reason, get on with whatever you have and enjoy yourself.  

     EDIT — Jan 13, 2010.   I want to add the following link for quagi antenna projects.   This info comes from W9HQ out in EN43.   I quote, “These WA5VJB Cheap Yagis really are awesome.  The beauty of this design, as well as the N6NB quagi (see http://commfaculty.fullerton.edu/woverbeck/quagi.htm) is that there is no loss in the matching section.  Traditional matching approaches like gamma matches and such can get pretty lossy at VHF and especially UHF freqs.  But with these designs, the matching is built into the driven element, so you get all that back for free.”  
     W9HQ continues…”The ‘cheap yagis’ are literally a one to two hour project.   And you can build a whole stack of them for less than $20.   If you have one of the ‘wonder rigs’   (Such as Yaesu FT-857/897, Icom IC 706MkII, Kenwood TS-2000 — all HF bands + 6, 2 and/or 70cm)  then don’t let not having an antenna for VHF/UHF stand in your way of getting on the air.”    END OF EDIT. 

   Feedline is so much more important than it is on HF.   The db losses at higher frequencies become much greater.  There are better feedline experts than I, but if you have junk coax and you’re trying to work weak ones on VHF, you’re shooting yourself in the foot.    Sometimes just improving old or lossy coax can really make a big difference in what you hear and work.    To make these 200, 300 mile contacts, you want every last db you can get.   A few db may be the difference between no signal and good copy (with headphones) in the S1 range.   You don’t want to wimp out on coax.   Here are a few links that show the loss characteristics with various coaxes.   http://www.therfc.com/attenrat.htm   or try   http://www.ocarc.ca/coax.htm     I found these links by Googling “coaxial cable loss chart”.   Notice how large the losses are when you have a 100′ or more run of poor coax at 144 or 432 MHz.   Consider feedline to be part of your antenna budget and invest accordingly.   It will pay off.  

    On VHF/UHF get your antennas as high as you safely can.   Fellows have reported better results by getting an antenna just 10 or 15′ higher.   Try to get antennas out of the way of obstructions.   This is especially important as you move higher in frequency.    If you can do it, step up to a 7, 9, 11 element beam, instead of a shorter one.   Remember it’s all about more decibels.   The longer the boom, the higher the gain.             
    For best results in a contest, as well as general weak-signal VHF hamming, you want horizontally polarized antennas.    80-90% of V/UHF contesting activity is on SSB/CW, using horizontal antennas.      What I do in trying to promote FM contesting to Joe Q. Ham is considered unorthodox by some.    The FM angle works best in metropolitan areas where there are many hams nearby.    If you know there are plenty of hams in your area who do FM contesting, or enjoy FM simplex, then try to have some vertical antennas.       Just know that if you want to work the majority of stations in a contest, you’re going to need flat side antennas and an all-mode rig at some point.  

   Making a horizontal loop for a given band is a cost-effective way to hear farther on SSB.   It’s not as good as a yagi, because loops are omnidirectional.   But you don’t have to rotate them, and sometimes you hear things with a loop that you wouldn’t with a beam pointed in the wrong direction.   It’s all about having options.    
    A fellow recently sent me this link for an interesting-looking horizontal loop system on 2m SSB.   I like the fact that these loops were stacked, since you get an extra 2-3db of gain for stacking 2 loops, and 5-6db gain for stacking 4.   I’m not saying how well these loops will work, but visit http://home.comcast.net/~ross_anderson/HOCollinear.htm   If someone tries these, let us know how they work.   Also make sure you go to the bottom of that webpage because there are many other links for antenna ideas.    I’m sorry to say I am not the guy to discuss homebrewing with.   I’m all thumbs that way.    Consider me only the messenger. 

    Since this is for beginners, I will wrap things up here.  The antenna projects will get you thinking.  
    If you’re new to VHF and wondering how well your station gets out, a contest is the single best time to gauge what you can do.   The sheer number of stations on the air presents a great learning opportunity.

3 Responses to “VHF Contesting School — Antennas”

  1. Steve Turner Says:

    Have you ever stacked cheap yagis? I am building a pair of 6 elements for stacking side-by-side in vertical polarization and trying to confirm the relationship between the driven elements. If you’re interested I’ll let you know how it works.

    Steve

  2. kc9bqa Says:

    Hi Steve,

    Todd KC9BQA here. I have never done anything with cheap yagis. I’m just the messenger. Does anyone else have experience they can share here?

  3. KA2BPP Says:

    Steve,

    you probably alraedy got an answer but the driven elements need to be in the same plane, that is both loops at bottom or both on top. Horizontal would be either both to the left or right.

    Hope that helps
    Artie
    KA2BPP