Professional Antennas....Is it worth the expense? - Page 1
Forum section: electronics / rf-microwave

author: Radiosonde
author_rank: Contributor
timestamp: October 02, 2018, 03:11:58 pm
content: HelloAs I sayed I am a BIG Fan of Rohde & Schwarz Equipment....and its getting worse...a year ago I was only interested in SAs and Com. Test Setsbut probably two months ago I "discovered" the world of R&S receivers and antennas,a expensive world like it seemsSo...is it worth to invest about 300 bucks in a HK014 for example? Or would you prefer to buy a Diamond discone for 100?Whats about the shortwave antennas? Does someone uses some antennas from them?How they are performing? Is there a real difference to other brands?DIY isnt quite an option for me, I live in a really high place in the mountains with winds up to 160km/h and temperatures down to -25 degrees Celsius....also I dont have confidence in DIY antennas..every Time I see a small signal I think:How would this signal look with a professional antenna?Other Ham Radio brands aren"t an option too...everything or nothing...despite that the most of the normal Ham Radio antennas are not that cheap..cheaper than a R&S but without the R&S sticker on the bottom:)Regards

author: Wolfgang
author_rank: Super Contributor
timestamp: October 02, 2018, 05:01:38 pm
content: Hi,We have a little chalet in Ramsau, Styria about 1200m ASL. For similar reasons as you mentionend I bought a commercial antenna instead of making my own.Windspeeds can be way above 100km/h, and snow in winter is ample. So, I agree with you that going on the safe side is a good idea.In my case its a Diamond CP6S shortwave & 6m antenna ranging from 80meters to 60MHz. When you look at the construction, I would say that making all this yourself (including the radials)wont be a lot cheaper than buying one (a few hundred €). The CP6S has a max. wind speed of 180km/h (hope that never happens, I dont know what the rest of my house has).I used about 15m of H2010 cable from the antenna (mounted on the rooftop of a new (tin) roof) to the shack.Before hooking it up to the rig (Icom IC-7300), I measured it with an Anritsu MS2036A and found that the VSWR specs were OK. The only downside is the very narrow bandwidth at 80m,but the manual mentions this before and you can change radials if you dont like the 80m center frequency.If you can afford R&S gear the petty cash for the antenna wont be a problemRegards, 73Wolfgang DL1DWG

author: bson
author_rank: Unknown
timestamp: October 03, 2018, 01:26:03 am
content: For a load shortened antenna? No, I don't think it makes all that much difference; efficiency will be poor at 80/40m no matter what. Here's my Comet CHV-5X (a load shortened dipole) at 40m... as you can see the bandwidth is crazy narrow, and while a tuner can present a palatable load to the transmitter (BTW an IC-7300 also) the resulting radiation is still QRP territory. From a 100W transmitter! It actually works quite okay on 20m, where the the significantly increased bandwidth, impedance, and efficiency more than makes up for the slightly poorer propagation. BTW, the 40m band, with carefully trimmed radials (I measured 1mm to equal 25kHz of resonance shift) peaks in our Extra license portion of the band, so just a General license wouldn't even permit using it at peak efficiency! And shifting the resonance actually warps the impedance, so there's really only one good trim frequency.No matter how well made the antenna is, it just can't overcome the physical limitations resulting from shortening it. Mechanically I'm sure the R&S gear is excellent!

author: Wolfgang
author_rank: Super Contributor
timestamp: October 03, 2018, 01:42:05 am
content: Hi,the technical compromises stay the same with a given size limit, agreed. There is no such thing like "wonder antenna". At my location there is simply no better choice. 80m is problematic, but from 40m up I had quite some interesting QSOs with partnes a few 100km away, at least that. Trimming is difficult, to say the least, because the antenna basepoint sits more than 10m above ground and you would have to crawl up there and fiddle with radial lengths. As long as the VSWR is acceptable (and 40m and up it is OK) it wont bring a lot. I have a class A license, so I dont have your bandwitdh problem.The Diamond CP6S (4.6m length, 1.8m radials) is a bit larger than the CHV-5X, that probably explains why 40m is already working fine and bandwidths are tolerable.My dream antenna would be a 40m mast with some full size rotatable yagis from 80m up. No chance in my neighborhood.

author: bson
author_rank: Unknown
timestamp: October 03, 2018, 02:36:30 am
content: Oh yeah, same problem here! I too would love a giant 80/40/20m Yagi with a 1.5kW PEP PA behind it, blasting up to the legal limit as/when/if needed! It wouldn't go over well with the neighbors though, wouldn't fit on our lot (too big of a turn radius!), and I'd never get a building permit for it. I can also imagine the worst case scenario of it blowing over and dropping down onto people and parked cars on the street three stories below...Or the power lines on the way down!

author: Wolfgang
author_rank: Super Contributor
timestamp: October 03, 2018, 02:53:56 am
content: This exactly has happened to a radio amateur club in Bavaria. They had a 40m tower on top of a warehouse building with a flat roof (Grollmus furniture in Germering, Bavaria). One bad day a very strong wind broke off the hole tower, and only due good luck nobody was hurt by the debris. The insurance company paid for the damage, but refused to continue the contract. So - those were the days. The chance of getting at permit to re-erect the antenna tower at the same location is zero, after what happened.The would never get a permit to do that.

author: 9aplus
author_rank: Regular Contributor
timestamp: October 03, 2018, 07:59:33 am
content: Looking from island/shoreline experience:sea + winds => flying salt mistdry soil & stones => bad groundDuring the year often extreme wind and heavy rain...In summer, storms with lighting.Regarding HF, piece of right wire, plus proper 9:1 balun & "ground" => end feed halfwave.Can sustain extreme weather.On VHF or UHF in case that permanent service is necessary, than profi solutions may be better option.They are watertight and corrosion resistant...Yes, such antenna can be made in homebuilt environment with proper tools, machinery and raw materials... Can we still consider that "homebuilt"?Any way:20m of wire & ballun end feed 7MHz and up,50 MHz vertical loop,Air Band inverted V dipoleAll above homebuiltVHF AIS profi1090 ADS B profi / replaced with new antenna & cable after 4 years of permanent service,now whole summer within 50 top on FR24 global rank.73 9A4DB