G5RV vs. Ground Plane on 80M: G5RV by 5dB!

Excited by the pos­si­bil­ity of adding to my DX worked totals on 80M dur­ing the ARRL DX CW con­test a few week-​ends ago, I hur­riedly installed a new 80M ground plane (GP) antenna. Like the year before, I intended a single-​band effort and the new GP was going to be my secret weapon.

I used my 50′ (15 meters) tall fiber­glass mast and ran a 14 gauge wire ver­ti­cal ele­ment of 44 feet. I also fab­ri­cated three 44′ long radi­als and fas­tened them in the yard at approx­i­mately 5′ high. I cre­ated a cur­rent balun by coil­ing side-​by-​side about 8 turns of RJ-​213 coax­ial cable lead­ing to my remote coax­ial switch. Tun­ing was to be accom­plished by a LDG tuner in the Schack.

It took about an hour and a half to get every­thing placed and hooked up. I was done just before sun­set, and I knew there would be some nice gray line enhance­ment for my test­ing. I turned the antenna selec­tor switch to the cor­rect posi­tion, found a clear spot around 3510 and pressed the tune but­ton. The SWR came down to unity in a few seconds…beautiful! Tun­ing around the bands I did not yet hear any EU sta­tions but DANG the whole band sounded extremely quiet! My antic­i­pa­tion grew await­ing the inve­vitable erup­tion of con­test sig­nals on a band as smooth as glass!

On a whim I dropped over to “Crappy”, my affec­tion­ately named G5RV. By the way, here is the EZNEC+ pro­file for Crappy. The feed point is at approx­i­mately 9 meters, or a bit less than 30 feet. Note the Y-​axis is point­ing Due North.

See what I mean? The antenna fits the name! Any­ways, there was a bunch of noise on the G5RV that just wasn’t on the GP. I told myself not to be scared, this was all high-​angle stuff and should be expected. That said, I did expect elec­tri­cal noise to be much higher on the ver­ti­cal (save this thought for later.)

Switched back the ver­ti­cal in time for the start­ing bell at 0000ZDing! Yup, a bunch of sig­nals erupted just like I knew they would. Took a few min­utes to sweep up the band, copy­ing calls call­ing into N1MM log­ger and stor­ing them on the bandmap for pounc­ing on in a few min­utes. Hear­ing the old faith­fuls: OM7M, F2DX, Plenty of strong Ger­man stations…Nice!

Back to OM7M, hit F4 to send my call. Nope, didn’t come back to me. OK, no problem…it’s not even dark here. Next one…same thing. Next…huh? These guys are all con­test super-​stations run­ning KWs and big anten­nas. They keep call­ing CQ so it is not as if I have com­pe­ti­tion at the moment. I make a sta­tion sweep: SWR is fine, trans­mit­ting at 100W. All seems good. I switch back to my old G5RV to tune up. SWR also fine, band is nois­ier, and received sig­nals are still strong. It is now 0042z. I hit F4 to call OM7M again.

We exchange and I log.

I turned back to the GP and click on F2DX in my band-​map. No calls returned. Switch back to my G5RV and call. I log F2DX at 0048z. DL9FBL a minute after that.

Great,” I tell myself “This new antenna sucks.”

I let the fail­ure wash over me for a few min­utes, then switch back to the G5RV for good, and to bet­ter than expected results over­all. I Actu­ally try the GP through­out the con­test just hop­ing it was prop­a­ga­tion anom­alies. It wasn’t propagation.

Mod­el­ing ex post facto reveals some­thing a bit counter-​intuitive about the anten­nas, but some­thing I had seen expressed in the Low-​Band DXing and ARRL Antenna books before: Low horizontally-​polarized wires will often have bet­ter gain at low take-​off angles than ver­ti­cals espe­cially over ground with aver­age or lower con­duc­tiv­ity. I mod­eled both anten­nas as accu­rately as pos­si­ble and over­laid the pat­terns toward EU to val­i­date if I were con­fronting this sit­u­a­tion as well.

The GP looks pretty much like it does in the text­books, except for the a slight reduc­tion in gain toward the West. I could only accom­mo­date radi­als in the North, East, and South­east direc­tions. Over­all gain seemed to be pretty much as pre­dicted as well. Not a high-​gain antenna, but get a load of that clas­sic low-​angle pattern!

Then I placed the ele­va­tion slice trace from my G5RV model:

The outer ring scale being the same for each antenna, you can see the low G5RV is stronger by 3-​4dB at 30 degrees. HFTA mod­el­ling indi­cates sig­nals arriv­ing from 28 degrees the major­ity of times. Less often sig­nals arrive at lower angles (17, 12, and 4 degrees).

Here is the Azimuth slice at 30 degrees:

This pat­tern also reveals even bet­ter gain toward Africa and into the Pacific. And yes, I had no prob­lem work­ing KH6s dur­ing the con­test (or any time), and around this time of year South Africa comes boom­ing in (although not in the con­test this year.) Morocco and Canary Islands are ear-​splitting in con­tests on 80M…I can guar­an­tee these multipliers.

I would say the over­lay val­i­dates both the text­book knowl­edge and my own recent expe­ri­ence. My sig­nal is just enough above the noise to work suc­cess­fully into EU dur­ing con­tests on the G5RV. I was not being heard on the Ground Plane. If I were run­ning 500 watts or greater I bet I would be heard on the Ground Plane.

There was not much dif­fer­ence between the G5RV and the GP on receive for large sta­tions except into the Caribbean, where the GP had a slight edge. High-​angle sig­nals – state-​side – were being atten­u­ated by the GP pat­tern and thus made the Caribbean sta­tions pop in com­par­i­son to the G5RV. That said, G5RV was bet­ter over­all. For smaller sta­tions from EU, the G5RV was a bet­ter RX and TX antenna.

The GP is not a bad antenna. Heck, I even worked YN2DD after the con­test on 60M using the GP (a con­so­la­tion prize…I don’t want to think how the G5RV would have been bet­ter. Must. Not. THINK) My ground con­di­tions in Mid­dle Ten­nessee are con­sid­ered aver­age at best. The com­par­i­son would be much dif­fer­ent if I lived on the beach sur­rounded by salt-​water where I am sure a ver­ti­cal antenna would be the best antenna ever. I don’t have salt water any­where near me so I need to work with what I got. Speak­ing of salt, I also take the mod­els with a grain of it. I try to be con­ser­v­a­tive in my approach. My ground char­ac­ter­is­tics in EZNEC are prob­a­bly worse than actual so that I don’t get inflated gain. I don’t get too worked up over a mod­eled dB here or there.

Remem­ber my ini­tial reac­tion to how quiet the GP was? I have a notion how ver­ti­cal anten­nas are elec­tri­cally noisy, and maybe true in the­ory. The lack of gain at high-​angles has the effect of low­er­ing close-​in sig­nals and sta­tic on 80M in this real-​world exer­cise. This con­di­tion has inspired me toward think­ing about a receive-​only four-​square for low-​bands. I am sure it would play very well even on my small city lot. I would not have believed it unless I heard the noise reduc­tion with my own ears.

Who would have believed that a low, non-​resonant, much-​maligned and poorly con­structed antenna such as my bent G5RV, that goes by the name of Crappy, would be a supe­rior antenna to a clas­si­cally con­structed ground-​plane antenna on 80M.

Sober­ing.

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