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 0000Z…Ding! 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.