HF in Big City

Discussion in 'Antennas, Feedlines, Towers & Rotors' started by UB3ARM, Jan 7, 2019.

ad: L-HROutlet
ad: l-rl
ad: L-MFJ
ad: K5AB-Elect-1
ad: MessiPaoloni-1
ad: Subscribe
ad: Left-3
ad: Left-2
  1. UB3ARM

    UB3ARM Ham Member QRZ Page

    Hi Dear Friends,

    I think that my question is addressed at HAM`s from a big city such as NY, LA, Berlin, Paris and so on, and for who are living in an apartment, what kind of HF Antenn are you use?
    Thank you!
     
  2. KE0EYJ

    KE0EYJ XML Subscriber QRZ Page

    I'm just plain lucky, here at HL1ZIX, in downtown Seoul -- city of 12 million+.

    I have a homebrew 20m yagi, and a doublet between 50 and 70 feet high on the flat roof. The best combo I used to have was a 20m Moxon monobander (which also worked well on 17m) and a doublet. The current doublet needs to have its orientation changed. I took the Moxon down, only because we had some typhoons come through. I really do miss it, although the 20m yagi works on 20 fairly well (it's got a shorter boom).

    We've been through this same question with a ham in New York, who was able to put one antenna on the roof. He decided on a cobweb antenna, after much discussion and advice from others. You might consider the same, if you have roof access, and can put up one multibanded antenna.

    In my extensive experience in Seoul, three types of antennas work: horizontally-polarized dipoles, loop antennas (although they cause RFI issues with neighbors, at more than QRP levels), and antennas with tight bandwidths that naturally filter noise. A screwdriver vertical can work surprisingly well in the city, due to the tight bandwidth from required tuning. My friend HL5ZEE has a Hi-Q vertical hanging off of the side of his apartment at 100 feet high. I tell him it's really a vertical dipole, in a way, because it's grounded to one steel pipe heading downward, rather than having radials. In any case, it sure works well for him. The Hi-Q has a tight bandwidth, and filters noise because of it. His also has the cap hat, so he saves some efficiency that way.

    What is your situation? Can you hang something out the window? Have roof access? How high is your place?
     
  3. KS2G

    KS2G Subscriber QRZ Page

    Need more information about YOUR apartment:

    What kind of building are you in?
    High rise?
    What floor are you on?
    Do you have access to the roof?
    Do you have a balcony?
    If so, how big is it?
    Are you allowed to put up something "permanent" -- or something that has to be taken down after each use?

    Tell us more.
     
    NH7RO likes this.
  4. UB3ARM

    UB3ARM Ham Member QRZ Page

    Hi Dear Team,
    thank you for your replies, unfortuntley i do not have access on the roof:(
    yes, I have a not big a balcony, 11 floor (37 m, near 121 feet)
    my building from ferroconcrete, in Moscow we have a problem with an access on the roof, but if I will have a not big construction near the window or balcony - will not have a problem
     
  5. KK4NSF

    KK4NSF Ham Member QRZ Page

    I've visited with a lot of hams in big cities with similar situations. With the Ferro-Concrete walls, an inside antenna is not going to work well. The folks I know who live in heavily urban areas (especially in Tokyo) tend to use either:
    A- a magnetic loop sitting out on your porch. You can either make one yourself, or buy one of the commercial versions.
    B- a very thin wire draped out the window, with a tuner.
    C- a base loaded vertical, like the MFJ Apartment Antenna upload_2019-1-7_19-52-15.jpeg

    Either of these will get your signals out... but it will be blocked by the building in one direction.

    The other option is to operate with a portable set-up from a park or similar open space.
     
    UB3ARM likes this.
  6. WB2WIK

    WB2WIK Platinum Subscriber Platinum Subscriber QRZ Page

    Ironically, New York City hasn't any real antenna restrictions, so any restrictions are HOA-based or "apartment owner" based. I've known hams in NYC who had towers and big beams spinning over the roofs of their apartments.
     
  7. KC8VWM

    KC8VWM Ham Member QRZ Page

    In Toronto on the 37th floor of a high rise building, I had a long fishing pole with a wire attached to it that I stuck out away from the balcony. Some of the wire just hung straight down off the end of the pole. A small lead fishing weight was attached to the end of the wire to help keep it hanging straight. The balcony railing metal was used as a counterpoise / ground and I usually only did this after it got dark outside to prevent neighbors in the building from detecting it.

    I remember the elevators in the building caused RFI noise and you could always hear static levels rise whenever they were in use. However, most people settled in after 9 pm or so and elevator activity subsided.

    If I was there today I would probably attempt a Cobweb antenna.
     
    Last edited: Jan 8, 2019
  8. KE0EYJ

    KE0EYJ XML Subscriber QRZ Page

    If you can make a good RF ground for it, a screwdriver antenna up that high can work really well. Basic full-bandwidth 1/4 wave verticals are far too noisy, but interstingly, something less efficient or with a tight bandwidth does OK on RX.

    As mentioned, my friend HL5ZEE has had great luck with his, up about 13 floors in Korea. He has to tune it with a kind of internal tuner box, for the band, so the bandwidth is tight and naturally filters noise. Hi-Q 5/160 (Military) Off My Balcony @ 35M.

    There are cheaper screwdrivers, and he also runs a far cheaper/simpler Superantenna vertical out the other side of the building. Not sure how that performs, by comparison, but you might ask him.

    I'm kind of amazed he can get away with it and not freak-out the neighbors. Most in Seoul probably couldn't, but he's a few hundred miles South of me in a more rural town.

    [​IMG]




    On another note, here's a 40m vertical dipole I made, which is about 10m long (half-sized, with coils). It loses some efficiency, but it sure did hear better than my full-sized 40m horizontal dipole -- only because the very tight bandwidth kept the city noise down. I want to say I only have about 10kc to work with, but I found that if I pull the bottom leg in or out, I can tune up and down the band. I got Chile and Australia on that thing, at 90w (but I was also 120 feet up).

    A 40m like this, on a 12m fiberglass Spiderbeam HD pole, wouldn't be practical for your application. You could, however, build a 20m with coils and cut it down to 5 or 6m in length. Could probably work a few other bands at a bit of loss, also.

    [​IMG]
     
    Last edited: Jan 8, 2019
    UB3ARM and KC8VWM like this.
  9. CX3CP

    CX3CP Ham Member QRZ Page

    Hi Alexey, As an example, Here in Uruguay the radio amateurs are Privileged as a National Interest by Law, that means we have no legal impediments to install our antennas, and specifically in case of buildings no co-owner and/or neighbor can oppose to the installation of the necessary antenna systems, unless there are some structural impediment at the roof or there is no useful space to install new antennas.
    Maybe the first thing is to investigate what are the rights and obligations of radio amateurs in your country.

    Who knows, good news could coming by looking at the law and statutes.

    regards, ;)

    P.D. many Country's also have the same Law enforcement for Amateur Radio Development, Uruguay is not the exception
     
    UB3ARM and NH7RO like this.
  10. K4MJA

    K4MJA XML Subscriber QRZ Page

    Привет Алексей,

    я живу в квартире, дом правда небольшой, квартира на двух уровнях и есть доступ к чердаку. Шуму наверное меньше чем у вас -- лифтов нет, да и американская одно-двухэтажная застройка не сравнится по плотности с московской многоэтажкой. В остальном похожие проблемы...есть диполи на чердаке и снаружи, вдоль края крыши, все не совсем резонансные, так как места мало и сложены в странные фигуры, да и крыша близко, но с антенным тюнером не проблема, работают, покрывают 15-40м. Тот что вдоль крыши даже на 80 метров как-то работает. Самые лучшие мои антенны это (1) MFJ-1775 и (2) HyGain AV 12AVQ. И ту и другую в принципе можно попытаться воспроизвести, и та и другая на ваш балкон возможно поместятся. Я их на стеклопластиковом телескопическом шесте поднимаю, когда надо. Постоянно их установить не получается, не дают. Всё это описано у меня в блоге на английском, вопросы есть- спрашивайте.

    Удачи!
    PS Если в доме есть знакомые, выше или ниже, а лучше и выше и наже, то можно попробовать натянуть проволоку с балкона на балкон, главное чтобы мимо окон.
     

Share This Page