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Anything to do with wire antennas, including how to build one, how different wire antennas perform, how to tune them or when to use a balun, and what types of wire work best in certain antennas.

5
votes
5answers
93 views

Signal path to maximize RFI rejection in an urban environment

Urban ham here (Cambridge, MA - FN42ki - KC1JZE) looking for tips to make this hobby possible in the city. I rarely can hear both sides of HF phone transmissions, and have yet to make contacts despite ...
3
votes
5answers
113 views

Tune a very short 3-5m random wire for 40m (around 7.030 MHz) for listening or occasional QRP CW sending

I would like to use a small trx first for listening CW on 7030 kHz and then for transmitting, locally, among friends. My conditions are "prohibitive" as for antennas: a block of flats, 4th floor in ...
4
votes
2answers
105 views

Antenna suggestions for 160m band in smallish yard?

I have a decent-sized but not huge yard (roughly 50x100' / 15x30m) and I'd like to get on the 160-metre band. It's hard enough to get out on this band so I'm looking to do something reasonably ...
3
votes
2answers
232 views

HF SWL antenna wire? Will plain 16-Gauge copper wire work well enough?

Planning to set up a HF antenna for RX-only. However, I can't decide what kind of wire to use. I want to buy something new. My first thought is to buy a spool of 16 Gauge copper wire, but am hoping ...
4
votes
3answers
197 views

Can an antenna be too powerful for certain receivers?

I'm brand new to shortwave radio and have been researching what kind of a receiver to get. I'll use it on the antenna I'll build (longwire, 50-100 feet) for shortwave listening; no transmitting. Right ...
1
vote
3answers
338 views

If i connect two antennas to one radio using a t connector will it work?

If I connect two antennas to one radio using a t connector will it work? If a connect 2 antennas (a mag mount + a dipole?) to the same radio with an adapter will it work normally on 2M band and will ...
1
vote
2answers
138 views

Impedance effect of using 75 ohm coax between transmitter and an EFHW antenna

I have been given several hundred feet of very high quality 75 ohm coax. I need a run of about 36' from my QRP transmitter (FT-817 with elecraft T1 tuner) to an EFHW antenna (about 75' long). Running ...
1
vote
4answers
394 views

Long Wire Antenna for SWL

Please don't laugh. I am totally ignorant about amateur radio. When I tried to use the internet to answer questions, all I have found are formulas and charts I don't understand. For example; I ...
2
votes
2answers
145 views

Simple antenna for an old Grundig Satellit 800

I just got my technician license, and I'm just fooling around a bit on the Grundig. I'm trying to pull in WWV from NJ, so 1st, is that possible with the radio whip? I've tried the built-in whip on 5,...
5
votes
1answer
117 views

HF/VHF antenna for high altitude balloon

I'm working on the design of a dual band transmitter for use on a high altitude balloon. I'll be transmitting on 2 meters and 20 meters (APRS and WSPR) with about 50 mW. To keep the weight to an ...
1
vote
2answers
209 views

Suggestions for above-roof mounting Windom

Setup We just finished an addition on our house, and I have (on the diagonal) ~65 feet of space to work with. The pitch of the roof raises ~5-6 feet from the gutters to the apex of the roof. Roof ...
4
votes
1answer
392 views

Is ladder line necessary when using a non-resonant dipole through a tuner?

I've heard if I have a dipole of some arbitrary length, or a random wire, the SWR can be very bad. An antenna tuner can present a decent match to the transmitter, but the SWR on the feedline will be ...
0
votes
2answers
289 views

G5RV Jr and Ladder Line feed Lying Flat on the Roof?f

a semi-old, mildly grumpy, damn lazy new General Class Op, back after nearly 40 years since last license. Live in an old 2 story Mediterranean Sunset District Avenues home with a flat, beam-bitumen-...
5
votes
3answers
287 views

HF antenna design for high-altitude balloon

I'd like to put a WSPR or JT65-like transmitter on a high-altitude balloon, but lacking much experience with HF antennas, I don't quite know where to start. I'm thinking it will operate on 20 meters, ...
2
votes
1answer
107 views

75Ω Wire FM antenna

I was recently given an older, but really nice broadcast FM receiver (88-108Mhz) by neighbor, but I am confused by the antenna connector and labeling. for the FM antenna connection, there are two ...
1
vote
1answer
140 views

Wide bandwidth HF power combiner schematic and formula

I want to build (not purchase) a wide bandwidth power combiner. It should combine signals from 2 TFD antennas cut for 15 MHz lower frequency and used for receive only. Upper frequency is 30 MHz so ...
7
votes
1answer
151 views

Tuning a wire antenna by folding

Last weekend we tuned a quad loop for 80 m and 40 m. Instead of cropping, we folded the isolated wire using cable ties as shown in the picture below. After folding several quite large sections of the ...
3
votes
1answer
423 views

How to probe a dipole antenna?

I want to start experimenting and tinkering with antennas, starting with ½ wave dipoles. I will be measuring the AC voltages on both the transmitter and the reciever antennas simultaneously. And by ...
1
vote
3answers
155 views

Is cheap Chinese coax wire ok to use as an antenna?

So I've been following this guide on how to build an antenna for a High altitude balloon: link In the guide they say to use RG174 wire, which is why I bough some cheap RG174 wire off Ebay. I guessed ...
4
votes
3answers
191 views

Suggestions for HF antenna for occasional use on my sailboat

I have had a license since I was a kid, but have not touched anything ham radio related in years. I have been thinking about diving back in and combining it with my sailing. I'm looking for thoughts ...
1
vote
1answer
90 views

Transition Point Between Fan and Cage Dipoles

A fan dipole is a dipole with multiple active elements, either for different frequencies or different directions (see turnstile antenna) while a cage dipole emulates a larger conductive by having ...
2
votes
2answers
376 views

Optimal antenna orientation for High altitude balloon?

(First of all, I hope this is the right subform, please correct me if I'm wrong) I am using a 433 Mhz LoRa Radio to communicate with a high altitude balloon and am using an antenna like in this guide ...
6
votes
2answers
802 views

What ways are there to extend an antenna?

I am using an arduino micro controller with a LoRa radio module to communicate. The shield has 2 ways of connecting an antenna: either a SMA jack or a hole for soldering. Now my problem is this: I ...
3
votes
1answer
155 views

Using an HF antenna for VHF scanning

Are there any disadvantages (or advantages) to using a long-wire HF antenna for wide-band VHF reception? Or would feedline losses make that useless compared to a ground level ducky or short whip? (...
5
votes
1answer
1k views

Could a weather balloon make a good antenna?

I can't afford a massive tower, but I can get a weather balloon much higher. What kind of set up and wire would work best to get the maximum efficiency and height?
6
votes
4answers
538 views

How would you get an “I'm alive” message to family in another state using amateur radio?

I'm researching options for getting an "I'm alive" message during a disaster response out to family in another state that aren't HAMs. There are likely to be a lot of possible answers that are art ...
1
vote
1answer
697 views

Do reflector and director widths (wire size) affect Quagi bandwidth?

A 2m Quad antenna made from 1/2" tubing will have a larger bandwidth than the same Quad built with 14 AWG wire. Would the respective bandwidths be maintained if both Quad loops were made into Quagis ...
6
votes
3answers
237 views

Wider wire = picks up more energy, yah?

I have seen many discussions re: wire gauge, insulation, velocity factor and K-factor...unfortunately, statements from various sources are not always in agreement, but that is not the issue. The issue ...
0
votes
1answer
187 views

RCA victor 35x tube radio loop antenna replica?

There is this one youtube video I have not been able to find again, where someone with a similar model radio was making replica of the original loop antenna on the back. I am wanting to make a ...
4
votes
2answers
376 views

Can I use old TV FM card as SDR?

I tried searching a lot before, but couldn't find anything about it; I have an old TV/FM card from an old computer, I wish to know if it can be used as an Software Defined Radio, and if yes, how? The ...
3
votes
3answers
274 views

Which is better in my situation: Balanced dipole, or as much wire as possible in the air?

I'm finally getting to the point of hopefully putting up a HF antenna. The idea is to start with a simple, straight wire dipole using trees as support points. (No traps or coils.) However, with the ...
2
votes
2answers
654 views

Recommended 9:1 unun core type(s)

I would like to construct a 9:1 unun that connects my QRP transceiver to a random-wire antenna. The transceiver's antenna connection is an unbalanced BNC jack and the random-wire antenna is, well, a ...
4
votes
3answers
1k views

Using inner conductor of a coax feedline as an antenna

Can I use the inside conductor of coax to radiate RF energy? My in-laws have some sort of attic antenna installed many years ago for broadcast reception, which I would love to temporarily co-opt for ...
0
votes
1answer
207 views

Testing my HB-1B QRP CW Transceiver on 40m

I'm a new ham and have only used 2m/70cm so far. I have recently completed a QRP CW setup: a YouKits HB-1B transceiver and a simple wire dipole. I haven't made any contacts yet, and I'm wodering if ...
2
votes
1answer
141 views

Would a covering like aluminised kapton effect antenna radiation pattern?

I'm looking at using a 1/4 wave whip antenna for a transmitter. If possible I'd like to cover the antenna in very thin (0.02 mm) aluminised kapton for reasons unrelated to the radio system; to be ...
1
vote
2answers
1k views

What kind of wire is best to use for connecting a FM radio to the antenna?

What kind of wire is best to use for connecting a FM radio to the antenna? This article doesn't say what kind of wire is used.
2
votes
1answer
135 views

How do I simulate a receiving antenna in EZNEC simulation tool?

I have a situation where I need to find receiving antenna impedance when it’s $\lambda/2$ distance from the transmitting antenna. Both are dipole antennas. Is it possible with EZNEC?
1
vote
3answers
2k views

How to produce a NEC antenna file (and what software to use it with)?

So I'm really trying to get to grips with antenna radiation patterns, and more importantly things that are to close to the antenna that might interfere. I've downloaded Qantenna and 4NEC2 to try and ...
5
votes
1answer
453 views

Minimum thickness of whip antenna

I'm looking at designing a communication system using very low power transmitter (0.1 W) and operating in the 400 Mhz range. For my uses I think a quarter wave whip antenna would work well, so I've ...
4
votes
1answer
189 views

How far the near-field reactive region extends from the transmitting antenna?

I am doing research on near-field harvesting. In my situation the transmitting antenna is a dipole antenna operating at 2.45 GHz and its length is 14 cm long. I am trying to find how far near-field ...
6
votes
2answers
367 views

Simulating two antennas (transmitter and receiver) using 4nec2 tool

I am trying to find near field mutual coupling affects between two antennas - one being transmitter and other being receiver. The receing antenna is fed with very little voltage (I think, if I don't ...
1
vote
0answers
175 views

What will be antenna impedance of a dipole antenna when it is kept lambda/2 away from the transmitter

I understand that half-wave dipole antenna, which is in far-field, impedance is around 73 ohms. If I keep same antenna in near-fied at distnace lambda/2 from the 1.25 lambda length tranmiter?
3
votes
1answer
541 views

maximum distance omnidirectional antenna

I want to know this omnidirectional antenna's maximum distance: gain 15 dBi frequency 2400 GHz power 50 watts
2
votes
1answer
114 views

Dual Band Antenna Matching

I am building a wideband dual band omni for school. My antenna is about 2m long. The antenna length basically has two sections (divided by ports) - from 0 - 1.8m (This length is for 20-180MHz) and ...
3
votes
2answers
749 views

Dipole versus ungrounded end fed for HF RX

I've built a 2 meter ground plane antenna that works pretty well for RX and has a decent SWR on 2 meters with my Alinco. However, I'm experimenting with SDR quite a bit and would really like to build ...
3
votes
1answer
154 views

Rhombic Polarization Question, provided radiation maps

I am trying to engineer my first antenna to get on the air. I need to hit a repeater 50 miles away at a lower elevation than me so that I can use its IRLP nodes. Would this mean I am looking for low ...
3
votes
2answers
2k views

Most effective placement of receive-only long wire antenna?

I've currently got a long-wire antenna (made from 24 ga. wire recovered from CAT-5) running to a receive only MW/HF radio. It is hung from a tree bough down to a window and looks approximately like ...
5
votes
2answers
163 views

Theoretical Wifi antenna not working for the expected range

You buy a "20dBi omni" Wifi antenna, operating in the 2.4-2.5GHz band. You note that the expected range is not achieved from this 300mm long antenna. What could be wrong? Can someone please tell me ...
4
votes
2answers
3k views

What is the impedance of a 1.25 λ dipole antenna?

I would like to make a dipole antenna. This particular antenna is used for reception only; no transmission is involved. I would like to receive as much power as possible by this antenna as it is used ...
3
votes
2answers
367 views

70cm antenna for an apartment

I have a blind friend who can't put anything outside, and is restricted to antennas near the window in his apartment. Luckily he lives closer to the top, which helps with range a little bit. He has a ...