musen de renrakusita.

It is pronounced むせん で れんらくした.

• 無線 = むせん
• で = で
• 連絡した = れんらくした

In normal writing, Japanese usually does not use spaces, so it would normally appear as:

無線で連絡した。

無線 literally means wireless or radio communication.

In this sentence, it usually means something like:

• by radio
• over the radio
• via wireless communication

The exact English wording depends on context. For example, it could refer to a radio set, walkie-talkie, or some other wireless system.

で is being used to show the means or method of doing something.

So:

• 無線で = by radio / using wireless communication

This is the same basic use of で as in sentences like:

• 電話で話した = spoke by phone
• メールで送った = sent it by email
• バスで行った = went by bus

So here, で tells you how the contact was made.

連絡した is the past tense of 連絡する.

• 連絡する = to contact / to get in touch / to communicate
• 連絡した = contacted / got in touch / communicated

This is a very common pattern in Japanese:

• noun + する = a verb
• past tense becomes noun + した

So:

• 勉強する → 勉強した
• 電話する → 電話した
• 連絡する → 連絡した

Japanese often leaves out the subject when it is understood from context.

So 無線で連絡した。 could mean:

• I contacted them by radio.
• He contacted us by radio.
• We got in touch by radio.

The sentence itself does not tell you who did it. You figure that out from the situation or previous sentences.

This is very normal in Japanese.

Japanese also often omits the object if it is already clear from context.

So 無線で連絡した。 does not explicitly say:

• contacted whom
• contacted about what

It just says that contact was made by radio.

If you wanted to include the target, you could say things like:

• 本部に無線で連絡した。 = I contacted headquarters by radio.
• 彼に無線で連絡した。 = I contacted him by radio.

無線で連絡した。 is in a plain, non-polite style.

That does not automatically mean rude. It just means it is not using the polite -ます form.

Compare:

• 無線で連絡した。 = plain past
• 無線で連絡しました。 = polite past

The plain form is common in:

• narration
• diary-style writing
• casual conversation
• reports depending on style

Yes. 無線で連絡をした is also correct.

Compare:

• 無線で連絡した
• 無線で連絡をした

Both mean basically the same thing. The version without を is very common and natural in everyday Japanese, especially with する nouns like 連絡.

Sometimes using を can sound a little more explicit or slightly more formal, but in many cases the difference is small.

Yes. 連絡する is a broad word.

Depending on context, it can mean:

• contact
• get in touch
• inform
• communicate

So 無線で連絡した could mean:

• contacted someone by radio
• communicated by radio
• sent word by radio

The exact English choice depends on the situation.

Usually, で is the natural choice here because it marks the means/method.

So:

• 無線で連絡した = natural

Using another particle would usually change the meaning or sound wrong in this context.

For example:

• 無線に連絡した would sound odd if 無線 means radio/wireless communication
• に is used for the target of contact, as in 本部に連絡した = contacted headquarters

So the structure is:

• [method] で
• [target] に
• 連絡した

Example:

• 本部に無線で連絡した。 = contacted headquarters by radio

It is a real and useful word, but the nuance depends on context.

無線 often sounds connected to:

• radio communication
• professional equipment
• police/fire/rescue communication
• ships, aircraft, military, field operations
• walkie-talkies

In everyday modern life, if you mean things like Wi-Fi or mobile communication, people may use more specific words instead, such as:

• Wi-Fi
• 携帯
• スマホ
• 電話

So 無線で連絡した sounds natural in the right context, especially where radio communication is involved.

The spaces are probably only there to help learners see the parts:

• 無線
• で
• 連絡した

In normal Japanese writing, you would usually write:

無線で連絡した。

Japanese does not normally separate words with spaces the way English does.